Photoresponse Enhancement in Monolayer ReS2 Phototransistor

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Photoresponse Enhancement in Monolayer ReS2 Phototransistor Decorated with CdSe-CdS-ZnS Quantum Dots Jing-Kai Qin, Dan-Dan Ren, Wen-Zhu Shao, Yang Li, Peng Miao, Zhao-Yuan Sun, PingAn Hu, Liang Zhen, and Cheng-Yan Xu ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b10349 • Publication Date (Web): 20 Oct 2017 Downloaded from http://pubs.acs.org on October 20, 2017

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Photoresponse Enhancement in Monolayer ReS2 Phototransistor Decorated with CdSe-CdS-ZnS Quantum Dots Jing-Kai Qin, †, ‡,¶,#Dan-Dan Ren, †,¶ ,# Wen-Zhu Shao, *,‡ Yang Li, ‡,¶ Peng Miao, § Zhao-Yuan Sun, ‡ PingAn Hu, ‡,¶ Liang Zhen, †,‡,¶ and Cheng-Yan Xu*,†,‡,¶ †

State Key Laboratory of Advanced Welding and Joining, Harbin Institute of

Technology, Harbin 150001, China. ‡

School of Materials Science and Engineering, Harbin Institute of Technology,

Harbin 150001, China. ¶

MOE Key Laboratory of Micro-Systems and Micro-Structures Manufacturing,

Harbin Institute of Technology, Harbin 150080, China §

School of Chemistry and Chemical Engineering, Harbin Institute of Technology,

Harbin 150001, China. #

These authors contributed equally to this work.

E-mail: [email protected]; [email protected] ABSTRACT ReS2 films is considered as a promising candidate for optoelectronic applications due to its direct bandgap character and optical/electrical anisotropy. However, the direct bandgap in a narrow spectrum and the low absorption of atomically thin flake weaken the prospect for light-harvesting applications. Here, we developed an efficient approach to enhance the performance of ReS2-based phototransistor by coupling

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CdSe-CdS-ZnS core-shell quantum dots. Under 589 nm laser irradiation, the responsivity of ReS2 phototransistor decorated with quantum dots could be enhanced by more than 25 times (up to ~654 A/W), and the rising and recovery time can be also reduced to 3.2 and 2.8 s, respectively. The excellent optoelectronic performance is originated from the coupling effect of quantum dots light absorber and cross-linker ligands 1,2-ethanedithiol. Photoexited electron-hole pairs in quantum dots can separate and transfer efficiently due to the type-II band alignment and charge exchange process at the interface. Our work shows that the simple hybrid 0D-2D hybrid system can be employed for photodetection applications. KEYWORDS: ReS2; exfoliation; quantum dots; 0D-2D hybrid system; photodetector 1. Introduction Transition metal dichalcogenides (TMDs) two-dimensional (2D) materials have attracted a great deal of attention in recent years. Their suitable bandgap ranging from 1–3 eV make them highly efficient in photoelectric conversion across a wide spectrum range.1-9 The major constraint of TMDs for the optoelectronic application is their limited photon absorption efficiency, which is determined by their ultra short absorption length (100 µm) after transfer due to the weak interlayer coupling effect of ReS2.29-30 Atomic force microscopy (AFM) was conducted to determine the thickness and surface topography. The typical thickness of monolayer ReS2 films is about 0.9 nm (Figure 2b), and the surface is atomic flat with roughness (Ra) of about 200 pm, almost equal to that of Si/SiO2 substrate (204 pm), suggesting a high quality of the films. Multilayer ReS2 films with different thicknesses ranging from 1.0 to 9.8 nm could also be obtained by this method. Figure S4 shows the optical microscopy image and AFM height profile of isolated multilayer ReS2 transferred onto Si/SiO2 substrate. Clearly, the monolayer samples could be easily identified by optical contrast. Raman spectrum collected from the monolayer sample is in agreement well with previous studies.31-32 Two dominant peaks are located at 151 and 213 cm-1, corresponding to in-plane Eg and out-of-plane Ag-like vibration modes (Figure S5). In addition, this exfoliation method could avoid the introduction of organic contaminations in traditional PMMA-assisted transfer process, which would degrade the contact quality of ReS2/QDs device. This procedure provides an alternative approach to obtain large-area ReS2 films for electronic applications. CdSe-CdS-ZnS core-shell QDs with high absorption efficiency are used as a model to investigate the charge transfer between ReS2 and QDs, since it has a stable emission peak that overlaps with ReS2 absorption features.33-34 According to the TEM image and size statistic histogram (Figure 2c), the size of the CdSe-CdS-ZnS QDs is estimated to be 5 ± 1.41 nm. The UV–vis–NIR absorption and PL spectra of

