Multifunctional sodium phytate as buried interface Passivator for high efficiency and stable planar perovskite solar cells

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-11, Vol.500, p.157212, Article 157212
• Main Authors: Su, Haijun, Liu, Congcong, Fan, Huichao, Guo, Yinuo, Guo, Min, Zhang, Zhuo
• Format: Article
• Language: English
• Subjects: Buried interface defects; Humidity stability; Perovskite solar cells; Sodium phytate
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.157212

Sodium phytate (SP) is employed to passivate the buried interface defects of SnO2/perovskite, thus achieving comprehensive improvement of SnO2 ETL, perovskite film, and interface heterojunction. The six PO42- groups in SP can provide multiple chelating sites to bind closely with uncoordinated Sn2+, which improve the quality of SnO2 ETL and passivate the buried interface defects. SP can raise the surface energy of SnO2 film, promote the growth of perovskite grains and increase the average grain size of perovskite film. The synergistic passivation of buried interface defects of SnO2/perovskite enormously improves the photoelectric performance of PSCs. [Display omitted] •Sodium phytate (SP) is employed to passivate the buried interface defects of SnO2/perovskite.•Six electron-donating groups (PO42-) in SP provide multiple chelating sites to bind firmly with uncoordinated Sn2+.•SP can promote the growth of perovskite grains and increase the average grain size of perovskite film.•The PCE of PSCs based on SP-SnO2 achieves 22.29%, which is 14.0% higher than that of the SnO2-based PSCs. The buried interface defects of SnO2 electron transport layer (ETL)/perovskite limit the enhancement of photoelectric conversion efficiency (PCE) and stability of perovskite solar cells (PSCs) based on SnO2. Here, sodium phytate (SP) is employed as a complex molecule for passivating the buried interface defects of SnO2/perovskite, thus achieving comprehensive improvement of SnO2 ETL, perovskite film, and interface heterojunction. It is found that the six electron-donating groups (PO42-) in SP can provide multiple chelating sites to bind closely with uncoordinated Sn2+ at the buried SnO2/perovskite interface, thereby enhancing the quality of SnO2 ETL and passivating the buried interface defects. SP can raise the surface energy of SnO2 ETL, inhibit perovskite nucleation, and improve the average grain size of perovskite film from 530 nm to 665 nm. Thus, the efficiency of PSC made with SP-SnO2 is dramatically enhanced from 19.55 % to 22.29 %, which is 14.0 % higher than that of the PSC made with SnO2 (19.55 %). The unencapsulated devices made with SP-SnO2 show excellent humidity stability, maintaining 84 % of their initial efficiency after 1000 h in an air environment with a relative humidity (RH) of 60 %, while SnO2-based PSCs remain only 58 %. The complexation strategy affords a universal method to passivate buried interface defects, revealing broad application prospects in efficient