Compliance-Free Multileveled Resistive Switching in a Transparent

Subscriber access provided by UNIVERSITY OF TOLEDO LIBRARIES

Functional Inorganic Materials and Devices

Compliance Free Multileveled Resistive Switching in transparent 2D Perovskite for Neuromorphic Computing Mohit Kumar, Hong-Sik Kim, Dae Young Park, Mun Seok Jeong, and Joondong Kim ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b19406 • Publication Date (Web): 29 Mar 2018 Downloaded from http://pubs.acs.org on March 29, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 17 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 Applied Materials & Interfaces

Compliance Free Multileveled Resistive Switching in Transparent 2D Perovskite for Neuromorphic Computing Mohit Kumar†, ^, Hong-Sik Kim†, ^, #, Dae Young Park#, Mun Seok Jeong*,# and Joondong Kim*,†,^

†

Photoelectric and Energy Device Application Lab (PEDAL), Multidisciplinary Core Institute for Future Energies (MCIFE), Incheon National University, 119 Academy Rd. Yeonsu, Incheon, 22012, Republic of Korea ^

Department of Electrical Engineering, Incheon National University, 119 Academy Rd. Yeonsu, Incheon, 22012, Republic of Korea

#

Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea ABSTRACT: We demonstrate the pulsed voltage tunable multileveled resistive switching across a promising transparent energy material of (C4H9NH3)2PbBr4. The x-ray diffraction and scanning electron microscopy confirm the growth of (001) plane orientated nanostructures of (C4H9NH3)2PbBr4 with an average size of ~360 nm. The device depicts optical transmittance higher than 70% in visible region and efficient absorbance in the ultra-violet region. The currentvoltage measurement shows the bipolar resistive switching (RS). In addition, depending on the magnitude of applied electric pulse, the current across the device can be flipped in four different levels, which remain stable for long time, indicating multimode RS. Further, the current across the device increases gradually by applying continuous pulses, similarly to the biological synapses. The observed results are attributed to the electric field-induced ionic migration across the (C4H9NH3)2PbBr4. The existing study should open a new avenue to apply this promising energy material of perovskite for multi-functional advanced devices.

Keywords: Transparent; Perovskite energy material; Resistive switching; Multilevel; Neuromorphic. 1 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 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

1. INTRODUCTION With the outstanding physical properties, in comparison of both organic and inorganic materials, perovskite materials have grown a large attention in recent years and considered promising semiconductors for next-generation optoelectronic devices.1,2 Generally, these materials show an undesired hysteresis in the current-voltage (I–V) characteristics, which was utilized as an advantage to design a perovskite-based resistive switching (RS) memory.3,4,5,6,7 The RS behaviour in perovskite is explained by the electric field-induced ionic rearrangement, resulting in makes it more complicated in comparison to oxide-based RS memories. 3,7,8,9 On the other hand, due to ionic movement, one can expect that magnitude of the current across the perovskite can be tuned by choosing appropriate parameters such as pulsed electric field and its duration. Generally, the RS device initially shows one state of resistance at a fixed voltage, which can be flipped to the another one by applying an electric pulse, resulting in two-level operation.1,9,10 In addition, multilevel resistance values were also achieved by fixing the current compliance limit of the measuring device.3,8,11 For instance, Choi et al. have demonstrated the presence of multilevel RS in perovskite according to different current compliances.3 The perovskite-based RS device has a high potential for the multilevel controlled operation, however the promise is yet to be achieved. Among the family of perovskite materials, 2D layered organic−inorganic hybrid perovskites has a formula of (L)2(SMX3)n+1MX4, where L, S represent the long- and short-chain organic cations, M, and X correspond to a divalent metal cation, and a halide, respectively.12,13 In addition, n is the number of MX4 monolayers, sandwiched between two long-chain organic layers.12,13 Recently, layered 2D perovskites has been used to design extremely low operating