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CdSe-CdS-ZnS quantum dots are plotted in Figure 2d. The spectra are measured by dispersing QDs in toluene with a concentration of 1mg/mL. Typical exciton transition (1S(e)-1S 3/2 (h)) is detected at 2.04 eV, and PL emission exhibits a single peak at 1.98 eV, consistent with the previous studies.33

Figure 2e shows the optical

microscope image of QDs/ReS2 hybrid structure. QDs are distributed uniformly on the surface of ReS2 films, which was further demonstrated by AFM (Inset image of Figure 2e). UV–vis–NIR absorption spectrum of ReS2 films and hybrid structure are shown in Figure 2f. Compared with ReS2 films, the hybrid structure has an extra band edge absorption of 2.0 eV, indicating that QDs are successfully decorated on ReS2 films. In this work, EDT was used as cross-linker ligands to improve the contact quality between QDs and 2D ReS2 films.22, 26 As shown in Figure S6, the carrier and energy transfer at interface between QDs and ReS2 can not be well elucidated using traditional 3D semiconductor contact theory, since the thickness of monolayer ReS2 is much smaller than the depletion depth and transfer lengths.35 Due to the clean surface (no dangling bonds) of 2D ReS2, a van der Waals (vdW) gap would exist at the interface between QDs and ReS2. This gap could act as ‘tunnel barrier’ for carrier transfer, and greatly reduce the charge injection efficiency from QDs. In addition, the position of the bands in 2D ReS2 only changes laterally. Thus, the electrons form QDs would first inject into flat-band region A, and then diffuse to depletion region A’. Considering the above, the quality of interface contact between QDs and ReS2 would govern the carrier transfer behavior. EDT could tightly link the QDs and connect them with ReS2 films, and the effect of “tunnel barrier” induced by vdW gap would be

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largely minimized, thus the electrons could more easily transfer between QDs and ReS2. Field-effect transistor (FET) devices were fabricated based on monolayer ReS2 films, and the optoelectronic performance of device was tested before and after QDs deposition, as illustrated in Figure 3a. The source-drain current ( I ds ) modulation characteristic as a function of Vg of ReS2 device is presented in Figure 3b. It exhibits n-type transport behavior with a cut-off voltage of −27 V and ON/OFF ratio of 105. In the linear regime, we could calculate the carrier mobility of the device according to the following equation:

µ = Lg m / WCiVds

(1)

where gm represents transconductance, L is channel length (5 µm), W is channel width (10 µm) and Ci is the capacitance of SiO2. The carrier mobility ( µ ) is estimated to be 3.5 cm2 V-1 s-1 for ReS2 device. The QDs/ReS2 hybrid device does not show apparent depletion with the same Vg , and the carrier mobility increases to 9.8 cm2 V-1 s-1 by about three times at the cost of decreased Ion/Ioff ratio of 102. The improvement of n-type transport behavior is mainly attributed to the EDT passivation. Thiol molecules from EDT ligands could be tightly bound to sulphur vacancies in ReS2 films, which would cure the S vacancies and act as electron dopants to increase the carrier mobility.26 Besides, Fermi level of CdSe is located at higher position compared with ReS2, which means that electrons in conduction band (CB) of CdSe would flow into the ReS2 to form a built-in field until Fermi levels reach equilibrium, leading to the ReS2 more n-type doped. Under 589 nm laser irradiation, QDs/ReS2

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hybrid device exhibits a positive photoconductivity in the whole range of gate sweeping, similar with that in PbS/MoS2 hybrid system.22 Figure 3c illustrates the typical output curves of the device before and after QDs deposition. Photocurrent (Iph) of ReS2 phototransistor is only 5.5 nA, and it raises rapidly up to 140 nA after QDs deposition, which is almost 25 times larger. Here, Iph is defined as the difference between Ion and Ioff with source-drain voltage 3 V and gate voltage 0 V. Responsivity Rλ was calculated to better understand the role of QDs on device performance. The value of Rλ can be obtained using following formula:

