A homogenous polymer design with widely tunable work functions for high-performance two-dimensional photodetectors

Contact electrodes, which significantly influence the Schottky barrier and interfacial quality with two-dimensional (2D) materials, are key to boosting the performance of 2D photodetectors. However, it is challenging to fabricate electrically conducting films with sufficiently high or low work functions in homogenous electrodes for 2D devices due to the fixed work function of traditional metallic and semi-metallic electrodes, which restricts their adaptability for 2D metal-semiconductor-metal (MSM) structured photodetectors. Here, we utilize a homogenous PEDOT:PSS electrode designed with adjustable work function ranging from 5.1 to 3.2 eV in 2D MSM photodetectors, achieving a high rectification ratio of ~105 and superior performance metrics: responsivity up to 1.8 A W-1, an Ilight/Idark of 108, and an ultrafast response time of 3.2 μs. Meanwhile, the excellent transparency of PEDOT:PSS electrode extends the 2D device's response to the near-infrared (NIR) region, overcoming the semiconductor bandgap limitation. The universality of polymer electrode is proven across various 2D photodetectors, and its flexibility enables the creation of durable, wearable 2D devices. This work paves the way for the development of flexible, self-powered photodetectors, heralding a new era of next-generation intelligent interactive systems.