Traps in the spotlight: How traps affect the charge carrier dynamics in Cs2AgBiBr6 perovskite
Caselli, Valentina M.; Thieme, Jos; Jöbsis, Huygen J.; Phadke, Sohan A.; Zhao, Jiashang; Hutter, Eline M.; Savenije, Tom J.
(2022) Cell Reports Physical Science, volume 3, issue 10, pp. 1 - 16
(Article)
Abstract
Suitable optoelectronic properties of lead halide perovskites make these materials interesting semiconductors for many applications. Toxic lead can be substituted by combining monovalent and trivalent cations, such as in Cs2AgBiBr6. However, efficiencies of Cs2AgBiBr6-based photovoltaics are still modest. To elucidate the loss mechanisms, in this report, we investigate charge dynamics
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in Cs2AgBiBr6 films by double-pulse excitation time-resolved microwave conductivity (DPE-TRMC). By exciting the sample with two laser pulses with identical wavelengths, we found a clear photoconductance enhancement induced by the second pulse even 30 μs after the first laser pulse. Modeling the DPE-TRMC results, complemented by photoluminescence and transient absorption, we reveal the presence of deep emissive electron traps, while shallow hole trapping is responsible for the long-lived transient absorption signals. These long-lived carriers offer interesting possibilities for X-ray detectors or photocatalysis. The DPE-TRMC methodology offers unique insight into the times involved in charge trapping and depopulation in Cs2AgBiBr6.
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Keywords: charge carrier dynamics, double-pulse excitation, excitons, lead-free perovskites, photoluminescence, thin film, time-resolved microwave conductance, transient absorption, trap states, General Chemistry, General Materials Science, General Engineering, General Energy, General Physics and Astronomy
ISSN: 2666-3864
Publisher: Cell Press
Note: Funding Information: V.M.C. and T.J.S. acknowledge funding from the Dutch Research Council (NWO), grant no. 739.017.004. H.J.J. and E.M.H. acknowledge funding from the Dutch Research Council (NWO) under grant no. VI.Veni.192.034. H.J.J. and E.M.H. are supported further by the Advanced Research Center Chemical Building Blocks Consortium (ARC CBBC). V.M.C. prepared the samples following the procedure developed in collaboration with S.A.P. Sample characterization (absorption, PL, X-ray diffraction [XRD], SEM, DPE-TRMC, and TRPL) and data analysis have been performed by V.M.C. under the supervision of T.J.S. TA measurements have been performed by H.J.J. supervised by E.M.H. The manuscript has been written by V.M.C. and T.J.S. with the contributions of E.M.H. and H.J.J. The authors declare no competing interests. Funding Information: V.M.C. and T.J.S. acknowledge funding from the Dutch Research Council ( NWO ), grant no. 739.017.004 . H.J.J. and E.M.H. acknowledge funding from the Dutch Research Council (NWO) under grant no. VI.Veni.192.034. H.J.J. and E.M.H. are supported further by the Advanced Research Center Chemical Building Blocks Consortium (ARC CBBC). Publisher Copyright: © 2022 The Author(s)
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