In-situ methylammonium chloride assisted perovskite crystallization strategy for high-performance solar cells
Weiwei Zuo a, Michael Saliba a
a Institut für Photovoltaik (ipv), Universität Stuttgart, Pfaffenwaldring 47, D-70569 Stuttgart, Deutschland
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Poster, Weiwei Zuo, 153
Publication date: 20th April 2022

The optimization of perovskite crystallization is critical to achieving high-performance perovskite solar cells (PSCs). In the standard crystallization methods, the additives play an important role not only in optimizing the crystallization but also passivating the defect states of perovskite films. Methylammonium chloride (MACl) is one of the frequently used additives in this regard. However, the performing mechanism MACl in the perovskite crystallization process still needs more investigation. We investigated the role of MACl vapor concentration on the fabrication of chlorine-doped perovskite films and studied the process of crystallization of chlorine-doped perovskites using in-situ 2D-GIXRD and in-situ real-time X-ray diffraction. We found that an external chlorine source with a higher MACl vapor pressure is appropriate for the crystallization of perovskite crystals and also optimizes the quality of perovskite films. Compared to the external chlorine source, the internal chlorine source in our experiment is uniformly distributed in the perovskite film and forms more pinholes randomly during annealing. What's more, MACl vapor from internal chlorine cannot provide enough momentum to support crystallization, and processed perovskite films are not densified. As demonstrated, MAPbI3-xClx based PSCs champion cells present the PCEs of 15.80%, 17.01% and 18.69% under these three conditions, respectively. Considering the beneficial effects of a higher concentration of MACl vapor, we fabricated films based on MAPbI3 using this treatment. SEM images show an evident improvement in morphology for the films processed with MACl vapor treatment. This difference could also be seen in cell performance, where the PCE of the champion cell improved from 19.3% to 20.9%. In a word, MACl vapor is presented as an easy and universal method to enhance the performance of perovskite solar cells.

M.S. and W.-W.Z. acknowledge the German Research Foundation for funding via the priority program SPP2196.

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