Effectively Enhanced Broadband Phototransistors Based on Multilayer WSe2/Pentacene

Abstract Broadband photodetectors sensitive to light from visible to near‐infrared are essential for various applications such as thermal evaluation, bio‐imaging mapping, and bio‐health monitoring. Multilayer WSe 2 offers broad light spectral responses and roles in broadband phototransistors’ active matrix. However, it shows relatively lower photoresponsivity than monolayer WSe 2 due to layer‐dependent energy band variations. Pentacene islands, a p‐type organic material, are formed on the multilayer WSe 2 to enhance its photoresponsivity under broadband lights. Pentacene islands can prominently absorb ultra‐violet to visible lights and generate enormous excitons. Besides, they have relatively long exciton diffusion lengths in micrometer scales to effectively enable exciton migration and charge transfer at the pentacene and WSe 2 interface. Consequently, the photocurrent ( I ph ) and the photoresponsivity ( R ph ) in WSe 2 /pentacene transistors are 1.41 µA and 19.313 A W −1 for 638‐nm light and 0.20 µA and 1.16 A W −1 for 852‐nm light. Therefore, WSe 2 /pentacene‐based phototransistors can be applied for broadband photodetectors under visible to near‐infrared.