Dual-Band, High-Performance Phototransistors from Hybrid Perovskite

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Dual-Band, High-Performance Phototransistors from Hybrid Perovskite and Organic Crystals Array for Secure Communication Application Xiuzhen Xu, Wei Deng, Xiujuan Zhang, Liming Huang, Wei Wang, Ruofei Jia, Di Wu, Xiaohong Zhang, Jiansheng Jie, and Shuit-Tong Lee ACS Nano, Just Accepted Manuscript • DOI: 10.1021/acsnano.9b01734 • Publication Date (Web): 08 May 2019 Downloaded from http://pubs.acs.org on May 8, 2019

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ACS Nano

Dual-Band, High-Performance Phototransistors from Hybrid Perovskite and Organic Crystals Array for Secure Communication Application

Xiuzhen Xu†,#, Wei Deng†,#, Xiujuan Zhang*,†, Liming Huang†, Wei Wang†, Ruofei Jia†, Di Wu‡, Xiaohong Zhang†, Jiansheng Jie*,† and Shuit-Tong Lee*,†

†Institute

of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory

for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu, P. R. China. ‡School

of Physics and Engineering, and Key Laboratory of Material Physics, Ministry

of Education, Zhengzhou University, Zhengzhou, Henan 450052, P. R. China.

1

ACS Paragon Plus Environment

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ABSTRACT: High-performance phototransistors made from organic semiconductor single crystals (OSSCs) have attracted much attention due to the high responsivity and solution-processing capability of OSSCs. However, OSSC-based phototransistors capable of dual-band spectral response remain a difficult challenge to achieve because organic semiconductors usually possess only narrow single band absorption. Here, we report the fabrication of high-performance, dual-band phototransistors from a hybrid structure of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) single crystal array coated with CH3NH3PbI3 nanoparticles (NPs) synthesized by a simple, one-step solution method. In contrast to C8-BTBT and CH3NH3PbI3 NPs with respective absorption in the ultraviolet (UV) and visible (Vis) region, their hybrid structure shows broad absorption covering the entire UV-Vis range. The hybrid-based phototransistors exhibit ultrahigh responsivity of >1.72 × 104 A/W in the 252-780 nm region, which represents the best performance for solution-processing, broadband photodetectors. Moreover, integrated phototransistor circuitries from the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array show application for high-security communication.

KEYWORDS: organic single crystal array, perovskite nanoparticles, organic fieldeffect transistors, broadband phototransistors, secure communication

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Dual-band phototransistors capable of simultaneous imaging in two spectral bands, e.g. visible (Vis) and visible light-blind bands, are attractive for a host of applications, such as communication, multicolor image sensing, and chemical and biological analysis.1-3 For instance, the security level in communications can be greatly upgraded by using the dual-band information provided by combining ultraviolet (UV) and Vis sensitive phototransistors.4 Recently, organic semiconductor single crystals (OSSCs) have been widely investigated as photoactive materials in phototransistors owing to the advantages of OSSCs such as strong light absorption, outstanding flexibility, and lowcost

manufacturing.5-8

High-performance

OSSC-based

phototransistors

with

responsivity exceeding 10000 A/W have been achieved through tailored molecular structures of organic semiconductors, improved crystallinity of OSSCs, and optimal device architecture.9-11 The sensitivity of OSSC-based phototransistors not only is much higher than that (~1 A/W) of commercial amorphous silicon-based phototransistors,12 but also surpasses that (~100 A/W) of single-crystalline siliconbased phototransistors.13 However, the OSSC-based phototransistors usually show narrow, single-band response in UV, Vis or near-infrared (NIR) light range,14 which severely restricts their applications as dual-band phototransistors. Organic-inorganic perovskite (CH3NH3PbX3, X = Cl, Br or I) materials possess excellent optical and electrical characteristics, including high optical absorption and quantum efficiencies, large carrier lifetimes, and long excition diffusion lengths, rendering them outstanding candidates as efficient light-harvesting materials.15-18 However, CH3NH3PbX3 usually show weak gate-modulated photocurrent at room 3


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temperature due to point defects at grain boundaries, polarization disorder of the CH3NH3+ cations, and thermal vibrations of the lead halide inorganic cages.19 Therefore, high-performance phototransistors are difficult to produce from CH3NH3PbX3 alone. In practice, CH3NH3PbX3 are usually combined with selected semiconductors, e.g. twodimensional (2D) materials like graphene and molybdenum disulfide, to form hybrid phototransistors.20-22 Given the high mobility and solution-processing capability of OSSCs, the hybrids of OSSCs and perovskites may offer opportunities to fabricate high-performance, broadband, and low-cost phototransistors. However, OSSCs are chemically fragile and easily damaged by the solvent of perovskite precursors. Further, it is difficult to produce perovskite/OSSC hybrid structures by directly coating the perovskite on OSSCs, such as in conventional perovskite/2D material hybrid devices. Herein, we present a simple, one-step dip-coating method for the production of a hybrid system of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) single crystal array coated by CH3NH3PbI3 nanoparticles (NPs). Importantly, the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array can be fabricated into dual-band and high-performance phototransistor with photoresponsivity of >1.72 × 104 A/W, which represents the best performance for phototransistors based on perovskites and OSSCs. Additionally, the devices show similar high photoresponsivity in the entire UV-Vis range and robust stability of >50 days in air. Exploiting these salient features, we integrate the hybrid phototransistors in a matrix array of 10 × 10 pixels and demonstrate its successful application in secure communication. Given their simple solutionprocessing capability, dual-band sensitivity and high performance, the perovskite 4


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NPs/C8-BTBT single-crystal array-based hybrid phototransistors should find applications in a variety of optoelectronic devices. RESULTS AND DISCUSSION A facile solution-processing method was developed for one-step growth of the hybrid structure of CH3NH3PbI3 NPs covering the surfaces of C8-BTBT single crystal array. C8-BTBT is a wide bandgap organic semiconductor with photoresponse in the UV range (Figure S1, Supporting Information). CH3NH3PbI3 NPs were fabricated via a solvent exchange method (details are described in the Methods). Scanning electron microscope (SEM) and transmission electron microscope (TEM) characterizations showed that the resulting CH3NH3PbI3 NPs were single crystalline with a diameter in the range of 110-210 nm (Figure S2, Supporting Information). The prepared CH3NH3PbI3 NPs (52.6 mg) were dispersed in a dichloromethane solution of C8-BTBT (4 mg/mL), forming a black suspension due to the strong absorption of perovskite in the Vis light range (Figure S3, Supporting Information). Note that the suspension remained stable with no noticeable precipitation after 60 min. The excellent dispersibility ensures the uniform distribution of perovskite NPs on C8-BTBT crystals during the following growth process. One-step fabrication of the hybrid structure was achieved

by

dipping

a

300

nm-thick

silicon

divinyltetramethyldisiloxane-bisbenzocyclobutene

(BCB)

wafer into

pre-coated the

with

suspension,

followed by withdrawing the wafer at a constant rate of 90 μm/s and annealing it at 60 oC

for 2.5 h. Figure 1a shows the polarized optical microscope (POM) images of the product 5


