Reversible Removal of Intermixed Shallow States by Light Soaking in Multication Mixed Halide Perovskite Films.
ACS energy letters
American Chemical Society (ACS)
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Guo, D., Andaji Garmaroudi, Z., Abdi-Jalebi, M., Stranks, S., & Savenije, T. J. (2019). Reversible Removal of Intermixed Shallow States by Light Soaking in Multication Mixed Halide Perovskite Films.. ACS energy letters, 4 (10), 2360-2367. https://doi.org/10.1021/acsenergylett.9b01726
The highest reported efficiencies of metal halide perovskite (MHP) solar cells are all based on mixed perovskites, such as (FA,MA,Cs)Pb(I1–xBrx)3. Despite demonstrated structural changes induced by light soaking, it is unclear how the charge carrier dynamics are affected across this entire material family. Here, various (FA,MA,Cs)Pb(I1–xBrx)3 perovskite films are light-soaked in nitrogen, and changes in optoelectronic properties are investigated through time-resolved microwave conductivity (TRMC) and optical and structural techniques. To fit the TRMC decay kinetics obtained for pristine (FA,MA,Cs)Pb(I1–xBrx)3 for various excitation densities, additional shallow states have to be included, which are not required for describing TRMC traces of single-cation MHPs. These shallow states can, independently of x, be removed by light soaking, which leads to a reduction in the imbalance between the diffusional motion of electrons and holes. We interpret the shallow states as a result of initially well-intermixed halide distributions, which upon light soaking segregate into domains with distinct band gaps.
Z.A.-G. acknowledges funding from a Winton Studentship and ICON Studentship from the Lloyd’s Register Foundation. M.A.-J. thanks Cambridge Materials Limited and EPSRC (Grant Number EP/M005143/1) for their funding and technical support. S.D.S. acknowledges the Royal Society and Tata Group (UF150033) for funding.
Royal Society (UF150033)
External DOI: https://doi.org/10.1021/acsenergylett.9b01726
This record's URL: https://www.repository.cam.ac.uk/handle/1810/296821
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