Elimination of trap density by NH4Cl passivation for high-performance perovskite solar cells

• Published in: Applied physics. A, Materials science & processing Vol. 129; no. 11
• Main Authors: Yin, Qianliu, Zhang, Fanfan, Teng, Yanlin, Peng, Cong, Wang, Chaonan, Jin, Yonglong, Xu, Meifeng, Xu, Tian
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2023; Springer Nature B.V
• Subjects: Ammonium chloride; Applied physics; Characterization and Evaluation of Materials; Condensed Matter Physics; Density; Electromagnetic absorption; Grain boundaries; Grain size; Lead; Machines; Manufacturing; Materials science; Nanotechnology; Optical and Electronic Materials; Passivity; Performance enhancement; Perovskites; Photovoltaic cells; Physics; Physics and Astronomy; Precursors; Processes; Solar cells; Surfaces and Interfaces; Thin Films; Perovskite; Cl; Defect; NH; Passivation
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-023-07047-5

Different concentrations of NH 4 Cl are introduced to MAPbI 3 precursor solution, planar MAPbI 3 perovskite films, and solar cells’ performance with or without NH 4 Cl have been studied. The NH 4 Cl/MAPbI 3 films exhibit increased grain size and narrowed grain boundaries. The light absorption of perovskite films with different concentrations of NH 4 Cl was also evaluated. To understand the growth of perovskite films with NH 4 Cl added to perovskite precursor solutions, XRD and XPS spectroscopy were conducted on different perovskite film samples. By adding NH 4 Cl, the MAPbI 3 film shows good crystal quality and the shift of Pb peaks indicates that NH 4 Cl is not physically mixed but chemically incorporated into MAPbI 3 films. We attribute the effect to Cl ions of NH 4 Cl combining with free lead ions of MAPbI 3 so as to fill the vacancy of volatile I ions in the NH 4 Cl–MAPbI 3 films. The 20 mg NH 4 Cl-based device showed an enhanced performance of a PCE of 13.67% compared to the device without adding NH 4 Cl with a PCE of 10.24%. The introduction of 20 mg NH 4 Cl achieved the best passivation effect. Using a 20 mg NH 4 Cl device, the trap density can be reduced to 0.84 × 10 16  cm −3 , resulting in more efficient charge removal from the surface and improved performance.