Reducing Saturation-Current Density to Realize High-Efficiency Low-Bandgap Mixed Tin-Lead Halide Perovskite Solar Cells

Chuanxiao Xiao, Chun Sheng Jiang, Mowafak Al-Jassim, Kai Zhu, Chongwen Li, Zhaoning Song, Dewei Zhao, Biwas Subedi, Niraj Shrestha, Maxwell Junda, Changlei Wang, Randy Ellingson, Nikolas Podraza, Yanfa Yan

Research output: Contribution to journalArticlepeer-review

282 Scopus Citations

Abstract

The unsatisfactory performance of low-bandgap mixed tin (Sn)–lead (Pb) halide perovskite subcells has been one of the major obstacles hindering the progress of the power conversion efficiencies (PCEs) of all-perovskite tandem solar cells. By analyzing dark-current density and distribution, it is identified that charge recombination at grain boundaries is a key factor limiting the performance of low-bandgap mixed Sn–Pb halide perovskite subcells. It is further found that bromine (Br) incorporation can effectively passivate grain boundaries and lower the dark current density by two–three orders of magnitude. By optimizing the Br concentration, low-bandgap (1.272 eV) mixed Sn–Pb halide perovskite solar cells are fabricated with open-circuit voltage deficits as low as 0.384 V and fill factors as high as 75%. The best-performing device demonstrates a PCE of >19%. The results suggest an important direction for improving the performance of low-bandgap mixed Sn–Pb halide perovskite solar cells.

Original languageAmerican English
Article number1803135
Number of pages9
JournalAdvanced Energy Materials
Volume9
Issue number3
DOIs
StatePublished - 2019

Bibliographical note

Publisher Copyright:
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

NREL Publication Number

  • NREL/JA-5K00-72548

Keywords

  • dark saturation current
  • grain boundary passivation
  • low-bandgap perovskites
  • perovskite solar cells

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