Photo-Doping of Spiro-OMeTAD for Highly Stable and Efficient Perovskite Solar Cells

Seul-Gi Kim, George Fish, Etienne Socie, Aaron Terpstra, Dong-Am Park, Kai Zhu, Michael Gratzel, Jacques-E. Moser, Nam-Gyu Park

Research output: Contribution to journalArticlepeer-review

Abstract

A widely used component of high-efficiency perovskite solar cells (PSCs) is the molecular hole-transport material (HTM) spiro-OMeTAD. This organic solid needs to be p-doped to acquire sufficient hole conductivity. However, the conventional doping method using LiTFSI in the air is slow, sensitive to the environment, and may lead to the deterioration of the PSCs by unintended oxidation or dopant migration. It is thus highly desirable to develop fast doping approaches that avoid exposing the PSC to ambient air and easy-to-move dopant ions. We report here that light absorption by spiro-OMeTAD itself triggers redox photochemistry that has so far been ignored. Strikingly, we found that Y(III) or La(III)-tBP complexes catalyze the symmetry-breaking charge separation of photo-excited spiro-OMeTAD, resulting in the efficient p-doping of the HTM. Using this photo-redox process, we realize PSCs with superior stability over cells using conventional doping that show no degradation under continuous illumination over 1,000 h.
Original languageAmerican English
Pages (from-to)1707-1722
Number of pages16
JournalJoule
Volume8
Issue number6
DOIs
StatePublished - 2024

NREL Publication Number

  • NREL/JA-5900-89954

Keywords

  • La(TFSI)3
  • perovskite solar cell
  • photo-doping
  • photo-redox
  • stability
  • Y(TFSI)3

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