Rλ = I ph / PS

(2)

where Iph the generated photocurrent, P is the incident power, and S is the effective illuminated area. Figure 3d plots the photocurrent and photoresponsivity evolution under different power density (0.12–20 mW/cm2, 589 nm). Both the photocurrent and responsivity are linearly proportional to the incident power, suggesting that the photoresponse of the hybrid device is mainly dominated by the amount of photogenerated carriers.26 The dotted lines for Iph and Rλ match well with the data using functions I ph = P β ( Rλ = P β −1 ). The constant ( β ) is calculated to be 0.77, which is much higher than that in SnS2-CIS and WS2-SnSe2 hybrid phototransistors.21, 36. The value of β reflects the photoelectric conversion efficiency, and it is related to a complex process including photon-generated electron-hole pairs generation, recombination, and trapping. Such high β in present work suggests the excellent photoresponse in ReS2/QDs hybrid system. The hybrid device shows dramatically high Rλ on the order of 102–103 A/W, with the maximum value up to

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654 A/W at power density of 0.12 mW/cm2, which is comparable with previously reported CuInSe2-SnS2 and graphene-MoS2 hybrid phototransistors.21, 37 Figure 3e shows the spectral output curves of the hybrid device. The highest photocurrent is obtained under 532 nm excitation. It should be noted that the hybrid phototransistor almost do not respond to laser with wavelength larger than 800 nm, since the energy of incident laser is outside the absorption spectrum of QDs. The results indicate that the photoresponse of QDs/ReS2 hybrid device was highly sensitive to the specific wavelength of illuminated laser. The wavelength depended photoresponsivity matches well with the absorption spectrum of QDs (Figure 3f), which means that the photoresponse of QDs/ReS2 hybrid device is determined by the absorption of QDs. Under illumination, the photoexcited electrons in QDs transport to conduction band of ReS2, leading to a considerable enhancement of photoconductance in the channel. The Rλ of QDs/ReS2 hybrid device is about two orders of magnitude higher than that of ReS2 device, as plotted in Figure 4a. Rλ decreases slightly with power increasing, with the lowest responsivity down to 105 A /W at P=20 mW/cm2. This is because more photoexcited electrons in QDs would be generated at higher illumination power, which would introduce a reverse electric filed and compensate the built-in electric field in space charge region, thus the responsivity would be reduced due to the acceleration of photoexcited electron-hole recombination.36 The time-depended photoresponse of device is illustrated in Figure 4b. Response time is defined as the time taken form dark current increasing to 63% of the maximum

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stable photocurrent, and recovery time is that taken decreased to 37% the maximum. The calculated response and recovery time of the hybrid device are 3.2 and 2.8 s, much faster than that of pristine ReS2 before decoration (12 and 13 s). It is worthy noted that both of the rising time and recovery time of ReS2 device are larger than that of few-layer ReS2 devices. The prominent reason for low response speed of 2D optoelectronic devices is trap states, which could capture and localize photoexcited carriers and increase their lifetime for recombination, causing a prolonged response time.12, 38 In our experiments, the ultrasonic-assisted exfoliation process would cause lots of defects in such large-area monolayer ReS2 films and introduce trap states in the band gap, leading to an slow response dynamics. As the rising and falling edge of ReS2 film photodetector shown in Figure S7, both of which consist of several fitted straight lines with different slopes, indicating the existence of various trap states in monolayer ReS2 films.39 The enhanced responsivity of QDs/ReS2 hybrid phototransistor could be explained by the type-II band alignment at interface as shown in Figure 5. It is worthy noted that the photoexcited carriers in CdSe cores could still be efficiently separated and transferred in spite of type-I band structure at shell/core interface.33 Consist with previous reports,26,

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the estimated conduction levels (valence levels) of the

monolayer ReS2 and CdSe QDs are –3.98 eV (–5.60 eV) and –3.53 eV (–5.21 eV), respectively (Figure S8). The conduction and valence levels of the QDs are both located at higher position compared to ReS2, which means that type II band alignment could be formed at the contact interface, and the electrons (holes) transfer between

