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

## TL;DR

This paper introduces a new method to improve the efficiency of quantum dot solar cells by using a molecule that fixes defects and transfers energy.

## Contribution

The paper introduces a dual-functional ETL that combines defect passivation and triplet energy transfer for PbS CQD PVs.

## Key findings

- ACA passivates ZnO defects, reducing trap-assisted recombination.
- ACA generates triplet excitons that transfer energy to PbS CQDs, boosting photocurrent.
- Devices with ACA-treated ETLs achieved 11.55% power conversion efficiency, up from 10.48%.

## Abstract

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.

An acene‐based donor incorporated into the electron transport layer enables triplet energy transfer to PbS colloidal quantum dots and improves defect passivation, resulting in enhanced photovoltaic device performance.© 2025 WILEY‐VCH GmbH