Precise Control of Perovskite Crystallization Kinetics via Sequential A-Site Doping

Minchao Qin, Haibo Xue, Hengkai Zhang, Hanlin Hu, Kuan Liu, Yuhao Li, Zhaotong Qin, Junjie Ma, Hepeng Zhu, Keyou Yan, Guojia Fang, Gang Li, U. Ser Jeng, Geert Brocks, Shuxia Tao (Corresponding author), Xinhui Lu (Corresponding author)

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Abstract

Two-step-fabricated FAPbI3-based perovskites have attracted increasing attention because of their excellent film quality and reproducibility. However, the underlying film formation mechanism remains mysterious. Here, the crystallization kinetics of a benchmark FAPbI3-based perovskite film with sequential A-site doping of Cs+ and GA+ is revealed by in situ X-ray scattering and first-principles calculations. Incorporating Cs+ in the first step induces an alternative pathway from δ-CsPbI3 to perovskite α-phase, which is energetically more favorable than the conventional pathways from PbI2. However, pinholes are formed due to the nonuniform nucleation with sparse δ-CsPbI3 crystals. Fortunately, incorporating GA+ in the second step can not only promote the phase transition from δ-CsPbI3 to the perovskite α-phase, but also eliminate pinholes via Ostwald ripening and enhanced grain boundary migration, thus boosting efficiencies of perovskite solar cells over 23%. This work demonstrates the unprecedented advantage of the two-step process over the one-step process, allowing a precise control of the perovskite crystallization kinetics by decoupling the crystal nucleation and growth process.

Original languageEnglish
Article number2004630
Number of pages11
JournalAdvanced Materials
Volume32
Issue number42
Early online date16 Sept 2020
DOIs
Publication statusPublished - 20 Oct 2020

Funding

M.Q. and H.X. contributed equally to this work. The authors are grateful for the beam time and technical supports provided by 23A SWAXS beamline at NSRRC, Hsinchu. The authors acknowledge the financial support from the Research Grant Council of Hong Kong (RGC) (General Research Fund No. 14314216). H.X. acknowledges the funding from the China Scholarship Council (CSC). S.T. acknowledges funding by the Computational Sciences for Energy Research (CSER) tenure track program of Shell and NWO (Project number 15CST04-2), The Netherlands. G.L. thanks funding from RGC (CRF Group Research Grant C5037-18G). M.Q. and H.X. contributed equally to this work. The authors are grateful for the beam time and technical supports provided by 23A SWAXS beamline at NSRRC, Hsinchu. The authors acknowledge the financial support from the Research Grant Council of Hong Kong (RGC) (General Research Fund No. 14314216). H.X. acknowledges the funding from the China Scholarship Council (CSC). S.T. acknowledges funding by the Computational Sciences for Energy Research (CSER) tenure track program of Shell and NWO (Project number 15CST04‐2), The Netherlands. G.L. thanks funding from RGC (CRF Group Research Grant C5037‐18G).

FundersFunder number
RGC14314216
Research Grant Council of Hong Kong
Shell
Research Grants Council, University Grants Committee
Nederlandse Organisatie voor Wetenschappelijk Onderzoek15CST04‐2
China Scholarship Council

    Keywords

    • crystallization kinetics
    • perovskite solar cells
    • reaction enthalpy
    • sequential A-site doping
    • two-step method

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