2 ACS Paragon Plus Environment

Page 2 of 17

Page 3 of 17 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


current RS memory for neuromorphic computing.12 In addition, it is worth to mention here that the band gap of the 2D layered (C4H9NH3)2PbBr4 is around 3.0 eV, which in turn opens the possibility to exploit it for highly visibly transparent electronic devices.14 Further, a transparent device that can show neuromorphic behaviour is also enormous important to design see-through computing devices and beyond. However, to the best of our knowledge, utilization of 2D layered perovskite materials for the highly transparent, stable, and multilevel RS device that also shows neuromorphic behaviour remains elusive so far. In this work we demonstrate the presence of multilevel resistive switching in nanostructured (C4H9NH3)2PbBr4 thin film. The nanostructure size distribution is carried out using scanning electron microscopy. The optical measurements are performed to observe the transmittance of the device and band gap of the (C4H9NH3)2PbBr4 thin film. Current-voltage measurements reveal the presence of bipolar-resistive switching. In addition, it is found that multileveled current conductance across the device can be achieved by choosing appropriate applied bias pulses. Further, it is demonstrated that the device shows a gradual increment in current by applying continuous pulses which in turn offers to use it for neuromorphic computing. The present study should open a new avenue to use transparent perovskite-based energy materials for advanced multilevel memory device.

2. EXPERIMENTAL SECTION 2.1 Deposition processes of ZnO and NiO layers. Prior to the device fabrication the FTOcoated glass substrate was ultrasonically cleaned sequentially in acetone, methanol and deionized water. Zinc oxide (ZnO) thin film was grown using a commercially available 99.99% pure ZnO target. Ultra-pure (99.999%) argon gas was injected into the chamber with a flow rate of 50 sccm



to maintain a working pressure of 5 mTorr during sputtering. An RF power of 300 W was applied to the ZnO target and the substrates were rotated with a speed of 5 rpm to achieve uniform film thickness. To form the top p-type NiO layer, a pure Ni target (purity, 99.999%) was reactive sputtered with simultaneous flowing of Ar (30 sccm) and O2 (4 sccm) gases. A DC power of 50 W was applied to the Ni target for 15 min at a working pressure of 3 mTorr. All metal oxides were deposited at room temperature. 2.2 Perovskite preparation. C4H9NH3Br (Buthylammonium bromide, BuABr) was purchased from Dyesol. PbBr2(Lead(II) bromide) and DMSO (dimethyl sulfoxide) were received from Aldrich. All chemicals were used without purification. To prepare the thin film, 0.75M (C4H9NH3)2PbBr4 Perovskite solution was prepared by dissolution of BuABr and PbBr2 in DMSO with 2:1 molar ratio. Solution kept for overnight with continuous stirring after then was filtered with PTFE syringe filter (0.2 µm). Perovskite film was formed after spin coating on ZnO-coated FTO substrate with 3000 rpm for 15 s and annealing at 100 ℃ for 10 minutes. 2.3 Characterization. The surface morphology of the device was observed using a field emission scanning electron microscope (FESEM, JEOL, JSM_7800F). Optical transmittance of the full device was carried out using an ultraviolet-visible-near-IR spectrophotometer (Shimadzu, UV-2600). A UV-Vis/NIR spectrophotometer (V-670, JASCO) was used in transmission geometry at room temperature to collect the absorbance spectra of (C4H9NH3)2PbBr4 film coated on glass substrate. Glass substrate was used as reference for baseline. Photoluminescence spectroscopy (PL) spectra of the perovskite film was collected using an NTEGRA Spectra instrument with a 355-nm laser excitation source. Powder X-ray diffraction (PXRD) was performed on an X-ray diffractometer (Rigaku, SmartLab) using Cu-Kα radiation (λ = 1.54059 Å). Bragg-Brentano focusing was performed at 45 kV and 200 mA with a tube. The electrical


Page 4 of 17

Page 5 of 17 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


characterization of the device was tested by potentiostat/galvanostat (ZIVE SP1, WonA Tech, Korea) measurement setup.

