Colloidal Quantum Dot Solar Cell Band Alignment using Two-Step Ionic Doping

Koen Bertens, James Z. Fan, Margherita Biondi, Armin Sedighian Rasouli, Seungjin Lee, Peicheng Li, Bin Sun, Sjoerd Hoogland, F. Pelayo García De Arquer, Zheng Hong Lu, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Colloidal quantum dot (CQD) solar cells composed of ionic halide passivated active layers benefit from improved passivation and high carrier mobility because of short interparticle distance. However, non-ideal band alignment of the active layer limits the potential open-circuit voltage (VOC) produced by the solar cell. We initiated a suite of simulation-based studies of CQD solar cells and found a route to improved performance by increasing the degree of p-type behavior. Fluoride, while it is a p-type ionic ligand as desired, is incompatible with traditional ligand exchange processes. In prior studies, it has shown to etch the lead sulfide surface uncontrollably. Instead, we develop a multistep halide exchange method, in which the CQD active layer is doped with fluoride ions after ligand exchange. This new method prevents CQD surface etching without impeding charge transport, resulting in a statistically significant improvement in VOC, fill factor, and power conversion efficiency.

Original languageEnglish (US)
Pages (from-to)1583-1589
Number of pages7
JournalACS Materials Letters
Issue number12
StatePublished - Dec 7 2020

ASJC Scopus subject areas

  • General Chemical Engineering
  • Biomedical Engineering
  • General Materials Science


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