Efficient organic self-powered photoelectrochemical photodetectors based on conjugated polymers/fullerene heterojunctions

Abstract

A new class of all-organic self-powered photoelectrochemical photodetectors (OPEC PDs) based on PDTBT-Qx/PC₇₁BM were successfully constructed and the performance of PDTBT-Qx/PC₇₁BM OPEC PDs was systematically evaluated. The synthesized copolymer PDTBT-Qx exhibited two dominant absorption peaks at around 370 nm and 700 nm and excellent thermal stability. Moreover, the energy level of PDTBT-Qx matches well with that of PC₇₁BM, meaning good compatibility with PC₇₁BM. Therefore, we applied PDTBT-Qx/PC₇₁BM blend films as photoanode layers to fabricate a new class of OPEC PDs with a configuration of FTO/PDTBT-Qx/PC₇₁BM/electrolyte/Pt/FTO. Compared with the photodetectors based on pure PC₇₁BM films, the PDTBT-Qx/PC₇₁BM OPEC PDs exhibited good UV-visible photoresponse with large responsivity (16.36 mA W⁻¹ at 365 nm and 19.25 mA W⁻¹ at 620 nm) and fast response speed (τ_r/τ_d values are 15 ms/20 ms at 365 nm and 20 ms/31 ms at 620 nm) without bias due to strong absorption of PDTBT-Qx and the increment of exciton dissociation efficiency at the interface between PDTBT-Qx and PC₇₁BM. Additionally, the PDTBT-Qx/PC₇₁BM OPEC PDs do not require a harsh preparation environment, and all the fabrication processes are conducted in air. All the results indicate the excellent self-powered photodetection ability of PDTBT-Qx/PC₇₁BM OPEC PDs, suggesting a promising configuration in the field of optoelectronic applications.