3. RESULTS AND DISCUSSION The schematic of the device is shown in Figure 1a, depicting the different layers. The presence of NiO and ZnO provide an air stable configuration to the device.1 A tilted-view scanning electron microscopy (SEM) image of the typical device is presented in Figure 1b, revealing the thickness and material distribution across the same. On the other hand, Figure 1c shows the planar-view SEM image of the (C4H9NH3)2PbBr4 thin film, which clearly depicts the presence of uniformly distributed nanostructures, having an average size of 360 nm. It is wellknown that the carrier density available for electrical transport in a material strongly depends on its crystallinity.10 Therefore, the x-ray diffraction (XRD) of the (C4H9NH3)2PbBr4 grown on a SiO2 substrate was performed. The XRD pattern exhibits prominent peak at 2θ=6.4° [Figure 1d] and the corresponding d-spacing matches well to the (001) plane of the 2D layered (C4H9NH3)2PbBr4 crystal.12,14 Further, the out-of-plane spacing (d) is about 1.42 nm, which matches well with previous report.14 To ensure the transparency, the measurements of the optical properties of the full device was performed. From the Figure 2a, one can note that the average transmittance of the device is greater than 70% in the entire visible range. In fact, as desired for see through applications, the device shows an excellent transmittance ~75% at a wavelength of 550 nm. In addition, the observed sharp decrease of the transmittance around 400 nm can be attributed to the fundamental absorption edge of (C4H9NH3)2PbBr4. The inset of the Figure 2a shows the original photograph of the full device that is indeed highly transparent and preserving the outside colour, to satisfy



the two major criteria to be applied it for see-through devices. An absorption and photoluminescence spectrum of (C4H9NH3)2PbBr4/glass are presented in Figure 2b. The (C4H9NH3)2PbBr4 shows good absorption in the UV range, indicating that this perovskite can be useful to design UV-based optoelectronics. In addition, the presence of a sharp peak around 405 nm in the PL spectra indicates that the band gap of the (C4H9NH3)2PbBr4 is ~3.0 eV.14 Figure 3a shows the I-V characteristics of the device obtained by sweeping a DC bias at a fixed location according to 0 V → 2 V → 0 V → -2 V → 0 V with a ramp rate of 0.2 V s-1. It is noted that device exhibits bipolar switching behaviour. It sets at positive bias and resets at a negative one. The I-V curve, presented in Figure 3a is separately analysed for different branches: at positive voltages, the current is low and increases nonlinearly (path #1) until the voltage reaches around +1.2 V from where the current increases suddenly and the corresponding voltage is identified as the ‘set’ voltage (Vset). Beyond 1.2 V, the current value reaches to a different state and fluctuates. On the other hand, during the decreasing cycle of voltage, current decreases linearly even for the negative bias, indicating the Ohmic nature between the device and contacts (path #2).10 A distinct change in resistance is also observed for both increasing and decreasing voltages, corresponding to a fixed bias of 0.5 V, which is known as high resistance state (HRS) and low resistance state (LRS), respectively. Subsequently, an opposite ‘reset’ process is also observed when sweeping the voltage from 0 to -2 V (Vreset, path #3), as is evidenced by a twostep switching from LRS to HRS [Figure 3a]. For more clarity of loop opening, Figure 3b shows the I–V curves in semi-log scale. The reproducibility of the result was tested by measuring the I– V characteristics for large number of cycles (Figure S1 in supporting information). Further, the reproducibility of the device fabrication was tested by performing the I-V measurements for four different devices (Figure S2 in supporting information).