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QDs and ReS2 would lead to a n-type doping of ReS2. Under illumination, large number of electron-hole pairs are photoexcited due to the high absorption efficiency of QDs, which are transported laterally through the channel driven by difference in conduction energy levels, leaving holes trapped in QDs.21, 26 Meantime, the built-in field in the heterojunction could prevent the fast recombination of photogenerated carriers in QDs. As long as the holes stay in QDs, the electrons could transfer into channel and generate gain.26 The increase of the carrier density of ReS2 leads to the considerable performance enhancement of QDs/ReS2 hybrid phototransistors. We also investigated the effect of EDT and QDs separately, as shown in Figure S9. In the presence of EDT, CH3S- groups in EDT could be tightly bound to sulphur vacancies in ReS2 via covalent binding (Figure S10a), which would cure these defects and build continuous transport channel for carriers.41 In addition, EDT could also act as passivation to protect the film surface from oxygen and moisture in ambient condition.26, 38 Thus, the photoexited electron-hole pairs could separate and transfer at the interface more efficiently under illumination, resulting in the reduction of response time. Meanwhile, the photoresponsivity also increases compared with the original sample due to the improved quality of ReS2 film, although EDT does not show any response to illumination. To eliminate the effect of EDT, CdSe-CdS-ZnS QDs were dissolved into methylbenzene, and then a few drops of QDs were casted on the surface of ReS2 films. Under illumination, considerable photoexited electrons in QDs could also transfer into ReS2 due to the high light absorption efficiency of QDs and large conduction band difference at QDs/ReS2 interface, leading to the

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enhancement of photoresponsivity. However, without EDT as cross-linker ligand, the QDs and ReS2 could not be connected efficiently and sulphur vacancies in ReS2 still exist, thus the response time of device does not show any improvement. It is worthy noted that QDs also contribute to the improved response speed. As shown in Figure S10b, the energy barrier created by the n–n interface between QDs and ReS2 contact would induce an anti-built in potential, which would significantly reduce the leakage current in channel and hinder the carrier transfer from QDs to ReS2 in the dark. Thus, the photoexited electrons in QDs conduction levels are rapidly recombined, resulting in the fast falling time26. The results indicate that the improvement of photoresponse is determined by the coupling effect of EDT treatment and QDs decoration. Conclusions In summary, we reported a feasible way to obtain large area monolayer ReS2 films using ultrasonic-assisted liquid exfoliation approach. By spin-coating CdSe-CdS-ZnS core-shell QDs, the responsivity of the ReS2-based photodetector could be improved about 25 times, reaching up to 654 A/W under 589 nm laser illumination with power identity of P=0.12 mW/cm2, and the response time of hybrid device is also reduced. The enhanced optoelectrical performance of hybrid phototransistor is originated from the coupling effect of EDT and QDs, where QDs could act as light absorber while EDT as cross-linker ligand at interface. The strategy described here could not only broaden the application of ReS2, but also provide an efficient method to improve the performance of photodetector based on other 2D materials, thus enabling novel applications for traditional photodetectors.

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ASSOCIATED CONTENT Supporting Information Available Experimental details about ultrasonic exfoliation and spin-coating process of QDs, optical microscopy image and AFM height profile, Raman spectra exfoliated ReS2, vacuum energy level of materials, contact junction and band diagrams, DFT calculation results, time resolved photoresponse of device, S-vacancy repairing mechanism diagram and anti-built potential at QDs/ReS2 interface. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]; [email protected] Notes The authors declare no competing financial interest.

Acknowledgments This work was financially supported by National Natural Science Foundation of China (No.51772064 and No. 51572057).

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Figures

Figure 1. Schematics of QDs/ReS2 hybrid structure and energy band alignment in QDs.

Figure 2. (a) Optical microscopy and (b) AFM tomography images of monolayer ReS2 films. Inset in (b) is its height profile. (c) TEM image of CdSe-CdS-ZnS core-shell QDs showing the uniform size distribution. Inset is the size statistic histogram. (d) PL and UV–vis–NIR spectra of CdSe-CdS-ZnS

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QDs. (e) Optical image of ReS2 films coated with CdSe-CdS-ZnS QDs. Inset shows the AFM image of uniformly distributed CdSe-CdS-ZnS QDs on ReS2 surface. (scale bar in AFM image) (f) UV-vis-NIR absorption spectra of the ReS2 films before and after QDs deposition.

