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

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/cm(2)), respectively, which are similar to 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 MoSe 2 -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.