Synergistic Interface Engineering via Buffer Layer and UVO Treatment for High‐Performance PbS Quantum Dot Near‐Infrared Photodiodes

ABSTRACT While PbS quantum dot (QD) photodetectors exhibit promising near‐infrared (NIR) response, their performance is limited by interfacial defects and damage caused by ligand‐exchange processes. This study introduces a dual‐interface engineering strategy: (I) A solution‐processable Poly‐TPD buffer layer is inserted between the PbS‐halide active layer and PbS‐EDT hole transport layer to mitigate EDT/acetonitrile‐induced interfacial damage and improve hole extraction; (II) A controlled UV‐ozone treatment is applied to the PbS‐EDT layer to enhance p‐doping density and reduce defect states. The optimized device achieves a dark current density as low as 74 nA cm ^{− 2} at ‐0.5 V, a responsivity of 0.42 A W ⁻¹ (at 1350 nm illumination), and a specific detectivity (D*) of 2.1 × 10 ¹² Jones, placing it among the higher‐performing solution‐processed PbS CQD photodiodes operating in the 1.3–1.4 µm range. This work provides a scalable approach for developing high‐performance solution‐processed NIR photodetectors.