Spectral Selective and Low-Noise Thin-Film Organic Photodetectors Enabled by Electric-Field Engineering.

Abstract

Spectral selective response is a key advantage of organic photodetectors for next-generation imaging and sensing systems. However, under some practical operating conditions, organic photodetectors are typically subjected to high dark current that limits the device detectivity. Here, we report an electric-field-engineering strategy that enables tunable spatial carrier extraction in donor-acceptor bulk heterojunctions through doping-induced space-charge redistribution. By reshaping the internal electric-field profile, the carrier-extraction region can be selectively tuned across the active layer. Therefore, the engineered field profile suppresses extraction of injected carriers, contributing to low dark current and high detectivities under reverse bias. Simultaneously, spatial selective extraction of photocarriers enables tuning of the photoresponse bandwidth of thin-film organic photodetectors without external optical filters. The spectral response can be systematically tuned across multiple material systems, dopants, and device architectures. These results establish electric-field engineering as a general framework for spectrally selective, high-detectivity organic photodetection under practically relevant operating conditions.