Figure 3. (a) Schematic of QDs/ReS2 hybrid photodetector. (b) Transfer curves of the device with Vds=3V.(c) I–V curves of the device. Inset shows the optical image of ReS2 photodetector. Scale bar is 10 µm. (d) Photocurrent and responsivity as a function of incident power. (e) Output curves of the device under incident illumination with different wavelengths. (f) Responsivity characteristics as a function of illumination wavelength. 17

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Figure 4. (a) The dependence of the responsivity on the incident illumination power ( λ =589 nm, Vds=3V). (b) A separated response and reset cycle of hybrid devices ( λ =589 nm, Vds=1V, P=1.2 mW/cm2).

Figure 5. (a) Schematic diagram of a QDs/ReS2 hybrid system. (b) The band structure at the interface between ReS2 and QDs

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References (1) Bernardi, M.; Palummo, M.; Grossman, J. C. Extraordinary Sunlight Absorption and One Nanometer Thick Photovoltaics Using Two-dimensional Monolayer Materials. Nano Lett. 2013, 13 (8), 3664-3670. (2) Das, S.; Chen, H.-Y.; Penumatcha, A. V.; Appenzeller, J. High Performance Multilayer MoS2 Transistors with Scandium Contacts. Nano Lett. 2012, 13 (1), 100-105. (3) Eda, G.; Maier, S. A. Two-dimensional Crystals: Managing Light for Optoelectronics. ACS nano. 2013, 7 (7), 5660-5665. (4) Ganatra, R.; Zhang, Q. Few-layer MoS2: A Promising Layered Semiconductor. ACS nano. 2014, 8 (5), 4074-4099. (5) Hafeez, M.; Gan, L.; Li, H.; Ma, Y.; Zhai, T. Large‐Area Bilayer ReS2 Film/Multilayer ReS2 Flakes Synthesized by Chemical Vapor Deposition for High Performance Photodetectors. Adv. Funct. Mater. 2016, 26 (25), 4551-4560. (6) Lee, G.-H.; Yu, Y.-J.; Cui, X.; Petrone, N.; Lee, C.-H.; Choi, M. S.; Lee, D.-Y.; Lee, C.; Yoo, W. J.; Watanabe, K. Flexible and Transparent MoS2 Field-Effect Transistors on Hexagonal Boron Nitride-Graphene Heterostructures. ACS nano. 2013, 7 (9), 7931-7936. (7) Liu, F.; Zheng, S.; He, X.; Chaturvedi, A.; He, J.; Chow, W. L.; Mion, T. R.; Wang, X.; Zhou, J.; Fu, Q. Highly Sensitive Detection of Polarized Light Using Anisotropic 2D ReS2. Adv. Funct. Mater. 2016, 26 (8), 1169-1177. (8) Liu, N.; Tian, H.; Schwartz, G.; Tok, J. B.-H.; Ren, T.-L.; Bao, Z. Large-Area, Transparent, and Flexible Infrared Photodetector Fabricated Using PN Junctions Formed by N-Doping Chemical Vapor Deposition Grown Graphene. Nano Lett. 2014, 14 (7), 3702-3708. (9) Mak, K. F.; Lee, C.; Hone, J.; Shan, J.; Heinz, T. F. Atomically Thin MoS2: A New Direct-Gap Semiconductor. Phys. Rev. Lett. 2010, 105 (13), 136805. (10) Splendiani, A.; Sun, L.; Zhang, Y.; Li, T.; Kim, J.; Chim, C.-Y.; Galli, G.; Wang, F. Emerging Photoluminescence in Monolayer MoS2. Nano Lett. 2010, 10 (4), 1271-1275. (11) Wang, Q. H.; Kalantar-Zadeh, K.; Kis, A.; Coleman, J. N.; Strano, M. S. Electronics and Optoelectronics of Two-Dimensional Transition Metal Dichalcogenides. Nat. Nanotechnol. 2012, 7 (11), 699-712. (12) Yin, Z.; Li, H.; Li, H.; Jiang, L.; Shi, Y.; Sun, Y.; Lu, G.; Zhang, Q.; Chen, X.; Zhang, H. Single-Layer MoS2 Phototransistors. ACS nano. 2011, 6 (1), 74-80. (13) Zhang, W.; Chiu, M.-H.; Chen, C.-H.; Chen, W.; Li, L.-J.; Wee, A. T. S. Role of Metal Contacts in High-Performance Phototransistors Based on WSe2 Monolayers. ACS nano. 2014, 8(8), 8653-8661. (14) Zhou, Y.; Nie, Y.; Liu, Y.; Yan, K.; Hong, J.; Jin, C.; Zhou, Y.; Yin, J.; Liu, Z.; Peng, H. Epitaxy and Photoresponse of Two-Dimensional GaSe Crystals on Flexible Transparent Mica Sheets. ACS Nano, 2014, 8 (2), 1485–1490 (15) Koppens, F.; Mueller, T.; Avouris, P.; Ferrari, A.; Vitiello, M.; Polini, M. Photodetectors Based on Graphene, Other Two-Dimensional Materials and Hybrid Systems. Nat. Nanotechnol. 2014, 9 (10), 780-793. (16) Murphy, J. E.; Beard, M. C.; Norman, A. G.; Ahrenkiel, S. P.; Johnson, J. C. PbTe Colloidal

