Helical polyisocyanides with thermally activated delayed fluorescence pendants for efficient circularly polarized light emission and detection

Abstract

Chiral organic polymeric semiconductors are widely regarded as promising candidates for circularly polarized light (CPL) detection due to their advantages of easy chemical modification, solution processing and low cost. However, traditional organic polymeric materials face low photoresponsivity and photocurrent asymmetry factor when constructing CPL detectors. To address this issue, we develope single-handed helical polyisocyanides with thermally activated delayed fluorescence (TADF) feature to fabricate a donor-acceptor heterojunction photodetector with C₆₀, where efficient triplet exciton utilization enables a high photocurrent response while the static single-handed helical main chains of polyisocyanides ensure a high photocurrent asymmetry factor, simultaneously. Furthermore, the performance of TADF polyisocyanides is conveniencely optimized by copolymerizing the host. Benefiting from the comprehensive functionality of TADF polyisocyanides, the prepared photodetectors exhibit a high responsivity of 0.21 A W⁻¹ and a very high photocurrent asymmetry factor of up to 0.12, which make it superior to the reported CPL photodetectors based on organic polymers. In addition, the detector has excellent reproducibility enabling no photocurrent roll-off after 1000 cycles. The long-term stability in ambient air also manifests its robustness. This work paves a new way for high-efficiency polymers based CPL detectors.