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on the BCB-covered silicon wafer. A large amount of discrete NPs of brown-yellow color could be observed on the surfaces of the ribbon-shaped crystal array. Comparing the morphologies of the product with pure C8-BTBT crystals (obtained from pure C8BTBT solution; Figure S4, Supporting Information), we conclude that the discrete NPs are CH3NH3PbI3, while the ribbon-shaped crystals are C8-BTBT. Further investigation by atomic force microscopy (AFM) and cross-sectional SEM demonstrate that perovskite NPs are formed on the surfaces of C8-BTBT crystals in an island structure, but not embedded inside the crystal (Figure 1b and Figure S5, Supporting Information). In addition, a clear boundary between the perovskite NP and the organic crystal is observed in the TEM image (Figure 1c and Figure S6, Supporting Information), indicating that the structure of the CH3NH3PbI3 NPs is not influenced by the deposition process, and the NPs form a physical contact with the organic crystal. Selective-area electron diffraction (SAED) patterns acquired from different regions in a C8-BTBT crystal and different C8-BTBT crystals on the same Cu grid, display identical diffraction patterns (Figure S7 and Figure S8, Supporting Information). This clearly verifies the single-crystalline nature of the crystal. To further investigate the structure of the hybrid perovskite NPs/C8-BTBT single crystal array, X-ray diffraction (XRD) characterizations of the hybrid composites, pure C8-BTBT single crystal array, and pure perovskite NPs were performed (Figure 1d, and Figure S9, Supporting Information). All XRD peaks of the hybrid composites can be assigned to C8-BTBT and CH3NH3PbI3 without un-identified diffraction peaks. It suggests that organic crystals and perovskite NPs are physically attached and no new phase is generated 6


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during this process. Note that the peak intensities of the perovskite are much lower than those of the C8-BTBT single crystals due to the relatively small quantity of perovskite in the hybrid composites. Figure 1e displays the absorption spectrum of the hybrid perovskite NPs/C8-BTBT single crystal array. In contrast to pure C8-BTBT single crystal array and CH3NH3PbI3 NPs, which respectively absorbs UV and Vis light (Figure S10, Supporting Information), the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array exhibits strong absorption in the entire region of 250-800 nm, and is thus suitable for the construction of broadband photodetector spanning from UV to Vis region. Phototransistors were fabricated from the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array with a top-contact geometry. 300 nm-thick BCB was used as a dielectric layer, whose capacitance was determined to be 2.3 nF cm-2 by the frequencycapacitance (C-f) measurement (Figure S11, Supporting Information). Au source (S) and drain (D) electrodes were thermally evaporated through a shadow mask. The channel length (L) and width (W) were 20 and 125 µm, respectively (Figure 2a and Figure S12, Supporting Information). Figure 2b and Figure S13, Supporting Information exhibit typical transfer and output characteristics of the hybrid phototransistor in the dark, respectively. The saturation hole mobility and current onoff ratio of the device were determined to be 1.13 cm2/V s and 2 × 105, respectively. The contact resistance (Rc) of hybrid perovskite NPs/C8-BTBT crystal array-based device and pure C8-BTBT crystal array-based device extracted by the transmission line method was 1.15 × 104 and 1.20 × 104 Ω cm, respectively (Figure S14, Supporting 7


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Information). These Rc values are comparable to the reported values for C8-BTBT crystal-based transistors.23,24 In addition, the closed Rc values for both devices demonstrates that the existence of perovskite NPs on the C8-BTBT crystal surface does not significantly influence the contact barrier of electrodes with the device. Photoresponse of the phototransistor was investigated under 550 nm light illumination (10 μW/cm2) at a source-drain voltage (Vds) of -50 V. Note that the phototransistor exhibits a persistent photocurrent, to be discussed later. To acquire a stable photocurrent, the measurements were conducted only after exposing the device to light for sufficient time (~200 s). Figure 2b shows that under light illumination the source-drain current (Ids) increases sharply and the threshold voltage (VT) shifts positively from -25.7 to 18.3 V, implying a prominent increase in carrier concentration. Figure 2c depicts the photoresponsivity (R) of the phototransistor as a function of gate voltage (Vg). R is defined by (Ipc-Idark)/P, where Ipc and Idark are photo- and dark-current respectively, and P is the power of incident light.25 When Vg decreases toward negative bias direction, R increases to reach a maximum value of 2.04 × 104 A/W at Vg = -60 V. Specific detectivity (D*), which characterizes the ability of the devices to detect the incident light signal, is another critical parameter for evaluating the photodetector’s performance. The noise current is the main factor that limits the D* of a photodetector. We assume that shot noise from dark current is the major contributor to the total noise. Accordingly, the D* of the photodetector is given by (A𝑓)0.5 𝐷 = (𝑖𝑛 𝑅) ∗

where A, f, and in are the effective area of the device, the electrical bandwidth, and the 8


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noise current, respectively.26 The D* of our hybrid phototransistor as a function of Vg is plotted in Figure S15, Supporting Information. At Vg of -16 V, a maximum D* of 2.09 × 1012 Jones is obtained for the hybrid phototransistor. The obtained D* value is comparable to some typical works on the pristine perovskite-based photodetectors and organic single crystal-based phototransistors (Table S1, Supporting Information).27-32 An operating voltage (for Vds or Vg) of a few tens of volts is now needed for the phototransistor, which is typical for organic phototransistors.33,34 Nevertheless, we expect that the operating voltage can be reduced by using a high-k dielectric.35,36 Figure 2d shows that the phototransistor reveals selective response in the UV-Vis range, i.e. the device is sensitive to 500 nm and 300 nm light, but insensitive to NIR 900 nm and deep-UV (DUV) 200 nm light. The light wavelength-dependent R in Figure 2e reveals a response range of 252-780 nm, which is consistent with the absorption spectrum of the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array (Figure 1e). Notably, in the UV-Vis range, R is greater than 1.72 × 104 A/W, revealing the high device performance. Interestingly, although the content of CH3NH3PbI3 NPs is much less than that of C8-BTBT single crystals in the hybrid structure, the phototransistor shows similar R values in the entire UV-Vis range, which is very desirable for the broadband photodetection. This could be attributed to the fact that the absorption coefficient of CH3NH3PbI3 in the Vis range is nearly ten times higher than that of the C8-BTBT in the UV range.37,38 To gain statistical significance, the R values of over 50 devices were measured under 550 nm light illumination (10 μW/cm2) and shown as histogram in Figure S16, Supporting Information. It is found that the R of devices falls 9


