Extracting Optical Bandgaps from Luminescence Images of Perovskite Solar Cells

Steven Johnston, Mowafak Al-Jassim, Hieu Nguyen, Boyi Chen, Jun Peng, Heping Shen, The Duong, Daniel Walter, Klaus Weber, Thomas White, Kylie Catchpole, Daniel Macdonald

Research output: Contribution to conferencePaperpeer-review


We report a camera-based method to capture optical bandgap images of perovskite solar cells (PSCs). It is fast and non-destructive. It can also provide micron-scale spatial resolution. This imaging technique utilizes well-defined and relatively symmetrical band-to-band luminescence spectra emitted from perovskite materials. Their spectra can be fitted with Gaussian functions whose peak locations are similar to absorption thresholds and thus represent the material optical bandgaps. We apply the technique to resolve relative variations in optical bandgaps across various PSCs, and to show optical bandgap inhomogeneity within the same device due to material degradation and impurities. Degradation and impurities were found to both cause optical bandgap shifts inside the materials. Our results are independently confirmed with photoluminescence and absorption spectroscopy.

Original languageAmerican English
Number of pages4
StatePublished - Jun 2019
Event46th IEEE Photovoltaic Specialists Conference, PVSC 2019 - Chicago, United States
Duration: 16 Jun 201921 Jun 2019


Conference46th IEEE Photovoltaic Specialists Conference, PVSC 2019
Country/TerritoryUnited States

Bibliographical note

Publisher Copyright:
© 2019 IEEE.

NREL Publication Number

  • NREL/CP-5K00-76325


  • bandgap
  • imaging
  • luminescence
  • perovskite
  • photovolta-ics


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