Probing the Origin of the Open Circuit Voltage in Perovskite Quantum Dot Photovoltaics

Brian Wieliczka, Jose Marquez, Alexandra Bothwell, Qian Zhao, Taylor Moot, Kaitlyn VanSant, Andrew Ferguson, Thomas Unold, Darius Kuciauskas, Joseph Luther

Research output: Contribution to journalArticlepeer-review

17 Scopus Citations

Abstract

Perovskite quantum dots (PQDs) have many properties that make them attractive for optoelectronic applications, including expanded compositional tunability and crystallographic stabilization. While they have not achieved the same photovoltaic (PV) efficiencies of top-performing perovskite thin films, they do reproducibly show high open circuit voltage (VOC) in comparison. Further understanding of the VOC attainable in PQDs as a function of surface passivation, contact layers, and PQD composition will further progress the field and may lend useful lessons for non-QD perovskite solar cells. Here, we use photoluminescence-based spectroscopic techniques to understand and identify the governing physics of the VOC in CsPbI3 PQDs. In particular, we probe the effect of the ligand exchange and contact interfaces on the VOC and free charge carrier concentration. The free charge carrier concentration is orders of magnitude higher than in typical perovskite thin films and could be tunable through ligand chemistry. Tuning the PQD A-site cation composition via replacement of Cs+ with FA+ maintains the background carrier concentration but reduces the trap density by up to a factor of 40, reducing the VOC deficit. These results dictate how to improve PQD optoelectronic properties and PV device performance and explain the reduced interfacial recombination observed by coupling PQDs with thin-film perovskites for a hybrid absorber layer.

Original languageAmerican English
Pages (from-to)19334-19344
Number of pages11
JournalACS Nano
Volume15
Issue number12
DOIs
StatePublished - 28 Dec 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-79021

Keywords

  • electronic traps
  • open circuit voltage
  • perovskite quantum dot
  • quasi-Fermi level splitting
  • solar cell
  • time-resolved photoluminescence

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