Efficient Charge Transfer in Narrowband Organic Photodiodes Based on Self-Assembled Heterojunction for Spectrally Selective Photodetection and Imaging

摘要

Spectrally selective photodetection has been used in many areas where onlyband-specific optical signals are aimed to be detected. Organic photodiodes(OPDs) based on internal light depletion mechanisms have been utilized torealize narrowband photodetection. However, the fabrication of thephotoactive layers by conventional solution methods can result in thedeterioration of the underneath organic depletion layers and causehigh-density defect states at their interface. Herein, a new approach ispresented to realize efficient charge transfer by adopting a self-assemblystrategy to prepare donor/acceptor bulk heterojunctions as the photoactivelayers for narrowband OPDs. This method is able to prepare highly smooth,phase-uniform, and low-defect-density thin films with controlled thickness.With this strategy, a narrowband near-infrared OPD centered at 760 nm with afull-width-at-half-maximum of around 60 nm, peak external quantumefficiency of 49, and peak specific detectivity of over 10~（13） Jones under ?5 Vis achieved. Multiple material combinations for the depletion and photoactivelayers are examined, and the results show the effectiveness to realize thespectrally selective photodetection (from 740 to 900 nm) in general. Moreimportantly, the narrowband OPDs can be integrated into a matrix forimaging, which demonstrates the mass-scale fabrication feasibility of theseOPDs.