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within a narrow range of 1.9 × 104 to 2.15 × 104 A/W with an average value of 2.02 × 104 A/W. The narrow distribution of R values clearly demonstrates the high uniformity of the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array. Significantly, the R value of our device is substantially larger than that of other perovskite-based photodetectors and OSSC-based phototransistors (Table S1, Supporting Information). Further, the hybrid phototransistor also exhibits the best performance for all broadband photodetectors (Table S2, Supporting Information).39-43 The high photoresponsivity of the hybrid phototransistors can be attributed to the single-crystalline structure of CH3NH3PbI3 NPs, ultra-long carrier life time in C8-BTBT crystals, and high interface quality of the hybrid structure that facilitates the photocarrier transfer and extraction. Note that the CH3NH3PbI3 NPs are discretely distributed on the C8-BTBT surface, ensuring the concurrent light illumination on the perovskite and organic crystals. The wide bandgap of C8-BTBT suggests that the UV photoresponse of the phototransistors is predominantly due to the UV absorption of the C8-BTBT single crystal array. Under UV illumination, electron-hole (e-h) pairs are primarily generated in the C8-BTBT single crystals (Figure 3a), and then separated by the electric field in the normal direction of device channel due to the application of a large Vg. The holes are restricted in a narrow region close to the BCB/C8-BTBT interface by the electric field, while the electrons are captured inside the C8-BTBT due to the strong electron trapping capability (Figure 3b).5 Consequently, recombination of holes and electrons is significantly reduced, thereby leading to a high photocurrent. Photoconductive gain (G) of the device can be estimated by the following equation: G = R × Ehv = τlifetime/τtransit, 10


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where τtransit is the transit time of the carriers through the device channel, τlifetime is the lifetime of the carriers, and Ehv is the incident photon energy. G of the hybrid phototransistor is estimated to be ~9 × 104 from the R value of the phototransistor in the UV range. Meanwhile, τtransit of holes is around 85 ns (based on the extracted mobility of 1.13 cm2/V s, a channel length of 20 µm, and an applied bias Vds of -50 V). Therefore, the τlifetime can be calculated to be 76.5 ms in C8-BTBT. The ultra-long τlifetime of holes can be attributed to the high crystal quality and the strong electron trapping capability of the C8-BTBT single crystals. Owing to the large τlifetime, multiple holes would circulate within the C8-BTBT single crystal channel following the generation of a single e-h pair by the incident photon, resulting in a high photoconductive gain. Different from the UV response, the high-sensitivity photoresponse of the hybrid phototransistors in the Vis light range derives from the synergy effect of the perovskite NPs and organic crystal array. Figure 3c illustrates the hybrid structure of the singlecrystalline CH3NH3PbI3 NPs on the surface of C8-BTBT single crystals. Upon Vis light illumination, electrons and holes are generated in the light-absorbing CH3NH3PbI3 NPs. Based on the energy band diagram in Figure 3d, the holes quickly transfer from the perovskite NPs to C8-BTBT single crystals and then drift to the drain electrode under the source-drain voltage, while the electrons remain trapped in the perovskite NPs due to the large energy barrier (2.5 eV) between the conduction band minimum (CBM) of CH3NH3PbI3 and the lowest unoccupied molecular orbital (LUMO) of C8-BTBT. In this case, a negative potential is generated by the electrons, resulting in a hole accumulation in the C8-BTBT channel through capacitive coupling. This light11


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triggered charge transfer process is of vital importance in enabling the hybrid structure for Vis light detection. The high R value obtained under Vis light illumination is attributed to the single-crystalline structure of CH3NH3PbI3 NPs, which possess high light-harvesting efficiency, and long carrier diffusion length and lifetime. As a result, more carriers are generated in the CH3NH3PbI3 NPs, leading to an ultra-high R value in the Vis light range. We investigated the charge transfer between perovskite NPs and C8-BTBT single crystals using in-suit Kelvin probe force microscopy (KPFM) measurements (Figure 4a). The topography scanning in Figure 4b shows the presence of one perovskite NP on the C8-BTBT surface. Figures 4c and 4d show the surface potential distribution of the hybrid structure in dark and under light illumination, respectively. It is observed that upon white light exposure, the surface potential difference between C8-BTBT single crystal and perovskite NP is increased by 2.1 mV compared to that measured in dark (Figure S17, Supporting Information). This directly verifies that the photogenerated electrons are accumulated in the perovskite NP under light illumination. The charge transfer process was further clarified by means of steady-state photoluminescence (PL) measurements (Figure S18, Supporting Information). The pristine CH3NH3PbI3 NPs show an intense emission centered at 773 nm, which is consistent with previous report.15,17 However, in the presence of C8-BTBT, an obvious quenching of the PL intensity could be observed for the hybrid CH3NH3PbI3 NPs/C8-BTBT crystal array, because of the strong charge transfer between perovskite NPs and C8-BTBT crystals. Light intensity-dependent photoresponse of the hybrid phototransistors was 12


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measured under 550 nm light illumination with different light intensities of 5, 10, 15, 20, 30, 35, 60 and 80 μW/cm2 at Vds = -50 V (Figure S19a, Supporting Information). The photocurrent increases significantly with increasing light intensity, along with an obvious positive shift of VT. Figure S19b (Supporting Information) plots the light intensity-dependent photocurrent at Vg = -60 V. Note that the photocurrent shows a nearly linear relationship with light intensity from 5 to 30 μW/cm2. Nevertheless, when the light intensity is above 30 μW/cm2, the photocurrent tends to deviate from the linear relationship, due to the saturation of charge carriers in the conducting channel under high light intensity. On the other hand, owing to the ultrahigh photoresponsivity, photocurrent still can remain as high as 8 μA at a low light intensity of 1 µW/cm2, revealing the potential of the hybrid device for weak light detection. The performance of the phototransistors also depends on the density of CH3NH3PbI3 NPs on the surface of C8-BTBT single crystal. In control experiments, hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal arrays with different surface densities of CH3NH3PbI3 NPs were fabricated by using NPs with concentration of 7, 9, 10.5, 12.5, and 14 mg/mL, respectively, in the solution (Figure S20, Supporting Information). From the optical images (Figure S20a-c, Supporting Information), the surface density of perovskite NPs tends to increase with increasing concentration of CH3NH3PbI3 NPs. However, the C8-BTBT single crystals become discontinuous when the concentration of CH3NH3PbI3 NPs is higher than 10.5 mg/mL. It suggests that mixing of CH3NH3PbI3 NPs in the solution would also impact the nucleation and growth of C8-BTBT single crystals. Figure S20d in Supporting Information plots the 13


