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A‐Site Management for Highly Crystalline Perovskites
Author(s) -
Si Haonan,
Zhang Zheng,
Liao Qingliang,
Zhang Guangjie,
Ou Yang,
Zhang Suicai,
Wu Hualin,
Wu Jing,
Kang Zhuo,
Zhang Yue
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201904702
Subject(s) - materials science , crystallization , supersaturation , perovskite (structure) , chemical physics , crystal (programming language) , ultrafast laser spectroscopy , iodide , spectroscopy , crystallography , chemical engineering , chemistry , inorganic chemistry , programming language , physics , organic chemistry , quantum mechanics , computer science , engineering
An in‐depth understanding and effective suppression of nonradiative recombination pathways in perovskites are crucial to their crystallization process, in which supersaturation discrepancies at different time scales between CH 3 NH 3 I (MAI, methylammonium iodide) and PbI 2 remain a key issue. Here, an A‐site management strategy via the introduction of an A‐site placeholder cation, NH 4 + , to offset the deficient MA + precipitation by occupying the cavity of Pb–I framework, is proposed. The temporarily remaining NH 4 + is substituted by subsequently precipitated MA + . The temperature‐dependent crystallization process with the generation and consumption of a transient phase is sufficiently demonstrated by the dynamic changes in crystal structure characteristic peaks through in situ grazing‐incidence X‐ray diffraction and the surface potential difference evolution through temperature‐dependent Kelvin probe force microscopy. A highly crystalline perovskite is consequently acquired, indicated by the enlarged grain size, lowered nonradiative defect density, prolonged carrier lifetime, and fluorescence lifetime imaging. Most importantly, it is identified that the A‐site I MA defect is responsible for such crystal quality optimization based on theoretical calculations, transient absorption, and deep‐level transient spectroscopy. Furthermore, the universality of the proposed A‐site management strategy is demonstrated with other mixed‐cation perovskite systems, indicating that this methodology successfully provides guidance for synthesis route design of highly crystalline perovskites.