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Electro-optics of perovskite solar cells

Nature Photonics volume 9, pages 106112 (2015) | Download Citation

Abstract

Organohalide-perovskite solar cells have emerged as a leading next-generation photovoltaic technology. However, despite surging efficiencies, many questions remain unanswered regarding the mechanisms of operation. Here we report a detailed study of the electro-optics of efficient CH3NH3PbI3-perovskite-only planar devices. We report the dielectric constants over a large frequency range. Importantly, we found the real part of the static dielectric constant to be 70, from which we estimate the exciton-binding energy to be of order 2 meV, which strongly indicates a non-excitonic mechanism. Also, Jonscher's Law behaviour was consistent with the perovskite having ionic character. Accurate knowledge of the cell's optical constants allowed improved modelling and design, and using this information we fabricated an optimized device with an efficiency of 16.5%. The optimized devices have 100% spectrally flat internal quantum efficiencies and minimal bimolecular recombination. These findings establish systematic design rules to achieve silicon-like efficiencies in simple perovskite solar cells.

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Acknowledgements

P.L.B. is a University of Queensland (UQ) Vice Chancellor's Senior Research Fellow and P.M. is an Australian Research Council Discovery Outstanding Researcher Award Fellow. A.A. was supported by a UQ International Postgraduate Award. Q.L. is supported by an International Postgraduate Research Scholarship and R.C.R.N. was supported by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Future Manufacturing Flagship: Flexible Transparent Electrodes for Plastic Electronics Cluster, which includes The University of Queensland, University of Technology, Sydney, and Flinders University. We acknowledge funding from the University of Queensland (Strategic Initiative – Centre for Organic Photonics & Electronics). This work was performed in part at the Queensland node of the Australian National Fabrication Facility, a company established under the National Collaborative Research Infrastructure Strategy to provide nano- and microfabrication facilities for Australia's researchers. This Program has also been supported by the Australian Government through the Australian Renewable Energy Agency, Australian Centre for Advanced Photovoltaics. Responsibility for the views, information or advice expressed herein is not accepted by the Australian Government. We thank the Institute for Materials Research and Engineering (Singapore) for supplying the DPP-DTT and S. Watkins at CSIRO for photoelectron spectroscopy in air measurements.

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  1. Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, St Lucia Campus, Brisbane 4072, Australia

    • Qianqian Lin
    • , Ardalan Armin
    • , Ravi Chandra Raju Nagiri
    • , Paul L. Burn
    •  & Paul Meredith

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Contributions

Q.L. synthesized the MAI, prepared perovskite films and performed the basic characterization. Q.L. fabricated the solar-cell devices and Q.L. and A.A. tested them. Q.L., A.A., P.M. and P.L.B. designed the devices and experiments. R.C.R.N. and P.M. performed the spectroscopic ellipsometry and reflectometry and R.C.R.N., P.M. and A.A. fitted the data. A.A. and P.M. carried out the dielectric constant/binding energy analysis. All the authors contributed in writing the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Paul L. Burn or Paul Meredith.

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DOI

https://doi.org/10.1038/nphoton.2014.284

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