Improved Dual‐Polarity Response via Pyro‐phototronic Effect for Filterless Visible Light Communication

Abstract

AbstractDual‐polarity response photodetectors (PDs) take full advantage of the directivity of the photocurrent to identify optical information. The dual‐polarity signal ratio, a key parameter that represents the equilibrium degree of responses to different lights, is proposed for the first time. The synchronous enhancement of dual‐polarity photocurrents and the amelioration of the dual‐polarity signal ratio are beneficial to the practical applications. Herein, based on the selective light absorption and energy band structure design, a self‐powered CdS/PEDOT:PSS/Au heterojunction PD consisting of a p‐n junction and a Schottky junction exhibits unique wavelength‐dependent dual‐polarity response, where the photocurrent is negative and positive in the short and long wavelength regions, respectively. More importantly, the pyro‐phototronic effect inside the CdS layer significantly improves the dual‐polarity photocurrents with the maximum enhancement factors of 120%, 343%, 1167%, 1577%, and 1896% at 405, 450, 532, 650, and 808 nm, respectively. Furthermore, the dual‐polarity signal ratio tends to 1:1 due to different degrees of the enhancement. This work provides a novel design strategy for dual‐polarity response PDs with a simple working principle and improved performance, which can supply a substitution for two traditional PDs in the filterless visible light communication (VLC) system.