Page 6 of 17

Page 7 of 17 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


The change in the current value at a fixed voltage (0.5V) across the device are also observed by applying different short voltage pulses (100 µs) during the measurement [Figure 3c]. In fact, the current across the device can be flipped for different values by applying various voltage pulses with a span of 100 µs. However, during all flipping the device does not return to its initial state and shows a small variation in the reset current.15 This is most likely due to a combined ionic-electronic movement across the device.8,16 This window of current variation for HRS can be considered as the 00 state (marked by grey colour in Figure 3c). In addition, another three current conduction states, at a fixed biased of 0.5 V, can also be achieved by applying short pulse of 2, 2.5, and 3 V, respectively. These three levels can be referred as 01, 10, and 11 states.15,17 The stability of the flipped state was also checked by measuring the current values for long time [Figure 3d]. These results confirm that the current across the device can be flipped at any higher state by choosing arbitrary voltage value. The transient behavior of the device was further investigated by applying voltage pulses and measuring resulting currents. Figure 3e shows the change in the current across the device, corresponding to different applied electric pulses. One can note that the current corresponding to the points (1) and (3) are the same while it is different for point (2), most likely due to the conducting filament formation due to applied +1.5 V. In addition, the figure, 3f depicts the current transient behavior for 10 cycles. Interestingly, the current value corresponding to +1.5 V increases for each pulse (marked by arrow), indicating that this device can be used for neuromorphic applications. Particularly, the possibility of gradual current change of the device emphasis us to apply it for neuromorphic computing. In fact, an analog memory device with the capability to tune the device current with pulse input signal is desired to realize the synaptic functionality. Therefore, we investigated the property of gradual current change in the context of pulse cycling. Generally,



neuron add the input signals and once the total reaches to the threshold, it generates spike signal. To confirm this finding, consecutive DC voltages pulses from 0 to +1.3 V were applied to the device, Figure 4a. The current level increase continuously after each pulse; this behavior is like the synaptic signal of biological synapses.18,19,20 In fact, the current can also be modulated by continually applying a programmed pulse. This fact is clearer when pulse with high frequency is applied to the device (last part of the Figure 4a), current increases more rapidly. This result confirms that the present transparent RS device is suitable for neuromorphic computing. The mechanism of the multimode RS and pulse-dependent gradual change in the current in a mixed electronic-ionic system are still under investigation, yet the possible reason behind the observed results may be the field-induced Br-ionic movement, which can generate the conducting filament formation.6,7,21 In fact, recently, Tian et al. demonstrated the presence of RS in 2D perovskite and based on Monte Carlo simulation, they have shown that isolated ionic Br vacancies migrate continuously and merge, which in turn form a conducting filament.12 Therefore, in the present device, the flipping of four current values can be attributed to the formation of different size of the filament, due to an increment in the ionic migration at relatively higher electric potential.21 In fact, the size of the filament can be tuned by ionic injection/extraction during the set process by changing applied electric field. In addition, the neuromorphic behaviour can also be attributed to the ionic movement. As the number of pulse increased, it pump more and more Br ions towards the one terminal and in turn increase the overall current.12 Further, the device shows linear current across the device in one state, which can be referred as a Ohmic-like device [Figure 4b]. These ions will reach to the perovskite-oxide interface and forms a potential barrier, which in turn shows a diode-like current conduction


Page 8 of 17

Page 9 of 17 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


[Figure 4c].16 In fact, the set and reset processes can be attributed to the electric field-induced ionic movement.21

4. CONCLUSIONS In conclusion, we have observed multilevel RS phenomenon in perovskite nanostructures. The high visible transmittance of the device has been confirmed. In addition, the device shows multileveled RS that be tuned well by choosing appropriate applied forming pulse. Moreover, the device shows voltage pulse-dependent gradual change in current, making it suitable for neuromorphic computing. The observed results are explained in terms of fieldinduced ionic migration and in turn improvement in the filament size. The results suggest that the optimization of the conductive filament active region is key for the future resistive switching devices. The present results will be a benchmark to design controlled resistive nanostructurebased memory devices.

AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected] (J.K.) and *E-mail: [email protected] (M. S. J.)

ACKNOWLEDGMENTS The authors acknowledge the financial support the Basic Science Research Program through the National Research Foundation (NRF) of Korea by the Ministry of Education (NRF2015R1D1A1A01059165). M.S.J. acknowledges support from the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (2016R1A2B2015581). Mohit Kumar and Hong-Sik Kim equally contributed to this work.



REFERENCES (1)

You, J.; Meng, L.; Song, T.-B.; Guo, T.-F.; Yang, Y. (Michael); Chang, W.-H.; Hong, Z.; Chen, H.; Zhou, H.; Chen, Q.; Liu, Y.; De Marco, N.; Yang, Y. Improved Air Stability of Perovskite Solar Cells via Solution-Processed Metal Oxide Transport Layers. Nat. Nanotechnol. 2015, 11 (1), 75–81.

