Large-Scale Solution-Processed Ultrathin 2D Tri-layer Heterostructures for Photodetector Applications

Heterojunction-based photodetectors of 2D TMDs provide the solution-processability and scalability to fabricate devices. In this study, we have produced photodetectors using a solution-processable approach, focusing on the heterojunction of 2D transition metal dichalcogenides (TMDs). The photodetection properties of the fabricated devices have been thoroughly examined at two different wavelengths 660 nm and 785 nm. This hybrid 2D tri-layer heterojunction strategy, employing a MoS2/MoSe2 heterojunction as the photosensitizer and a TiS2 layer as the conducting pathway, is fabricated to understand high-performance photodetectors. A simple and low-cost solution process was used to fabricate all the active layers of the photodetector. 2D TMDs were synthesized by liquid phase exfoliation which exhibits absorption in both visible as well as NIR spectral regions. The as-fabricated photodetector shows a response time of 220 msec and responsivity of similar to 28 mA W-1 in the visible region and similar to 44 mA W-1 in the near IR region. This improved response of the as-fabricated photodetector of tri-layer heterojunction results from the effective decrease in recombination rate and efficient electron-hole separation.