Dual Interfacial Layer Modulated Tunneling Mode for Low Dark Current Bidirectional Photomultiplication All-Polymer Photodetectors

Abstract

All-polymer photomultiplication photodetectors have attracted wide interest due to their flexibility and solution processability. However, the high bias required to achieve gain and high dark current density (J_d) continue to constrain their practical applications. In this work, we report low-bias, high-gain photomultiplication all-polymer photodetectors. Specifically, a low donor:acceptor ratio of 1:100 effectively suppresses leakage current and reduces J_d, while still enabling efficient photocurrent gain. By regulating interfacial carrier transport via a dual-hole-blocking layer (d-HBL), the tunneling behavior is effectively modulated, enabling suppressed J_d while maintaining high photomultiplication gain. Devices based on BCP/PFN-Br exhibit J_d as low as 1.74 × 10^–6 A cm^–2 at −5 V bias. The BCP/PFN-Br device, in particular, achieves an external quantum efficiency (EQE) of 5953% and a measured-noise-based specific detectivity (D*) of 1.95 × 10¹⁰ Jones under −5 V bias at a wavelength of 860 nm. While the PFN-Br single-HBL(s-HBL) exhibits higher LDR and D*, the BCP/PFN-Br d-HBL provides stronger J_d suppression and more effective regulation of interfacial carrier tunneling, highlighting a trade-off between the s-HBL and d-HBL configurations. This work demonstrates an effective interfacial strategy for regulating carrier transport in photomultiplication photodetectors, enabling dark-current suppression while maintaining high photomultiplication gain for weak-light sensing applications.