Ultrathin, Transparent, Flexible, and Self-Powered Photodetector Based on Two-Dimensional Materials and Self-Assembled Polar-Monolayer

Abstract

Flexibility, transparency and self-powered operation are three desirable features for the practical application of advanced photodetectors. In this work, an ultrathin, flexible, self-powered, and transparent photodetector made from all two-dimensional (2D) materials with polar monolayer is proposed and demonstrated. This device consists of a layer of graphene serving as a transparent electrode, a single-layer tungsten disulfide (WS2) acting as a light-absorbing layer, a self-assembled monolayer (SAM) of P3HT-COOH with polar property to provide an additional built-in electric field, and an indium-tin-oxide (ITO) coated polyethylene terephthalate (PET) flexible substrate. The average transmittance in the visible light regime is around 67%. Under zero bias voltage, the photodetector exhibits a responsivity of 1.58 mA∙W-1 and a detectivity of 3.29 × 109 Jones. Additionally, this flexible photodetector demonstrates good retention, retaining its original responsivity magnitude after 150 bending cycles without too much significant change. Based on the aforementioned properties, this ultrathin, transparent, flexible, and self-powered photodetector based on all 2D materials with polar monolayer offers an attractive option for developing advanced optoelectronic technologies.