Carriers trapping and recombination: the role of defect physics in enhancing the open circuit voltage of metal halide perovskite solar cells

Leijtens, Tomas and Eperon, Giles E. and Barker, Alex J. and Grancini, Giulia and Zhang, Wei and Ball, James M. and Srimath Kandada, Ajay and Snaith, Henry J. and Petrozza, Annamaria (2016) Carriers trapping and recombination: the role of defect physics in enhancing the open circuit voltage of metal halide perovskite solar cells. Energy and Environmental Science, 9 (11). pp. 3472-3481. ISSN 1754-5692

Full content URL: http://dx.doi.org/10.1039/C6EE01729K

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Abstract

One of the greatest attributes of metal halide perovskite solar cells is their surprisingly low loss in potential between bandgap and open-circuit voltage, despite the fact that they suffer from a non-negligible density of sub gap defect states. Here, we use a combination of transient and steady state photocurrent and absorption spectroscopy to show that CH3NH3PbI3 films exhibit a broad distribution of electron traps. We show that the trapped electrons recombine with free holes unexpectedly slowly, on microsecond time scales, relaxing the limit on obtainable Open-Circuit Voltage (Voc) under trap-mediated recombination conditions. We find that the observed VOCs in such perovskite solar cells can only be rationalized by considering the slow trap mediated recombination mechanism identified in this work. Our results suggest that existing processing routes may be good enough to enable open circuit voltages approaching 1.3 V in ideal devices with perfect contacts.

Keywords:Defect Physics, Open Circuit Voltage, Perovskite Solar Cells, JCOpen
Subjects:F Physical Sciences > F200 Materials Science
J Technologies > J910 Energy Technologies
F Physical Sciences > F310 Applied Physics
Divisions:College of Science > School of Chemistry
ID Code:24110
Deposited On:16 Sep 2016 10:20

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