Novel Polymer Donors Based on Strong Electron-Withdrawing Unit and Non-Covalent Interactions for Ultra-Sensitive Near-Infrared Organic Photodetectors in Health Monitoring

Near-infrared (NIR) organic photodetectors (OPDs) have many important potential applications, while their detection performance is limited by high dark current density (J_d) and low responsivity (R), which are closely related to the lack of systematic studies on polymer donors. Herein, two novel polymer donors, named PBPyT-EH and PBPyT-BO, are demonstrated with strong electron-withdrawing units. Among them, PBPyT-EH exhibits superior morphology and charge characteristics owing to the subtle regulation of non-covalent interactions. Consequently, an impressively high R of 0.54 A W⁻¹ and suppressed J_d of 1.88 × 10⁻⁹ A cm⁻² at −1 V can be achieved, leading to a remarkable specific detectivity of 2.20 × 10¹³ Jones at −1 V and over 10¹⁴ Jones in self-powered mode (0 V), representing one of the highest detection performances. Meanwhile, the pulse signals can be clearly monitored based on the optimized device. This work illustrates the viability of PBPyT-polymer donors and offers a promising pathway for the practical application of sensitive NIR OPDs in health monitoring.