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Nanocrystals: Synthesis, Characterization, and Multiple Exciton Generation. J. Am. Chem. Soc. 2006, 128 (10), 3241-3247. (17) Tretiak, S.; Piryatinski, A. Modeling Photoexcited Carrier Interactions in Semiconductor Nanostructures. Nano Lett. 2005, 5 (5), 865-871. (18) Chen, Z.; Berciaud, S.; Nuckolls, C.; Heinz, T. F.; Brus, L. E. Energy Transfer from Individual Semiconductor Nanocrystals to Graphene. ACS nano. 2010, 4 (5), 2964-2968. (19) Yu, Y.; Zhang, Y.; Song, X.; Zhang, H.; Cao, M.; Che, Y.; Dai, H.; Yang, J.; Zhang, H.; Yao, J. PbS-Decorated WS2 Phototransistors with Fast Response. ACS Photonics. 2017, 4 (4), 950-956. (20) Yu, Y.; Zhang, Y.; Zhang, Z.; Zhang, H.; Song, X.; Cao, M.; Che, Y.; Dai, H.; Yang, J.; Wang, J. Broadband Phototransistor Based on CH3NH3PbI3 Perovskite and PbSe Quantum Dot Heterojunction. J. Phys. Chem. Lett. 2017, 8 (2), 445-451. (21) Huang, Y.; Zhan, X.; Xu, K.; Yin, L.; Cheng, Z.; Jiang, C.; Wang, Z.; He, J. Highly Sensitive Photodetectors Based on Hybrid 2D-0D SnS2-Copper Indium Sulfide Quantum Dots. Appl. Phys. Lett. 2016, 108 (1), 013101. (22) Kufer, D.; Nikitskiy, I.; Lasanta, T.; Navickaite, G.; Koppens, F. H.; Konstantatos, G. Hybrid 2D–0D MoS2–PbS Quantum Dot Photodetectors. Adv. Mater. 2015, 27 (1), 176-180. (23) Prins, F.; Goodman, A. J.; Tisdale, W. A. Reduced Dielectric Screening and Enhanced Energy Transfer in Single-and Few-Layer MoS2. Nano lett. 2014, 14 (11), 6087-6091. (24) Prasai, D.; Klots, A. R.; Newaz, A.; Niezgoda, J. S.; Orfield, N. J.; Escobar, C. A.; Wynn, A.; Efimov, A.; Jennings, G. K.; Rosenthal, S. J. Electrical Control of Near-Field Energy Transfer between Quantum Dots and Two-dimensional Semiconductors. Nano lett. 2015, 15 (7), 4374-4380. (25) Jasieniak, J. J.; Fortunati, I.; Gardin, S.; Signorini, R.; Bozio, R.; Martucci, A.; Mulvaney, P. Highly Efficient Amplified Stimulated Emission from CdSe‐CdS‐ZnS Quantum Dot Doped Waveguides with Two‐Photon Infrared Optical Pumping. Adv. Mater. 2008, 20 (1), 69-73. (26) Ra, H.-S.; Kwak, D.-H.; Lee, J.-S. A Hybrid MoS2 Nanosheet–CdSe Nanocrystal Phototransistor with a Fast Photoresponse. Nanoscale. 2016, 8 (39), 17223-17230. (27) Lee, Y.-L.; Chi, C.-F.; Liau, S.-Y. CdS/CdSe Co-Sensitized TiO2 Photoelectrode for Efficient Hydrogen Generation in a Photoelectrochemical Cell. Chem. Mater. 2009, 22 (3), 922-927. (28) Peng, X.; Schlamp, M. C.; Kadavanich, A. V.; Alivisatos, A. P. Epitaxial Growth of Highly Luminescent CdSe/CdS Core/Shell Nanocrystals with Photostability and Electronic Accessibility. J. Am. Chem. Soc. 1997, 119 (30), 7019-7029. (29) He, X.; Liu, F.; Hu, P.; Fu, W.; Wang, X.; Zeng, Q.; Zhao, W.; Liu, Z. Chemical Vapor Deposition of High‐Quality and Atomically Layered ReS2. Small. 2015, 11 (40), 5423-5429. (30) Keyshar, K.; Gong, Y.; Ye, G.; Brunetto, G.; Zhou, W.; Cole, D. P.; Hackenberg, K.; He, Y.; Machado, L.; Kabbani, M. Chemical Vapor Deposition of Monolayer Rhenium Disulfide (ReS2). Adv. Mater. 2015, 27 (31), 4640-4648. (31) Fujita, T.; Ito, Y.; Tan, Y.; Yamaguchi, H.; Hojo, D.; Hirata, A.; Voiry, D.; Chhowalla, M.; Chen, M. Chemically Exfoliated ReS2 Nanosheets. Nanoscale. 2014, 6 (21), 12458-12462. (32) Cui, F.; Wang, C.; Li, X.; Wang, G.; Liu, K.; Yang, Z.; Feng, Q.; Liang, X.; Zhang, Z.; Liu, S. Tellurium‐Assisted Epitaxial Growth of Large‐Area, Highly Crystalline ReS2 Atomic Layers on Mica Substrate. Adv. Mater. 2016, 28 (25), 5019-5024. (33) Jones, M.; Lo, S. S.; Scholes, G. D. Quantitative Modeling of The Role of Surface Traps in CdSe/CdS/ZnS Nanocrystal Photoluminescence Decay Dynamics. Proc. Natl. Acad. Sci. 2009,