(2)

Stoumpos, C. C.; Kanatzidis, M. G. Halide Perovskites: Poor Man’s High-Performance Semiconductors. Adv. Mater. 2016, 28, 5778–5793.

(3)

Choi, J.; Park, S.; Lee, J.; Hong, K.; Kim, D. H.; Moon, C. W.; Park, G. Do; Suh, J.; Hwang, J.; Kim, S. Y.; Jung, H. S.; Park, N. G.; Han, S.; Nam, K. T.; Jang, H. W. Organolead Halide Perovskites for Low Operating Voltage Multilevel Resistive Switching. Adv. Mater. 2016, 6562–6567.

(4)

Kwon, K. C.; Hong, K.; Van Le, Q.; Lee, S. Y.; Choi, J.; Kim, K. B.; Kim, S. Y.; Jang, H. W. Inhibition of Ion Migration for Reliable Operation of Organolead Halide PerovskiteBased Metal/Semiconductor/Metal Broadband Photodetectors. Adv. Funct. Mater. 2016, 26 (23), 4213–4222.

(5)

Hwang, B.; Lee, J.-S. Hybrid Organic-Inorganic Perovskite Memory with Long-Term Stability in Air. Sci. Rep. 2017, 7 (1), 673.

(6)

Liu, D.; Lin, Q.; Zang, Z.; Wang, M.; Wangyang, P.; Tang, X.; Zhou, M.; Hu, W. Flexible All-Inorganic Perovskite CsPbBr3 Nonvolatile Memory Device. ACS Appl. Mater. Interfaces 2017, 9 (7), 6171–6176.

(7)

Ercan, E.; Chen, J.; Tsai, P.; Lam, J.; Huang, S. C.; Chueh, C.; Chen, W. A Redox℃Based Resistive Switching Memory Device Consisting of Organic–Inorganic Hybrid Perovskite/Polymer Composite Thin Film. Adv. Electron. Mater. 2017, 1700344, 1–8.


Page 10 of 17

Page 11 of 17 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


(8)

Game, O. S.; Buchsbaum, G. J.; Zhou, Y.; Padture, N. P.; Kingon, A. I. Ions Matter: Description of the Anomalous Electronic Behavior in Methylammonium Lead Halide Perovskite Devices. Adv. Funct. Mater. 2017, 27 (16), 1606584.

(9)

Kim, D. J.; Tak, Y. J.; Kim, W. G.; Kim, J. K.; Kim, J. H.; Kim, H. J. Resistive Switching Properties through Iodine Migrations of a Hybrid Perovskite Insulating Layer. Adv. Mater. Interfaces 2017, 4 (6) 1601035.

(10)

Kumar, M.; Som, T. Structural Defect-Dependent Resistive Switching in Cu-O/Si Studied by Kelvin Probe Force Microscopy and Conductive Atomic Force Microscopy. Nanotechnology 2015, 26 (34), 345702.

(11)

Khurana, G.; Misra, P.; Katiyar, R. S. Multilevel Resistive Memory Switching in Graphene Sandwiched Organic Polymer Heterostructure. Carbon N. Y. 2014, 76, 341– 347.

(12)

Tian, H.; Zhao, L.; Wang, X.; Yeh, Y.-W.; Yao, N.; Rand, B. P.; Ren, T.-L. Extremely Low Operating Current Resistive Memory Based on Exfoliated 2D Perovskite Single Crystals for Neuromorphic Computing. ACS Nano 2017, 11, 12247–12256 acsnano.7b05726.

(13)

Yuan, M.; Quan, L. N.; Comin, R.; Walters, G.; Sabatini, R.; Voznyy, O.; Hoogland, S.; Zhao, Y.; Beauregard, E. M.; Kanjanaboos, P.; Lu, Z.; Kim, D. H.; Sargent, E. H. Perovskite Energy Funnels for Efficient Light-Emitting Diodes. Nat. Nanotechnol. 2016, 11 (10), 872–877.

