Enhancing Quantum Dot Photovoltaic Efficiency Through Defect Passivation and Triplet Energy Transfer with 9‐Anthracenecarboxylic Acid

A dual‐functional electron transport layer (ETL) is reported for PbS colloidal quantum dot (CQD) photovoltaics by incorporating 9‐anthracenecarboxylic acid (ACA) into a zinc oxide (ZnO) matrix. Despite its favorable electron transport characteristics and appropriate band alignment, intrinsic defects in ZnO, such as oxygen vacancies, remain a limiting factor in device performance. The carboxylate functional group of ACA effectively passivates these defects, thereby reducing trap‐assisted recombination. Moreover, ACA, an acene‐based π‐conjugated molecule, efficiently generates triplet excitons. These triplets undergo triplet energy transfer to the PbS CQD layer, enhancing photocurrent generation. Owing to these synergistic effects, CQD photovoltaics (PVs) incorporating ACA‐treated ZnO ETLs exhibit enhanced open‐circuit voltage and short‐circuit current density, resulting in a higher power conversion efficiency of 11.55% compared to 10.48% for control devices. This strategy highlights the combined advantages of electronic defect passivation and triplet exciton harvesting in PbS CQD PVs.