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; Xinhui Lu

doi:10.1002/adma.202004630

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

Adv Mater. 2020 Oct;32(42):e2004630. doi: 10.1002/adma.202004630. Epub 2020 Sep 16.

Authors

Minchao Qin¹, Haibo Xue², Hengkai Zhang³, Hanlin Hu⁴, Kuan Liu³, Yuhao Li¹, Zhaotong Qin¹, Junjie Ma⁵, Hepeng Zhu⁶, Keyou Yan⁶, Guojia Fang⁵, Gang Li³, U-Ser Jeng^{7

8}, Geert Brocks^{2

9}, Shuxia Tao², Xinhui Lu¹

Affiliations

¹ Department of Physics, The Chinese University of Hong Kong, Shatin, 999077, Hong Kong.
² Materials Simulation and Modelling and Center for Computational Energy Research, Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, 5600MB, The Netherlands.
³ Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Kowloon, 999077, Hong Kong.
⁴ Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, 7098 Liuxian Boulevard, Shenzhen, 518055, P. R. China.
⁵ Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan, 430072, P. R. China.
⁶ School of Environment and Energy, State Key Laboratory of Luminescent Materials and Devices, National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, South China University of Technology, Guangzhou, 510006, P. R. China.
⁷ National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu, 30076, Taiwan.
⁸ Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 30013, Taiwan.
⁹ Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, Enschede, 7500AE, The Netherlands.

PMID: 32939914
DOI: 10.1002/adma.202004630

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.

Keywords: crystallization kinetics; perovskite solar cells; reaction enthalpy; sequential A-site doping; two-step method.

Abstract

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