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dependence of R on CH3NH3PbI3 NPs concentration under 550 nm light illumination. With increasing concentration of CH3NH3PbI3 NPs from 7 to 10.5 mg/mL, R increases gradually from 1.15 × 104 to 1.9 × 104 A/W, while the hole mobility of the devices changes slightly from 1.03 to 1.16 cm2/Vs. The enhancement of light absorption in the Vis light range with increasing density of perovskite NPs is responsible for the improved photosensitivity. However, when the NP concentration is higher than 10.5 mg/mL (e.g. 14 mg/mL), R decreases steeply to 835 A/W, while concurrently the hole mobility of the device also decreases sharply to 0.02 cm2/V s. This is because the crystallinity of organic crystals is seriously degraded at high NP concentration, leading to the reduced photosensitivity. Besides, the size of the perovskite NPs can affect the performance of the phototransistors. Perovskite NPs with average sizes of 100, 160, and 300 nm were prepared by altering the concentration of perovskite solution, as shown in Figure S21 in Supporting Information. Then hybrid CH3NH3PbI3 NPs/C8-BTBT crystal arrays with different sizes of CH3NH3PbI3 NPs were fabricated by using the same NPs concentration of 10.5 mg/mL. When the average size of CH3NH3PbI3 NPs is higher than 300 nm, it is observed that the C8-BTBT crystals become discontinuous, resulting in an obvious deterioration of the transistor performance. This means that the large NPs would affect the crystallization of the C8-BTBT crystals. However, when the average size of CH3NH3PbI3 NPs is at 160 nm or 100 nm, the R changes slightly, as shown in Figure S22, Supporting Information. On the other hand, the thickness of C8-BTBT single crystal also plays an important 14


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role in determining device performance. We prepared hybrid CH3NH3PbI3 NPs/C8BTBT single crystal arrays with different crystal thicknesses by altering the concentration of C8-BTBT during growth (Figure S23, Supporting Information). It is found that the devices exhibit similar performance when the crystal thickness is in the range of 40-120 nm. However, at a smaller thickness of 25 nm, the C8-BTBT crystal array becomes discontinuous, possibly due to the stronger influence of CH3NH3PbI3 NPs on thinner organic crystals. As a result, the hybrid device shows a poor device performance. Also, only a polycrystalline organic film can be obtained at a higher C8BTBT crystal thickness of 150 nm, resulting in the deterioration of device performance. Interestingly, we found that the photocurrent of hybrid transistors could be retained even after turning off the light. This phenomenon is known as persistent photocurrent and may have interesting applications in a variety of fields, such as bistable optical switches, light-triggered memory device, and radiation detectors.13 Figure 5a depicts the temporal response of the hybrid phototransistor under 550 nm light illumination (60 μW/cm2) at Vg = 10 V and Vds = -50 V. When the device was exposed to light, Ids increased quickly with time, but tended to saturate after ~240 s. Notably, after turning off the light, Ids would not disappear immediately, but decline slowly with time, revealing a pronounced persistent photocurrent. Under UV illumination, the device gave a similar phenomenon (Figure S24, Supporting Information). Although the persistent photocurrents were present for both UV and Vis light illumination, they actually originated from different mechanisms. Under UV light, photogenerated electrons would be trapped by the deep levels in C8-BTBT single 15


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crystals.5 Therefore, new holes were compensated from the source electrode neutralizing the trapped electrons. The slowly detrapping process of the electrons after turning off light would thus lead to the persistent photocurrent. We also examined the photoresponse characteristics of pure C8-BTBT single crystals (Figure S25, Supporting Information), and observed the persistent photocurrent as well, indicating that the persistent photocurrent is an intrinsic property of the C8-BTBT single crystals. Nevertheless, under Vis light, the persistent photocurrent most likely originated from the long carrier lifetime of perovskite NPs. The negatively charged perovskite NPs under Vis light illumination can induce positive carriers in the C8-BTBT single crystals. Owing to the long lifetime of the trapped electrons and a large energy barrier between the CH3NH3PbI3 NPs and the C8-BTBT single crystals for electron transfer, the device can remain in a high conduction state even after switching off the light, resulting in the persistent photocurrent. Note that the persistent photocurrent could be effectively eliminated by applying a large negative Vg of -60 V (Figure 5b), because the negative gate voltage can enable the escape of trapped electrons from the trapping levels of C8BTBT or the perovskite NPs. As a result, the device can quickly recover to the original low conduction state (10-11 A). Therefore, we can take advantage of this phenomenon to fabricate a light-triggered memory device.43 Figure 5b shows a series of writing/erasing cycles performed on the device, revealing excellent reproducibility. Also, the writing/erasing process can be investigated in the transfer characteristics of the device. Figure 5c shows that the device could be “erased” to the initial state by applying a Vg = -60 V for 1 s, and “re-written” with 550 nm light illumination to induce 16


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a large increase in Ids. Experiments on the device with UV light illumination (365 nm) give the similar result (Figure S26, Supporting Information). Moreover, the hybrid perovskite NPs/C8-BTBT single crystal array-based phototransistors show robust stability, as the transfer characteristics measured in dark and under light illumination remain nearly unchanged after exposing the device in air for 50 days (Figure 5d). The variations in mobility and R over 50 days were recorded and shown in Figure 5e, revealing that the mobility decreases slightly from 1.22 to 1.16 cm2/V s in the first 10 days, and then keeps constant (1.16 cm2/V s) afterwards. As a result, the corresponding R value is nearly unchanged in 50 days. The long-term stability of the hybrid perovskite NPs/C8-BTBT single crystal array should find applications in high-performance optoelectronic devices. We consider the following two features may contribute to the excellent device stability: (i) the single-crystalline perovskite NPs have fewer defects on the enclosing surfaces, which make the NPs more resistant to moisture in ambient air. (ii) C8-BTBT is composed of the robust benzothiophene, which also possesses excellent air stability.7,15 Due to the dual-band response, ultrahigh light sensitivity, and simple solutionprocessing capability, the hybrid perovskite NPs/C8-BTBT single crystal array-based phototransistors would have great potential for a variety of applications. In this work, we demonstrate the utility of the integrated phototransistors in secure communication. An array of 10 × 10 hybrid phototransistors was fabricated on a transparent quartz substrate, as described in Methods. The phototransistor arrays are addressable by applying a gate voltage on the gate electrode in each column (Figure 6a). We 17


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demonstrate a proof-of-concept device for secure communication purpose as follows. First, 50 nm thick C8-BTBT film was thermally deposited onto a quartz plate through a shadow mask with hollow “SOS” characters. Figure 6b shows that the profile of “SOS” characters is invisible under both Vis and UV light, indicating the “SOS” characters are successfully encrypted. To decrypt the information, the quartz plate encrypted with the “SOS” characters was placed on the phototransistors matrix, followed by UV light irradiation (Figure 6c). Since the patterned C8-BTBT film with the “SOS” characters could absorb UV light, the UV light transmitting through the C8-BTBT film would be attenuated. As a result, the current signals of the phototransistor pixels underneath the patterned C8-BTBT film are obviously lower than those of the pixels under light exposure. The output currents are reconstructed in a matrix form, which displays the encrypted information as the ‘‘SOS’’ characters (Figure 6d). The minimum required UV light intensity for decryption was further studied, as shown in Figure S27, Supporting Information. When the UV light intensity is under 1 μW/cm2, the encrypted “SOS” symbol cannot be identified anymore. This is reasonable because the lowest detectable UV light intensity for our hybrid transistor is about 1 μW/cm2 (Figure S19c,d, Supporting Information). In addition, the output currents of each device unit under Vis light are also recorded to form the image map (Figure 6e). However, the actual image (‘‘SOS’’) cannot be read out under Vis light, because the C8-BTBT film has a transparency of >90% in the Vis range (Figure S28, Supporting Information). In principle, if the Vis light intensity is strong enough, the photocurrent difference between the device underneath the patterned C8-BTBT film and the device under light 18


