Thermally Robust Organic Photodetectors Enabled by Polymer Acceptors with Tunable Rigidity

Organic photodetectors (OPDs) have emerged as promising candidates for next-generation optoelectronic applications. However, their widespread adoption is hindered by the low thermal stability. This study addresses this issue by investigating the performance of OPDs employing three polymer acceptors: PF5-Y5, PYTS-C2, and PY2TS-C2 paired with the PBDB-T polymer donor. These devices demonstrate significantly improved resistance to thermal stress. After annealing at 150 °C for 1 h, the PF5-Y5-based OPDs can maintain a dark current density (Jd) below 1 × 10–6 A/cm2 and an external quantum efficiency (EQE) above 50%, leading to a specific detectivity of 1.7 × 1011 Jones. Detailed analysis reveals that the EQE drop in the PF5-Y5-based OPDs is due to decreased electron mobility, and Jd increases in the PY2TS-C2 and Y6 systems are attributed to enhanced aggregation and phase separation and C60 and electrode diffusion. These results highlight the advantages of polymer acceptors in enhancing thermal robustness and provide design strategies for developing thermally stable OPDs.