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Band filling with free charge carriers in organometal halide perovskites

Nature Photonics 8, 737–743 (2014) | Download Citation

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Abstract

The unique and promising properties of semiconducting organometal halide perovskites have brought these materials to the forefront of solar energy research. Here, we present new insights into the excited-state properties of CH3NH3PbI3 thin films through femtosecond transient absorption spectroscopy measurements. The photoinduced bleach recovery at 760 nm reveals that band-edge recombination follows second-order kinetics, indicating that the dominant relaxation pathway is via recombination of free electrons and holes. Additionally, charge accumulation in the perovskite films leads to an increase in the intrinsic bandgap that follows the Burstein–Moss band filling model. Both the recombination mechanism and the band-edge shift are studied as a function of the photogenerated carrier density and serve to elucidate the behaviour of charge carriers in hybrid perovskites. These results offer insights into the intrinsic photophysics of semiconducting organometal halide perovskites with direct implications for photovoltaic and optoelectronic applications.

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Acknowledgements

The authors thank J. Christians for his input on perovskite film preparation and discussion of experimental outcomes. The authors thank G. Hartland and M. Kuno for their commentary and interpretation of experimental results. The authors acknowledge the Center for Sustainable Energy at Notre Dame (cSEND) Materials Characterization Facilities for the use of the Bruker DektakXT profilometer. The research described herein was supported by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the US Department of Energy (award DE-FC02-04ER15533). This is contribution number NDRL No. 5004 from the Notre Dame Radiation Laboratory.

Author information

    • Joseph S. Manser
    •  & Prashant V. Kamat

    Present address: Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA

Affiliations

  1. Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA

    • Joseph S. Manser
    •  & Prashant V. Kamat

  2. Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA

    • Prashant V. Kamat

Authors

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Contributions

J.S.M. and P.V.K. conceived the original experimental ideas and details. J.S.M. carried out all aspects of film preparation and optical measurements. J.S.M. prepared the figures and wrote the initial draft. Both authors contributed to the discussion, analysis and writing of the final paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Prashant V. Kamat.

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DOI

https://doi.org/10.1038/nphoton.2014.171

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