Investigating two-step MAPbI3 thin film formation during spin coating by simultaneous in situ absorption and photoluminescence spectroscopy
Investigating two-step MAPbI3 thin film formation during spin coating by simultaneous in situ absorption and photoluminescence spectroscopy
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DOI：
10.1039/c9ta12409h
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发表时间：
2020-03-14
影响因子：
11.9
通讯作者：
Panzer, Fabian
中科院分区：
文献类型：
--
作者：
Chauhan, Mihirsinh;Zhong, Yu;Panzer, Fabian
到目前为止，两步法是形成卤化物钙钛矿薄膜的一条很有吸引力的路线。然而，在PbI2上旋涂甲基碘化铵(MAI)的情况下，成膜动力学的基本认识还没有建立。在此，我们应用原位光学光谱的方法，通过旋涂两步形成了卤化物钙钛矿型MAPbI(3)模型薄膜。我们详细地识别和分析了光致发光中的光学特征和相应的处理过程中的吸收光谱。我们发现，薄膜的形成经历了五个连续的步骤，包括通过界面结晶形成MAPbI3覆盖层和发生强烈的溶解-再结晶过程。考虑到光致发光光谱中的限制和自吸收效应，以及相应的吸收光谱，可以量化初始界面结晶的生长速率，在我们的工艺条件下，该生长速率为11 nm S(-1)。我们发现，主要的溶解-再结晶过程以445nmS(-1)的速率发生，强调了它在整个加工过程中的重要性。
To date, the two-step processing method represents an attractive route for the thin film formation of halide perovskites. However, a fundamental understanding of the film formation dynamics in the case of spin coating methylammonium iodide (MAI) on PbI2 has not been established yet. Here we apply in situ optical spectroscopy during the two-step film formation of the model halide perovskite MAPbI(3) via spin coating. We identify and analyze in detail the optical features that occur in the photoluminescence and the corresponding absorption spectra during processing. We find that the film formation takes place in five consecutive steps, including the formation of a MAPbI3 capping layer via an interface crystallization and the occurrence of an intense dissolution-recrystallization process. Consideration of confinement and self-absorption effects in the PL spectra, together with consideration of the corresponding absorption spectra allows quantification of the growth rate of the initial interface crystallization, which is found to be 11 nm s(-1) under our processing conditions. We find that the main dissolution-recrystallization process happens at a rate of 445 nm s(-1), emphasizing its importance to the overall processing.