Solvent modification to suppress halide segregation in mixed halide perovskite solar cells
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Solvent modification to suppress halide segregation in mixed halide perovskite solar cells Yaoyao Li1,2, Dandan Song1,2,*, Juan Meng1,2, Jie Dong1,2, Yao Lu1,2, Xiaomin Huo1,2, Ayman Maqsood1,2, Yuhang Song1, Suling Zhao1,2, Bo Qiao1,2, and Zheng Xu1,2,*
1
Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China 2 Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China
Received: 10 January 2020
ABSTRACT
Accepted: 17 April 2020
Mixed halide perovskite is essential to construct highly efficient tandem solar cells, whereas halide segregation is a main issue hindering their device efficiency for this kind of perovskite materials. Herein, we modify the solvents for the mixed halide precursor solution to suppress halide segregation during fabrication process. An alternative solvent, N-Methyl pyrrolidone (NMP), is used to replace commonly used solvent, dimethyl sulfoxide (DMSO). It is shown that the halide segregation and the resultant carrier recombination are notably suppressed. The improvements brought by NMP may correlate with its moderate Lewis base property, which modifies the crystallization process of the mixed halide perovskite film. Consequently, the device performance is greatly improved by using NMP. The device efficiency is increased from less than 10% for DMSO solvent to approach 14% for NMP solvent. This work provides a facile way to improve the device efficiency, which also highlights on the importance of the solvents on halide segregation.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Introduction Perovskite halides are ideal materials for optoelectronic devices like solar cells and light-emitting diodes [1–4]. Especially, perovskite solar cells (PSCs) exhibit the highest efficiency of thin-film solar cells, and their efficiency approaches the record efficiency of mc-silicon solar cells [5]. Further efficiency breakthrough relies on the new concepts which can break the Shockley–Queisser limit (SQ limit). Among these
concepts, the tandem solar cells are the most practicable technique [3, 6, 7]. Therefore, increasing studies focus on the properties and the fabrication techniques of the perovskite materials and the corresponding PSCs suitable for tandem solar cells [8–10]. In double-junction tandem solar cells, the PSCs are typically used as the top cell [11]. In this case, the ideal bandgap of the perovskite is calculated to be around 1.7 eV [12]. This bandgap can be realized by mixing halide perovskite APb(BrxI1-x)3 (A = Cs or
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https://doi.org/10.1007/s10853-020-04697-1
J Mater Sci
organic cation) with x = 0.4 [13, 14]. Though the mixed halide perovskite has similar crystal structure and composition as the iodide perovskite (APbI3), the device performance and the material stability are much inferior [15, 16]. These disadvantages mainly correlate with the halide segregation in mixed halide
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