In Situ Bonding Regulation of Surface Ligands for Efficient and Stable FAPbI3 Quantum Dot Solar Cells

• Published in: Advanced science Vol. 9; no. 35; pp. e2204476 - n/a
• Main Authors: Ding, Shanshan, Hao, Mengmeng, Fu, Changkui, Lin, Tongen, Baktash, Ardeshir, Chen, Peng, He, Dongxu, Zhang, Chengxi, Chen, Weijian, Whittaker, Andrew K., Bai, Yang, Wang, Lianzhou
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.12.2022; John Wiley and Sons Inc; Wiley
• Subjects: Efficiency; Ligands; Morphology; Optical properties; perovskites; photovoltaic performance; proton exchange control; Quantum dots; stability; surface ligands
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202204476

Quantum dots (QDs) of formamidinium lead triiodide (FAPbI3) perovskite hold great potential, outperforming their inorganic counterparts in terms of phase stability and carrier lifetime, for high‐performance solar cells. However, the highly dynamic nature of FAPbI3 QDs, which mainly originates from the proton exchange between oleic acid and oleylamine (OAm) surface ligands, is a key hurdle that impedes the fabrication of high‐efficiency solar cells. To tackle such an issue, here, protonated‐OAm in situ to strengthen the ligand binding at the surface of FAPbI3 QDs, which can effectively suppress the defect formation during QD synthesis and purification processes is selectively introduced. In addition, by forming a halide‐rich surface environment, the ligand density in a broader range for FAPbI3 QDs without compromising their structural integrity, which significantly improves their optoelectronic properties can be modulated. As a result, the power conversion efficiency of FAPbI3 QD solar cells (QDSCs) is enhanced from 7.4% to 13.8%, a record for FAPbI3 QDSCs. Furthermore, the suppressed proton exchange and reduced surface defects in FAPbI3 QDs also enhance the stability of QDSCs, which retain 80% of the initial efficiency upon exposure to ambient air for 3000 hours. An in situ surface ligand regulation strategy for deliberately controlling protonated‐oleylamine (OAm) dominated surface binding of formamidinium lead triiodide quantum dots (FAPbI3 QDs) is demonstrated. The QDs present reduced long‐chain insulating ligand density without compromising their structural integrity, leading to the corresponding QD solar cell a record power conversion efficiency of 13.8% for FAPbI3 QDSCs.