Simultaneous Surface Modification and Defect Passivation on Tin Oxide–Perovskite Interfaces using Pseudohalide Salt of Sodium Tetrafluoroborate

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Author list: Soe, Kay Thi; Thansamai, Somya; Thongprong, Non; Ruengsrisang, Waranchit; Muhammad, Ibrahim Adam;
Ketsombun, Ekkaphop; Supruangnet, Ratchadaporn; Kaewprajak, Anusit; Kumnorkaew, Pisist; Saetang, Viboon; Supasai, Thidarat; Rujisamphan, Nopporn;

Publisher: Wiley

Publication year: 2023

Journal acronym: Sol. RRL

Volume number: 7

Issue number: 1

ISSN: 2367-198X

eISSN: 2367-198X

URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85142259645&doi=10.1002%2fsolr.202200964&partnerID=40&md5=d036e3efb4c74beda8582b7acd8a3a2d

Languages: English-Great Britain (EN-GB)

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Abstract

Passivating electron-transporting layers (ETLs) with alkali salts have demonstrated a facial approach that is essential in healing defective surfaces, consequently improving the functionality and stability of perovskite-based solar cells (PSCs). Herein, the pseudohalide salt of sodium tetrafluoroborate, whose anions have a higher electronegativity than other halide salts (i.e., iodide and chloride), with the potential to passivate the surface of tin oxide while enhancing the optoelectronic properties of a perovskite film, is presented. Meanwhile, the density functional theory calculations show that BF4−/F− ions exhibit a robust ionic interaction with an uncoordinated Sn4+ site. In contrast, the Na ion is bound to an oxygen atom of the OH− group, which helps reduce surface defect states and improves charge transfer properties. Thus, the best PSC exhibits a current density of 23.51 mA cm−2, an open-circuit voltage of 1.10 V, and an excellent fill factor of 80.48, providing an efficiency of 20.82%, which exceeds that of a control device (18.38%). Importantly, the retention of the power conversion efficiency on NaBF4-based PSCs without encapsulation is 18.44% after 1000 h of aging under ambient conditions, whereas the retention of a control device is only 16.08%. © 2022 Wiley-VCH GmbH.

Keywords

passivation, SnO2, sodium tetrafluoroborate