Enhanced power conversion efficiency via hybrid ligand exchange treatment of p-Type PbS quantum dots

Zhi Li Teh, Long Hu, Zhilong Zhang, Angus R. Gentle, Zihan Chen, Yijun Gao, Lin Yuan, Yicong Hu, Tom Wu, Shujuan Huang*, Robert J. Patterson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


PbS quantum dot solar cells (QDSCs) have emerged as a promising low-cost, solution-processable solar energy harvesting device and demonstrated good air stability and potential for large-scale commercial implementation. PbS QDSCs achieved a record certified efficiency of 12% in 2018 by utilizing an n+-n-p device structure. However, the p-type layer has generally suffered from low carrier mobility due to the organic ligand 1,2-ethanedithiol (EDT) that is used to modify the quantum dot (QD) surface. The low carrier mobility of EDT naturally limits the device thickness as the carrier diffusion length is limited by the low mobility. Herein, we improve the properties of the p-type layer through a two-step hybrid organic ligand treatment. By treating the p-type layer with two types of ligands, 3-mercaptopropionic acid (MPA) and EDT, the PbS QD surface was passivated by a combination of the two ligands, resulting in an overall improvement in open-circuit voltage, fill factor, and current density, leading to an improvement in the cell efficiency from 7.0 to 10.4% for the champion device. This achievement was a result of the improved QD passivation and a reduction in the interdot distance, improving charge transport through the p-type PbS quantum dot film.

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Original languageEnglish
Pages (from-to)22751-22759
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number20
Publication statusPublished - 20 May 2020


  • PbS quantum dot
  • quantum dot solar cell
  • p-type layer
  • ligand exchange
  • interdot distance


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