Solvent Engineering in Ligand Exchange of the Hole Transport Layer Enables High-Performance PbS Quantum Dot Solar Cells

Xiao Liu; Zeyao Han; Defei Yuan; Yong Chen; Ziqi Lu; Li Zhang; Yang Liu; Lilei Hu; Bin Sun

doi:10.1021/acs.jpclett.4c03019

Solvent Engineering in Ligand Exchange of the Hole Transport Layer Enables High-Performance PbS Quantum Dot Solar Cells

J Phys Chem Lett. 2025 Jan 17:857-862. doi: 10.1021/acs.jpclett.4c03019. Online ahead of print.

Authors

Xiao Liu¹, Zeyao Han¹, Defei Yuan¹, Yong Chen¹, Ziqi Lu¹, Li Zhang¹, Yang Liu², Lilei Hu³, Bin Sun¹

Affiliations

¹ State Key Laboratory of Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), School of Material Science and Engineering, Nanjing University of Posts and Telecommunications (NJUPT), 9 Wenyuan Rd., Nanjing 210023, China.
² School of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
³ School of Microelectronics, Shanghai University, Shanghai 200240, China.

PMID: 39818778
DOI: 10.1021/acs.jpclett.4c03019

Abstract

The performance of lead sulfide colloidal quantum dot (PbS-CQD) solar cells has long been hindered by interface defects in the transport layer. Traditionally, 1,2-ethanedithiol (EDT), used in solid-state ligand exchange, has been a common choice as the hole transport layer (HTL) in many PbS-CQD solar cells. However, the rapid reaction rate and chain length mismatch (shorter-chain EDT versus longer-chain oleic acid) during the ligand exchange process often introduce crack defects in the HTL film, resulting in an unexpected low performance. In this work, ethyl acetate (EA) was introduced into acetonitrile (ACN) solution to slow down the ligand exchange rate. With EA's assistance, a high-quality HTL film with fewer cracks was achieved, leading to a reduced trap density from 2.26 × 10¹⁶ cm^-3 to 1.85 × 10¹⁶ cm^-3. Consequently, this led to an improved V_OC by 27.5 mV and an increased power conversion efficiency (PCE) from 11.01% to 12.16%.