Solution-Processed Uniform MoSe₂–WSe₂ Heterojunction Thin Film on Silicon Substrate for Superior and Tunable Photodetection

Abstract

2-D transition metal dichalcogenide (TMDC)-based heterostructures are promising active materials for high-performance optoelectronic devices. The low-cost, large-area, and high-quality fabrication of TMDC heterojunctions is essential for the efficient output of the device. Here, we demonstrate thin films of MoSe2–WSe2 nanocrystals deposited on a silicon substrate for enhanced photodetection. A MoSe2–WSe2 film, deposited by the electrophoretic deposition method, is initially transferred on the water surface and then prudently transferred on the p-Si (100) substrate. Scanning electron microscopy reveals the continuous and compact distribution of assembled nanocrystals with no pinhole. Energy-dispersive analysis of X-ray confirms the presence of MoSe2 and WSe2 in the transferred heterojunction film. The MoSe2–WSe2/p-Si fabricated heterojunction achieves a peak responsivity and external quantum efficiency of 336 mAW–1 and 80% (520 nm, 0.122 mW/cm2), respectively, which are ∼4 times higher in magnitude than those of pristine TMDC/Si fabricated heterojunctions. The enhanced photoresponse behavior is attributed to the superior absorbance in the visible region and type-II band alignment between MoSe2 and WSe2 nanocrystals, which facilitates improved generation and separation of charge carriers. Further, the photoresponse of MoSe2–WSe2/Si heterojunction is recorded in the temperature range of 45–300 K. The excellent heterojunction characteristic and photoresponse behavior of liquid exfoliated TMDC nanocrystals are the future gateways of highly efficient hybrid optoelectronic devices.

Flexible Self‐Powered Electrochemical Photodetector Functionalized by Multilayered Tantalum Diselenide Nanocrystals

“…Figure S2b The P ph gradually increases with the increase in applied bias potential from 0 to 0.6 V. The bias potential increases the separation rate of photoinduced electron-hole pairs by increasing their drift velocity and reduces the recombination rate, resulting in the increased photocurrent density. [17] Transient photoresponse of TaSe 2 NCs at the bias potential of 0.6 and 0.3 V in different electrolytes as a function of different illumination intensities is shown in Figure 5b and Figure S3a,b (Supporting Information). Even at higher biasing conditions, the P ph follows the same trend of 0.5 KOH > 0.2 KOH > 0.5 NaOH > 0.5 Na 2 SO 4 .…”

“…[14][15][16] The layer dependent electrical and optical characteristics of TMDCs opened up a new pathway for the development of simple functioning nanoelectronic, lightweight, and flexible devices. [17,18] TMDCs materials exhibit high chemical stability in ambient conditions for electrochemical systems in comparison to other 2D materials such as black phosphorus (BP) with high light-induced fast degradation. [19,20] Metallic TMDCs, on the other hand, are a less studied class of materials due to their metallic nature and two-stage transition.…”

Graphdiyne Visible‐Light Photodetector with Ultrafast Detectivity

“…To date, the majority of research projects involving a visible light response predominantly focus on quantum dots, [ 2 ] inorganic nano‐films, [ 3 ] organic perovskites, [ 4 ] and transition‐metal dihalides. [ 5 ] In terms of applications convenience, those photodetector components are either limited by the device construction technology or by the slow response speed and relatively narrow detection range. [ 6 ] For instance, ultra‐fast photoresponse characteristics usually demand the construction of heterojunctions through chemical vapor deposition or mechanical exfoliation methods, which always necessitates thorough consideration of the lattice matching, thus rendering the production process much more complex.…”

“…[ 6 ] For instance, ultra‐fast photoresponse characteristics usually demand the construction of heterojunctions through chemical vapor deposition or mechanical exfoliation methods, which always necessitates thorough consideration of the lattice matching, thus rendering the production process much more complex. [ 5 ] In the process of obtaining convenient and high‐performance photoelectric devices, 2D materials represented by graphene or black phosphorus have increasingly become the center of attention due to their broadband light absorption, high response speed, and ultra‐high carrier mobility. [ 7 ] However, the relatively low range of visible light absorption and fast hole–electron recombination rate in graphene result in a high dark current, which suppresses the photodetection sensitivity.…”

MXene/Graphene Oxide Heterojunction as a Saturable Absorber for Passively Q-Switched Solid-State Pulse Lasers

“…For example, solar cells using 2-D heterojunctions have been reported, obtaining better absorption coefficients and excellent stability [ 22 , 23 , 24 , 25 ]. In addition, mid-infrared detectors employing 2-D heterojunctions were also reported to achieve excellent performance due to the optimum structure of heterojunctions [ 26 , 27 , 28 ]. However, the preparation conditions of such 2-D heterojunctions were strict, and their application mechanism has not been clarified.…”