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106 (9), 3011-3016. (34) Gooding, A. K.; Gómez, D. E.; Mulvaney, P. The Effects of Electron and Hole Injection on The Photoluminescence of CdSe/CdS/ZnS Nanocrystal Monolayers. ACS nano. 2008, 2 (4), 669-676. (35) Allain, A.; Kang, J.; Banerjee, K.; Kis, A. Electrical Contacts to Two-DimensionalSemiconductors. Nat. Mater. 2015, 14 (12), 1195. (36) Jia, Z.; Xiang, J.; Wen, F.; Yang, R.; Hao, C.; Liu, Z. Enhanced Photoresponse of SnSe-Nanocrystals-Decorated WS2 Monolayer Phototransistor. ACS Appl. Mater. Interfaces. 2016, 8 (7), 4781-4788. (37) Chen, C.; Qiao, H.; Lin, S.; Luk, C. M.; Liu, Y.; Xu, Z.; Song, J.; Xue, Y.; Li, D.; Yuan, J. Highly Responsive MoS2 Photodetectors Enhanced by Graphene Quantum Dots. Sci. Rep. 2015, 5, 11830. (38) Zhou, J.; Gu, Y.; Hu, Y.; Mai, W.; Yeh, P.-H.; Bao, G.; Sood, A. K.; Polla, D. L.; Wang, Z. L. Gigantic Enhancement in Response and Reset Time of ZnO UV Nanosensor by Utilizing Schottky Contact and Surface Functionalization. Appl. Phys. Lett. 2009, 94 (19), 191103. (39) Jiang, Y.; Zhang, W. J.; Jie, J. S.; Meng, X. M.; Fan, X.; Lee, S. T. Photoresponse Properties of CdSe Single‐Nanoribbon Photodetectors. Adv. Funct. Mater. 2007, 17 (11), 1795-1800. (40) Liu, H.; Xu, B.; Liu, J.-M.; Yin, J.; Miao, F.; Duan, C.-G.; Wan, X. Highly Efficient and Ultrastable Visible-Light Photocatalytic Water Splitting over ReS2. Phys. Chem. Chem. Phys. 2016, 18 (21), 14222-14227. (41) Li, Q.; Zhao, Y.; Ling, C.; Yuan, S.; Chen, Q.; Wang, J. Towards a Comprehensive Understanding of The Reaction Mechanisms Between Defective MoS2 and Thiol Molecules. Angew.Chem. Int. Ed. 2017, 56,10501 –10505

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