Suppressing Noise and Leakage Current in PbS Quantum-Dot Short-Wave Infrared Photodiodes via a PM6 Conjugated Polymer Interlayer

Abstract

Defect-mediated leakage at charge-selective contacts fundamentally limits the performance of colloidal quantum dot (QD) short-wave infrared (SWIR) photodiodes. Here, we address this challenge by inserting a thin conjugated polymer (PM6) interlayer between the PbS-EDT hole transport layer and the MoO_x electrode. This interlayer suppresses interfacial trap-assisted transport, reduces leakage pathways, and stabilizes charge dynamics, thereby achieving a more regulated interfacial transport regime. Consequently, the PM6-modified devices exhibit a markedly reduced dark current density of 70.1 nA/cm² at −0.5 V, a high external quantum efficiency of 82.56% (zero bias) at 1300 nm, and a significantly suppressed noise spectral density, leading to an enhanced specific detectivity of 2.62 × 10¹¹ Jones. Our findings establish polymer interlayer engineering as a simple and scalable approach to realize low-noise, high-stability SWIR photodetectors.