Temperature-Dependent Interplay between Structural and Charge Carrier Dynamics in CsMAFA-Based Perovskites

Jiashang Zhao, Xiaohui Liu, Zijin Wu, Bahiya Ibrahim, Jos Thieme, Geert Brocks, Shuxia Tao, Lars J. Bannenberg, Tom J. Savenije (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

State-of-the-art triple cation, mixed halide perovskites are extensively studied in perovskite solar cells, showing very promising performance and stability. However, an in-depth fundamental understanding of how the phase behavior in Cs0.05FA0.85MA0.10Pb(I0.97Br0.03)3 (CsMAFA) affects the optoelectronic properties is still lacking. The refined unit cell parameters a and c in combination with the thermal expansion coefficients derived from X-ray diffraction patterns reveal that CsMAFA undergoes an α–β phase transition at ≈280 K and another transition to the γ-phase at ≈180 K. From the analyses of the electrodeless microwave photoconductivity measurements it is shown that shallow traps only in the γ-phase negatively affect the charge carrier dynamics. Most importantly, CsMAFA exhibits the lowest amount of microstrain in the β-phase at around 240 K, corresponding to the lowest amount of trap density, which translates into the longest charge carrier diffusion length for electrons and holes. Below 200 K a considerable increase in deep trap states is found most likely related to the temperature-induced compressive microstrain leading to a huge imbalance in charge carrier diffusion lengths between electrons and holes. This work provides valuable insight into how temperature-dependent changes in structure affect the charge carrier dynamics in FA-rich perovskites.

Original languageEnglish
Article number2311727
Number of pages13
JournalAdvanced Functional Materials
Volume34
Issue number13
Early online date22 Dec 2023
DOIs
Publication statusPublished - 25 Mar 2024

Funding

J.Z. acknowledges the CSC (China Scholarship Council) for funding, File No. 201906360169. Z.W. and S.T. acknowledge the VIDI (Project No. VI.Vidi.213.091) from NWO, the Netherlands. Robert Dankelman and Jin Yan are acknowledged for their help with the low‐temperature XRD and SEM measurements, respectively.

FundersFunder number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
China Scholarship Council201906360169

    Keywords

    • charge carrier dynamics
    • metal halide perovskites
    • microstrain
    • phase structure
    • shallow trap states
    • time-resolved microwave conductivity

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