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exposure may become large enough to make the information decryption. Fortunately, we note that the photocurrent of the hybrid perovskite NPs/C8-BTBT single crystal array-based phototransistors tends to saturate when the Vis light intensity is above 80 μW/cm2 (Figure S19, Supporting Information). Therefore, even a higher Vis light intensity can hardly decrypt the information. Interestingly, owing to the persistent photocurrent behavior of the hybrid perovskite NPs/C8-BTBT crystal array, the characters of ‘‘SOS’’ remained visible even after UV light removal, making it possible to store the encrypted information by the phototransistor array at the same time. Also, the encrypted information can be immediately erased by applying a negative gate voltage on the phototransistors. These results demonstrate the potential of the hybrid perovskite NPs/C8-BTBT single crystal array-based phototransistors as dual-band photosensitive elements with memory functionality for secure communication application. CONCLUSION We present a simple, one-step solution-processing strategy to fabricate the hybrid structure of single-crystalline CH3NH3PbI3 NPs coated to C8-BTBT single crystal array, which can be made into high-sensitivity phototransistors with dual-band capability. The single-crystalline CH3NH3PbI3 NPs in the hybrid broaden the spectral response of the pristine C8-BTBT single crystals from single-band (UV) to dual-band (UV-Vis) via effective charge transfer, giving rise to pronounced photoresponse of the hybrid device in the Vis range. In-suit KPFM measurements verified the charge transfer from perovskite NPs to C8-BTBT single crystals under Vis light. Phototransistors fabricated 19


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from the hybrid perovskite NPs/C8-BTBT single crystal array possess an ultrahigh responsivity of >1.72 × 104 A/W in the entire dual-band region of 252-780 nm with robust stability of >50 days in air. Benefiting from the high uniformity of the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array, the corresponding 50 devices exhibit a narrow R distribution from 1.9 × 104 to 2.15 × 104 A/W with an average value of 2.02 × 104 A/W. The present hybrid device possesses the best performance of all solutionprocessing, broadband photodetectors. Moreover, a 10 × 10 phototransistor matrix made of the hybrid perovskite NPs/C8-BTBT single crystal array shows potential for secure communication applications.

METHODS Materials and solution preparation. CH3NH3PbI3 was purchased from Xi'an Polymer Light Technology Corp (http://www.p-oled.cn). C8-BTBT was provided by Luminescence Technology Corp. All materials were used as received. Modification of silicon substrates. Firstly, N-type Si substrates were cleaned with H2SO4, acetone, and deionized water in sequence for 10 min, respectively, and further treated by uv-ozone cleaner for 600 s. Then BCB solution was spin-coated onto the Si substrates at 2000 rpm for 20 s and then annealed at 220 °C for 60 min. Synthesis and characterizations of CH3NH3PbI3 NPs. In a typical synthesis of CH3NH3PbI3 NPs, a 10 µL solution containing 0.05 M CH3NH3PbI3 in dimethylformamide (DMF) was added into 10 mL dichloromethane (CH2Cl2) at room temperature under vigorous stirring to produce a fulvous solution. The brown-black 20


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solution product was centrifuged at 7000 rpm for 15 min to obtain CH3NH3PbI3 NPs precipitates. Then the perovskite NPs were redispersed into C8-BTBT/CH2Cl2 solution (4 mg/mL). The morphologies of the NPs were characterized by SEM (FEI, Model Quanta 200 FEG) and TEM (FEI, Model Tecnai G2 F20). The crystallography of the NPs was detected using an XRD (Empyrean) and TEM (FEI, Model Tecnai G2 F20) operated at an acceleration voltage of 200 kV with selected-area electron diffraction (SAED). The UV-Vis absorption spectrum was measured using a UV/Vis/NIR spectrophotometer (Perkin Elmer, Model Lambda 750). Growth and characterizations of hybrid perovskite NPs/C8-BTBT crystal array. To fabricate the perovskite NPs/C8-BTBT single crystal array, a Si substrate covered with 300 nm BCB layer was dipped into perovskite NPs/C8-BTBT/CH2Cl2 solution and then withdrawn at a constant rate of 90 μm/s. Morphologies of the resultant hybrid perovskite NPs/C8-BTBT single crystal arrays were characterized using an optical microscope (Leica, DM4000M) and AFM (Veeco, MultiMode V). Crystallinity of the hybrid CH3NH3PbI3 NPs/single-crystalline C8-BTBT array was determined by XRD. The absorption of hybrid CH3NH3PbI3 NPs/single-crystalline C8-BTBT array was detected by UV/Vis/NIR spectrophotometer. Fabrication and measurements of the photodetectors. To fabricate the hybrid phototransistors, 50 nm gold source-drain electrodes were thermally evaporated on the hybrid CH3NH3PbI3 NPs/single-crystalline C8-BTBT array through a shadow mask. The channel length and width of the devices were 20 µm and 125 µm, respectively. Electrical measurements on the devices were conducted by using a semiconductor 21


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characterization system (Keithley, Model 4200) on a probe station (EverBeing, PE4). Monochromatic light provided by a Xenon lamp coupled to a monochromator (Zolix Omni-λBright300) was used as a light source to illuminate the photodetector from the top. The light intensity reaching the device surface was modulated by adjusting the slit width. The light intensity was calibrated with a standard silicon photodiode (Newport, 918D-UV-OD3R). All phototransistors were measured after light illumination for an adequate time (~200 s) to acquire a stable photocurrent. The mobility was extracted from the saturation region according to the equation of 2𝐿 ∂ 𝐼ds 𝜇sat = 𝑊𝐶i ∂𝑉g

2

( )

Where μsat is the saturation mobility and Ci is the dielectric capacitance per unit area.44 Fabrication of hybrid phototransistor arrays. To construct the phototransistor arrays, 100 nm Al gate electrodes were firstly deposited onto the substrate through a shadow mask via thermal evaporation. Subsequently, BCB dielectric films were fabricated by spin coating a BCB solution at 3000 rpm for 1 min. The resultant films were dried at 200 °C in air overnight. Then, hybrid perovskite NPs/C8-BTBT single crystal array was deposited on the substrate via dip-coating. Interdigitated Au sourcedrain electrodes (65 nm) were evaporated through a shadow mask at a pressure of 106 mbar

and a rate of 0.45 Å/s. The channel length and width of the phototransistors were

50 and 4000 µm, respectively. Each pixel in the hybrid phototransistor array was measured manually.

