Control over Ligand Exchange Reactivity in Hole Transport Layer Enables High-Efficiency Colloidal Quantum Dot Solar Cells

Margherita Biondi, Min Jae Choi, Seungjin Lee, Koen Bertens, Mingyang Wei, Ahmad R. Kirmani, Geonhui Lee, Hao Ting Kung, Lee J. Richter, Sjoerd Hoogland, Zheng Hong Lu, F. Pelayo García De Arquer, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Colloidal quantum dot (CQD) solar cells are solution-processed photovoltaic devices that exhibit promise in harvesting the infrared solar spectrum. Solid-state ligand exchange is the method employed to fabricate the CQD hole transport layer (HTL) in these cells: insulating oleic acid ligands are substituted with short thiol ligands (1,2-ethanedithiol) to create conductive p-type CQD solids. Thiols' high reactivity with the CQD surface results in rapid exchange, giving rise to aggregates of dots and unpassivated sites on dots, each contributing to sub-bandgap trap states. Here we report a strategy to minimize trap states in the CQD HTL by controlling the solvent type in the exchange. By employing a less volatile solvent, we achieve a slower reaction, leading to increased order and a 2 times reduced trap density in CQD solids. These improvements enable a power conversion efficiency of 13.1 ± 0.1% in CQD solar cells compared to control devices showing 12.4 ± 0.1%.

Original languageEnglish (US)
Pages (from-to)468-476
Number of pages9
JournalACS Energy Letters
Volume6
Issue number2
DOIs
StatePublished - Feb 12 2021

ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry

Fingerprint

Dive into the research topics of 'Control over Ligand Exchange Reactivity in Hole Transport Layer Enables High-Efficiency Colloidal Quantum Dot Solar Cells'. Together they form a unique fingerprint.

Cite this