Enhanced performance of CsPbI2Br perovskite solar cell through improving the solubility of the components in precursor

•Precisely improved the solubility of CsI in precursor and controlled the crystal growth of CsPbI2Br film.•The δ phase occurred during crystallization was suppressed after adding the acetamide.•Low defect density device was obtained because the Pb0 formed in control film was eliminated. As a key of...

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Bibliographic Details
Published in:Solar energy 2022-09, Vol.244, p.40-46
Main Authors: Liu, Shanjing, Xu, Xinyu, Xing, Chuwu, Ge, Guanming, Wang, Duofa, Zhang, Tianjin
Format: Article
Language:English
Subjects:
Crystallization
CsI
CsPbI2Br perovskite
Pb0
Solubility
δ phase
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Summary:•Precisely improved the solubility of CsI in precursor and controlled the crystal growth of CsPbI2Br film.•The δ phase occurred during crystallization was suppressed after adding the acetamide.•Low defect density device was obtained because the Pb0 formed in control film was eliminated. As a key of the perovskite growth, the properties of precursor influence the quality of film greatly. Among many properties, the solubility of the solute determines whether crystal film can form or the film with high quality. Therefore, we chose the small organic molecule acetamide (AT) with functional groups NH2 and CO as additive to improve the solubility of the original component CsI and regulate the crystallization of CsPbI2Br perovskite. Different from the Lewis acid-base interaction occurred between the additives and PbI2 reported by many researches, the hydrogen bond formed between the NH2 in AT and the I in CsI in CsPbI2Br perovskite precursor improved the activity and solubility of CsI, the corresponding effects caused the components in precursor participated in the crystallization and stabilized the crystal structure. And which excellent addition reflected in the suppressed unstable δ phase generated during the crystallization. As a consequence, the Pb0 roots in halogen vacancies in control film was also eliminated after added the AT, and the nonstoichiometric ratio in annealed film was further eliminated. In final, the power conversion efficiency (PCE) increased from the 10.24 % for control solar cell to 13.36 % for modified solar cell, and the stability has also been greatly improved.
ISSN:0038-092X
1471-1257
DOI:10.1016/j.solener.2022.07.038