ASSOCIATED CONTENT 22


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Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Performance statistics for the reported phototransistors. Some of the most widely adopted π-conjugated organic small molecules in phototransistors. Characterizations of C8-BTBT, CH3NH3PbI3 NPs, and hybrid CH3NH3PbI3 NPs/C8-BTBT structure. Frequency-capacitance curve of the BCB dielectric layer. Performance of the hybrid perovskite NPs/C8-BTBT single crystal array-based phototransistors.

AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected], [email protected], [email protected] Author Contributions X. Z. Xu and W. Deng contribute equally to this work. The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

ACKNOWLEDGMENTS This work was supported by the National Basic Research Program of China (Grant No. 2016YFA0202400), the National Natural Science Foundation of China (Grant Nos. 51672180, 51622306, 51821002, 91833303, and 21673151), Natural Science Foundation of Jiangsu Province of China (BK20180845), Qing Lan Project, 111 project, Collaborative Innovation Center of Suzhou Nano Science and Technology (Nano-CIC) 23


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and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). REFERENCES (1) Liu, H. C.; Song, C. Y.; Shen, A.; Gao, M.; Dupont, E.; Poole, P. J.; Wasilewski, Z. R.; Buchanan, M.; Wilson, P. H.; Robinson, B. J.; Thompson, D. A.; Ohno, Y.; Ohno, H. Dual-Band Photodetectors Based on Interband and Intersubband Transitions. Infrared Phys. Technol. 2001, 42, 163-170. (2) Deng, W.; Jie, J. S.; Shang, Q. X.; Wang, J. C.; Zhang, X. J.; Yao, S. W.; Zhang, Q.; Zhang, X. H. Organic Nanowire/Crystalline Silicon P–N Heterojunctions for HighSensitivity, Broadband Photodetectors. ACS Appl. Mater. Interfaces 2015, 7, 20392045. (3) Wang, P.; Liu, S. S.; Luo, W. J.; Fang, H. H.; Gong, F.; Guo, N.; Chen, Z. G.; Zou, J.; Huang, Y.; Zhou, X. H.; Wang, J. L.; Chen, X. S.; Lu, W.; Xiu, F. X.; Hu, W. D.. Arrayed Van Der Waals Broadband Detectors for Dual-Band Detection. Adv. Mater. 2017, 29, 1604439. (4) Wu, Y.; Li, X. M.; Wei, Y.; Gu, Y.; Zeng, H. B. Perovskite Photodetectors with Both Visible-Infrared Dual-Mode Response and Super-Narrowband Characteristics towards Photo-Communication Encryption Application. Nanoscale 2018, 10, 359-365. (5) Yuan, Y. B.; Huang, J. S. Ultrahigh Gain, Low Noise, Ultraviolet Photodetectors with Highly Aligned Organic Crystals. Adv. Opt. Mater. 2016, 4, 264-270. (6) Deng, W.; Zhang, X. J.; Wang, L.; Wang, J. C.; Shang, Q. X.; Zhang, X. H.; Huang, L. M.; Jie, J. S. Wafer-Scale Precise Patterning of Organic Single-Crystal Nanowire 24


Page 25 of 38 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Arrays via a Photolithography-Assisted Spin-Coating Method. Adv. Mater. 2015, 27, 7305-7312. (7) Reese, C.; Bao, Z. N. Organic Single-Crystal Field-Effect Transistors. Mater. Today 2007, 10, 20-27. (8) Deng, W.; Zhang, X. J.; Dong, H. L.; Jie, J. S.; Xu, X. Z.; Liu, J.; He, L.; Xu, L.; Hu, W. P.; Zhang, X. H. Channel-Restricted Meniscus Self-Assembly for Uniformly Aligned Growth of Single-Crystal Arrays of Organic Semiconductors. Mater. Today. 2019, 24, 17-25. (9) Song, I.; Lee, S. C.; Shang, X. B.; Ahn, J.; Jung, H. J.; Jeong, C. U.; Kim, S. W.; Yoon, W.; Yun, H.; Kwon, O. P.; Oh, J. H. High-Performance Visible-Blind UV Phototransistors Based on N-Type Naphthalene Diimide Nanomaterials. ACS Appl. Mater. Interfaces 2018, 10, 11826-11836. (10) Smithson, C. S.; Wu, Y. L.; Wigglesworth, T.; Zhu, S. P. A More Than Six Orders of Magnitude UV-Responsive Organic Field-Effect Transistor Utilizing a Benzothiophene Semiconductor and Disperse Red for Enhanced Charge Separation. Adv. Mater. 2015, 27, 228-233. (11) Jones, G. F.; Pinto, R. M.; De Sanctis, A.; Nagareddy, V. K.; Wright, C. D.; Alves, H.; Craciun, M. F.; Russo, S. Highly Efficient Rubrene-Graphene Charge-Transfer Interfaces as Phototransistors in the Visible Regime. Adv. Mater. 2017, 29, 1702993. (12) Ahn, S. E.; Song, I.; Jeon, S.; Jeon, Y. W.; Kim, Y.; Kim, C.; Ryu, B.; Lee, J. H.; Nathan, A.; Lee, S.; Kim, G. T.; Chung, U. I. Metal Oxide Thin Film Phototransistor for Remote Touch Interactive Displays. Adv. Mater. 2012, 24, 2631-2636. 25


ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 38

(13) Seo, J. H.; Zhang, K.; Kim, M.; Zhao, D. Y.; Yang, H. J.; Zhou, W. D.; Ma, Z. Q. Flexible Phototransistors Based on Single-Crystalline Silicon Nanomembranes. Adv. Opt. Mater. 2016, 4, 120-125. (14) Jung, J. H.; Yoon, M. J.; Lim, J. W.; Lee, Y. H.; Lee, K. E.; Kim, D. H.; Oh, J. H. High-Performance UV-Vis-NIR Phototransistors Based on Single-Crystalline Organic Semiconductor-Gold Hybrid Nanomaterials. Adv. Funct. Mater. 2017, 27, 1604528. (15) Deng, W.; Zhang, X. J.; Huang, L. M.; Xu, X. Z.; Wang, L.; Wang, J. C.; Shang, Q. X.; Lee, S. T.; Jie, J. S. Aligned Single-Crystalline Perovskite Microwire Arrays for High-Performance Flexible Image Sensors with Long-Term Stability. Adv. Mater. 2016, 28, 2201-2208. (16) Deng, W.; Xu, X. Z.; Zhang, X. J.; Zhang, Y. D.; Jin, X. C.; Wang, L.; Lee, S. T.; Jie, J. S. Organometal Halide Perovskite Quantum Dot Light-Emitting Diodes. Adv. Funct. Mater. 2016, 26, 4797-4802. (17) Deng, W.; Huang, L. M.; Xu, X. Z.; Zhang, X. J.; Jin, X. C.; Lee, S. T.; Jie, J. S. Ultrahigh-Responsivity Photodetectors from Perovskite Nanowire Arrays for Sequentially Tunable Spectral Measurement. Nano Lett. 2017, 17, 2482-2489. (18) Gu, L. L.; Tavakoli, M. M.; Zhang, D. Q; Zhang, Q. P; Waleed, A.; Xiao, Y. Q.; Tsui, K. H.; Lin, Y. J.; Liao, L.; Wang, J. N.; Fan, Z. Y. 3D Arrays of 1024-Pixel Image Sensors Based on Lead Halide Perovskite Nanowires. Adv. Mater. 2016, 28, 9713-9721. (19) Senanayak, S. P.; Yang, B. Y.; Thomas, T. H.; Giesbrecht, N.; Huang, W. C.; Gann, E.; Nair, B.; Goedel, K.; Guha, S.; Moya, X.; McNeill, C. R.; Docampo, P.; 26