(14)

Dou, L.; Wong, A. B.; Yu, Y.; Lai, M.; Kornienko, N.; Eaton, S. W.; Fu, A.; Bischak, C. G.; Ma, J.; Ding, T.; Ginsberg, N. S.; Wang, L.-W.; Alivisatos, A. P.; Yang, P. Atomically Thin Two-Dimensional Organic-Inorganic Hybrid Perovskites. Science (80-. ). 2015, 349



(6255), 1518–1521. (15)

Kim, Y.; Choi, H.; Park, H. S.; Kang, M. S.; Shin, K. Y.; Lee, S. S.; Park, J. H. Reliable Multistate Data Storage with Low Power Consumption by Selective Oxidation of Pyramid-Structured Resistive Memory. ACS Appl. Mater. Interfaces 2017, 9 (44), 38643– 38650.

(16)

Wu, Y.; Wei, Y.; Huang, Y.; Cao, F.; Yu, D.; Li, X.; Zeng, H. Capping CsPbBr3 with ZnO to Improve Performance and Stability of Perovskite Memristors. Nano Res. 2017, 10 (5), 1584–1594.

(17)

Nagareddy, V. K.; Barnes, M. D.; Zipoli, F.; Lai, K. T.; Alexeev, A. M.; Craciun, M. F.; Wright, C. D. Multilevel Ultrafast Flexible Nanoscale Nonvolatile Hybrid Graphene Oxide-Titanium Oxide Memories. ACS Nano 2017, 11 (3), 3010–3021.

(18)

Alibart, F.; Pieutin, S.; Guérin, D.; Novembre, C.; Lenfant, S.; Lmimouni, K.; Gamrat, C.; Vuillaume, D. An Organic Nanoparticle Transistor Behaving as a Biological Spiking Synapse. Adv. Funct. Mater. 2010, 20 (2), 330–337.

(19)

Pickett, M. D.; Medeiros-Ribeiro, G.; Williams, R. S. A Scalable Neuristor Built with Mott Memristors. Nat. Mater. 2013, 12 (2), 114–117.

(20)

Wang, Z.; Joshi, S.; Savel’ev, S. E.; Jiang, H.; Midya, R.; Lin, P.; Hu, M.; Ge, N.; Strachan, J. P.; Li, Z.; Wu, Q.; Barnell, M.; Li, G. L.; Xin, H. L.; Williams, R. S.; Xia, Q.; Yang, J. J. Memristors with Diffusive Dynamics as Synaptic Emulators for Neuromorphic Computing. Nat. Mater. 2017, 16 (1), 101–108.

(21)

Zhu, X.; Lee, J.; Lu, W. D. Iodine Vacancy Redistribution in Organic–Inorganic Halide Perovskite Films and Resistive Switching Effects. Adv. Mater. 2017, 29 (29), 1–8.


Page 12 of 17

Page 13 of 17 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


Figure 1 (a) Schematic of the transparent device, where PSC indicates the (C4H9NH3)2PbBr4, (b) Tilted-view SEM of the full device (c) Planar-view SEM of the (C4H9NH3)2PbBr4 thin film. (d) XRD spectra of (C4H9NH3)2PbBr4 thin film deposited on SiO2 substrate.



Figure 2. (a) Transmittance spectra of the device and the inset depicts the original photograph of the device. (b) Absorbance and photoluminance spectrum of (C4H9NH3)2PbBr4 on glass substrate.


Page 14 of 17

Page 15 of 17 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


Figure 3. (a) Two cycles current-voltage characteristics of the full device, whereas the semi-log behaviour of the same is depicted in (b). (c) Pulsed voltage-dependent flipping four different current states (yellow: 1 V, red: 2 V, blue: 2.5 V, magenta: 3 V) (d) Device stability in different states. (e) and (f) Transient behaviour of the device for one and 10 cycles, respectively.



Figure 4. (a) Pulse voltage-dependent change in the current, confirming its neuromorphic behaviour. (b) and (c) Schematic diagrams of the ionic movement and band bending, showing that the characteristics of the device can be change from resistive to diode-like due to ionic migration.


Page 16 of 17

Page 17 of 17 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


Table of Contents Graphic (TOC)


Compliance-Free Multileveled Resistive Switching in a Transparent

Recommend Documents