Moisture‐Resistant FAPbI3 Perovskite Solar Cell with 22.25 % Power Conversion Efficiency through Pentafluorobenzyl Phosphonic Acid Passivation

• Published in: ChemSusChem 2021-02, Vol.14 (4), p.1176-1183
• Main Authors: Akman, Erdi, Shalan, Ahmed Esmail, Sadegh, Faranak, Akin, Seckin
• Format: Article
• Language: English
• Subjects: Carrier recombination; Commercialization; Crystal defects; Efficiency; Energy conversion efficiency; Grain boundaries; Moisture resistance; passivation; Passivity; Perovskites; Phosphonic acids; Photovoltaic cells; Solar cells; stabilization; Surface stability
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202002707

Perovskite solar cells (PSCs) have shown great promise for photovoltaic applications, owing to their low‐cost assembly, exceptional performance, and low‐temperature solution processing. However, the advancement of PSCs towards commercialization requires improvements in efficiency and long‐term stability. The surface and grain boundaries of perovskite layer, as well as interfaces, are critical factors in determining the performance of the assembled cells. Defects, which are mainly located at perovskite surfaces, can trigger hysteresis, carrier recombination, and degradation, which diminish the power conversion efficiencies (PCEs) of the resultant cells. This study concerns the stabilization of the α‐FAPbI3 perovskite phase without negatively affecting the spectral features by using 2,3,4,5,6‐pentafluorobenzyl phosphonic acid (PFBPA) as a passivation agent. Accordingly, high‐quality PSCs are attained with an improved PCE of 22.25 % and respectable cell parameters compared to the pristine cells without the passivation layer. The thin PFBPA passivation layer effectively protects the perovskite layer from moisture, resulting in better long‐term stability for unsealed PSCs, which maintain >90 % of the original efficiency under different humidity levels (40–75 %) after 600 h. PFBPA passivation is found to have a considerable impact in obtaining high‐quality and stable FAPbI3 films to benefit both the efficiency and the stability of PSCs. Passive attack: The α‐FAPbI3 perovskite layer in a solar cell is stabilized without deteriorating the spectral features by passivating with 2,3,4,5,6‐pentafluorobenzyl phosphonic acid (PFBPA). High‐quality perovskite solar cells with an improved efficiency of 22.25 % was achieved with excellent moisture stability maintaining >90 % of its initial efficiency at high humidity levels.