Page 27 of 38 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Sadhanala, A.; Friend, R. H.; Sirringhaus, H.. Understanding Charge Transport in Lead Iodide Perovskite Thin-Film Field-Effect Transistors. Sci. Adv. 2017, 3, 1-11. (20) Shao, Y. C.; Liu, Y.; Chen, X. L.; Chen, C.; Sarpkaya, I.; Chen, Z. L.; Fang, Y. J.; Kong, J.; Watanabe, K.; Taniguchi, T.; Taylor, A.; Huang, J. S.; Xia, F. N. Stable Graphene-Two-Dimensional Multiphase Perovskite Heterostructure Phototransistors with High Gain. Nano Lett. 2017, 17, 7330-7338. (21) Peng, B.; Yu, G. N.; Zhao, Y. W.; Xu, Q.; Xing, G. C.; Liu, X. F.; Fu, D. Y.; Liu, B.; Tan, J. R. S.; Tang, W.; Lu, H. P.; Xie, J. L.; Deng, L. J.; Sum, T. C.; Loh, K. P.. Achieving Ultrafast Hole Transfer at the Monolayer MoS2 and CH3NH3PbI3 Perovskite Interface by Defect Engineering. ACS Nano 2016, 10, 6383-6391. (22) Wang, Y.; Fullon, R.; Acerce, M.; Petoukhoff, C. E.; Yang, J.; Chen, C. G.; Du, S. N.; Lai, S. K.; Lau, S. P.; Voiry, D.; O’Carroll, D.; Gupta, G.; Mohite, A. D.; Zhang, S. D.; Zhou, H.; Chhowalla, M. Solution-Processed MoS2/Organolead Trihalide Perovskite Photodetectors. Adv. Mater. 2017, 29, 1603995. (23) Minari, T.; Darmawan, P.; Liu, C.; Li, Y.; Xu, Y.; Tsukagoshi, K. Highly Enhanced Charge Injection in Thienoacene-Based Organic Field-Effect Transistors with Chemically Doped Contact. Appl. Phys. Lett. 2012, 100, 93303-93307. (24) Liu, C.; Xu, Y.; Noh, Y. Y. Contact Engineering in Organic Field-Effect Transistors. Mater. Today, 2015, 18, 79-97. (25) Zeng, L. H.; Wang, M. Z.; Hu, H.; Nie, B.; Yu, Y. Q.; Wu, C. Y.; Wang, L.; Hu, J. G.; Xie, C.; Liang, F. X.; Luo, L. B.. Monolayer Graphene/Germanium Schottky Junction As High-Performance Self-Driven Infrared Light Photodetector. ACS Appl. 27


ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 38

Mater. Interfaces 2013, 5, 9362-9366. (26) Xie, C.; Wang, Y.; Zhang, Z. X.; Wang, D.; Luo, L. B. Graphene/Semiconductor Hybrid Heterostructures for Optoelectronic Device Applications. Nano Today 2018, 19, 41–83. (27) Lee, Y.; Kwon, J.; Hwang, E.; Ra, C. H.; Yoo, W. J.; Ahn, J. H.; Park, J. H.; Cho, J. H. High-Performance Perovskite-Graphene Hybrid Photodetector. Adv. Mater. 2015, 27, 41-46. (28) Peng, Z. Y.; Xu, J. L.; Zhang, J. Y.; Gao, X.; Wang, S. D. Solution-Processed High-Performance Hybrid Photodetectors Enhanced by Perovskite/MoS2 Bulk Heterojunction. Adv. Mater. Interfaces 2018, 5, 1800505. (29) Li, F.; Wang, H.; Kufer, D.; Liang, L. L.; Yu, W. L.; Alarousu, E.; Ma, C.; Li, Y. Y.; Liu, Z. X.; Liu, C. X.; Wei, N. N.; Wang, F.; Chen, L.; Mohammed, O. F.; Fratalocchi, A.; Liu, X. G.; Konstantatos, G.; Wu, T. Ultrahigh Carrier Mobility Achieved in Photoresponsive Hybrid Perovskite Films via Coupling with SingleWalled Carbon Nanotubes. Adv. Mater. 2017, 29, 1602432. (30) Dong, R.; Fang, Y.; Chae, J.; Dai, J.; Xiao, Z.; Dong, Q.; Yuan, Y.; Centrone, A.; Zeng, X. C.; Huang, J. High-Gain and Low-Driving-Voltage Photodetectors Based on Organolead Triiodide Perovskites. Adv. Mater. 2015, 27, 1912-1918. (31) Wang, G. M; Li, D. H.; Cheng, H. C.; Li, Y. J.; Chen, C. Y.; Yin, A. X.; Zhao, Z. P.; Lin, Z. Y.; Wu, H.; He, Q. Y.; Ding, M. N.; Liu, Y.; Huang, Y.; Duan, X. F. Wafer-Scale Growth of Large Arrays of Perovskite Microplate Crystals for Functional Electronics and Optoelectronics. Sci. Adv. 2015, 1, 1500613. 28


Page 29 of 38 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

(32) Guo, Y.; Du, C.; Yu, G.; Di, C.; Jiang, S.; Xi, H.; Zheng, J.; Yan, S.; Yu, C.; Hu, W.; Liu, Y. High-Performance Phototransistors Based on Organic Microribbons Prepared by a Solution Self-Assembly Process. Adv. Funct. Mater. 2010, 20, 10191024. (33) Wang, W.; Wang, L.; Dai, G. L.; Deng, W.; Zhang, X. J.; Jie, J. S.; Zhang, X. H. Controlled Growth of Large-Area Aligned Single-Crystalline Organic Nanoribbon Arrays for Transistors and Light-Emitting Diodes Driving. Nano-Micro Lett. 2017, 9, 52. (34) Ji, D.; Li, T.; Liu, J.; Amirjalayer, S.; Zhong, M.; Zhang, Z.; Huang, X.; Wei, Z.; Dong, H.; Hu, W.; Fuchs, H. Band-like Transport in Small-Molecule Thin Films toward High Mobility and Ultrahigh Detectivity Phototransistor Arrays. Nat. Commun. 2019, 10, 12. (35) Xu, W.; Rhee, S. W. Low-Operating Voltage Organic Field-Effect Transistors with High-k Cross-Linked Cyanoethylated Pullulan Polymer Gate Dielectrics. J. Mater. Chem. 2009, 19, 5250. (36) Shahin, D. I.; Tadjer, M. J.; Wheeler, V. D.; Koehler, A. D.; Anderson, T. J.; Eddy, C. R.; Christou, A. Electrical Characterization of ALD HfO2 High-k Dielectrics on (201) β-Ga2O3. Appl. Phys. Lett. 2018, 112, 042107. (37) De Wolf, S.; Holovsky, J.; Moon, S. J.; Löper, P.; Niesen, B.; Ledinsky, M.; Haug, F. J.; Yum, J. H.; Ballif, C. Organometallic Halide Perovskites: Sharp Optical Absorption Edge and Its Relation to Photovoltaic Performance. J. Phys. Chem. Lett. 2014, 5, 1035–1039. 29


ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 38

(38) Keum, C. M.; Liu, S.; Al-Shadeedi, A.; Kaphle, V.; Callens, M. K.; Han, L.; Neyts, K.; Zhao, H.; Gather, M. C.; Bunge, S. D.; Twieg, R. J.; Jakli, A.; Lüssem, B.. Tuning Charge Carrier Transport and Optical Birefringence in Liquid-Crystalline Thin Films: A New Design Space for Organic Light-Emitting Diodes. Sci. Rep. 2018, 8 , 699. (39) Gong, X.; Tong, M. H.; Xia, Y. J.; Cai, W. Z.; Moon, J. S.; Cao, Y.; Yu, G.; Shieh, C. L.; Nilsson, B.; Heeger, A. J. High-Detectivity Polymer Photodetectors with Spectral Response from 300 nm to 1450 nm. Science 2009, 325, 1665-1667. (40) Chen, S.; Teng, C. J.; Zhang, M.; Li, Y. R.; Xie, D.; Shi, G. Q. A Flexible UVVis-NIR Photodetector Based on a Perovskite/Conjugated-Polymer Composite. Adv. Mater. 2016, 28, 5969-5974. (41) Shen, L.; Lin, Y. Z.; Bao, C. X.; Bai, Y.; Deng, Y. H.; Wang, M. M.; Li, T.; Lu, Y. F.; Gruverman, A.; Li, W. W.; Huang, J. S. Integration of Perovskite and Polymer Photoactive Layers to Produce Ultrafast Response, Ultraviolet-to-near-Infrared, Sensitive Photodetectors. Mater. Horizons 2017, 4, 242-248. (42) Qi, Z.; Cao, J. M.; Li, H.; Ding, L. M.; Wang, J. Z. High-Performance Thermally Stable Organic Phototransistors Based on PSeTPTI/PC61BM for Visible and Ultraviolet Photodetection. Adv. Funct. Mater. 2015, 25, 3138-3146. (43) Han, H.; Nam, S.; Seo, J.; Lee, C.; Kim, H.; Bradley, D. D. C.; Ha, C. S.; Kim, Y. Broadband All-Polymer Phototransistors with Nanostructured Bulk Heterojunction Layers of NIR-Sensing N-Type and Visible Light-Sensing P-Type Polymers. Sci. Rep. 2015, 5, 16457. 30


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(44) Paterson, A. F.; Singh, S.; Fallon, K. J.; Hodsden, T.; Han, Y.; Schroeder, B. C.; Bronstein, H.; Heeney, M.; McCulloch, I.; Anthopoulos, T. D. Recent Progress in HighMobility Organic Transistors: A Reality Check. Adv. Mater. 2018, 30, 1801079.

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Figure 1. (a) Polarized optical microscope images of CH3NH3PbI3 NPs on the surfaces of C8-BTBT single crystal array. (b) AFM observation of the hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal. (c) TEM image of the hybrid CH3NH3PbI3 NPs/C8BTBT single crystal. (d) XRD pattern and (e) UV-Vis absorption spectrum of hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array.

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Figure 2. (a) Schematic illustration of hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal array-based phototransistor. (b) Transfer characteristics (Vds = -50 V) of the hybrid phototransistor in dark and under 550 nm light illumination (10 μW/cm2). (c) Photoresponsivity of the perovskite NPs/C8-BTBT hybrid phototransistor as a function of Vg. Vds was fixed at -50 V. (d) Transfer characteristics of the hybrid perovskite NPs/C8-BTBT single crystal array-based phototransistor in dark and under light of different wavelengths. Light intensity was fixed at 10 μW/cm2. (e) Photoresponsivity as a function of light wavelength. Light intensity was fixed at 10 μW/cm2. Vds and Vg were fixed at -50 V and -60 V, respectively.

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Figure 3. (a, b) Schematic illustration of the operating mechanism of the hybrid phototransistor under UV illumination. (c) Schematic illustration of the hybrid structure, composed of single-crystalline CH3NH3PbI3 NPs on the surface of C8-BTBT single crystals. (d) Light-triggered charge transfer process from CH3NH3PbI3 to C8-BTBT.

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ACS Nano

Figure 4. (a) Schematic illustration of the KPFM setup. (b) AFM topographic image of the hybrid CH3NH3PbI3 NP/C8-BTBT single crystal. Surface potential distribution of hybrid CH3NH3PbI3 NPs/C8-BTBT single crystal (c) in the dark and (d) under the white light illumination, respectively.

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Figure 5. (a) Temporal response of the hybrid perovskite NPs/C8-BTBT single crystal array-based phototransistor under 550 nm light illumination (60 μW/cm2) at Vg = 10 V and Vds = -50 V. (b) Four representative programming and erasing cycles of the device. The device was programmed under 550 nm light illumination (60 μW/cm2) at Vg = 10 V and Vds = -50 V, while was erased by applying a gate pulse at -60 V for 1 s. (c) Transfer characteristics of the hybrid phototransistor during programming and erasing cycles. (d) Long-term stability of the hybrid phototransistor. The transfer characteristics were measured in the dark and under 550 nm light illumination (10 μW/cm2), respectively. (e) Variation of mobility and R with time for the hybrid phototransistor in ambient air at ~10-25% humidity.

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ACS Nano

Figure 6. (a) Schematic illustration of a large-area matrix of phototransistor array with 10 × 10 pixels. (b) Vis and UV imaging results of encrypting “SOS” characters, respectively. (c) Schematic illustration of the measurement configuration for examining the capability of the integrated phototransistors in secure communication application. The intensity of transmission light in UV range was weakened by the C8-BTBT film with shape of ‘‘SOS’’ on the quartz plate, while the intensity of transmission light in Vis light intensity was nearly unchanged. (d, e) Output results of decryption by the dual-band phototransistor arrays under UV and Vis lights, respectively.

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TOC Figure

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Dual-Band, High-Performance Phototransistors from Hybrid Perovskite

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