Minimizing interfacial energy losses via multifunctional cage-like diammonium molecules for efficient perovskite/silicon tandem solar cells
Xin Li, Zhiqin Ying, Linhui Liu, Jun Wu, Hongwei Ma, Ziyu He, Yunyun Yu, Yihan Sun, Meili Zhang, Xuchao Guo, Yuheng Zeng, Xi Yang, Jichun Ye
Abstract
Abstract Wide bandgap (WBG) perovskites hold tremendous potential for enabling efficient perovskite/silicon tandem solar cells. However, interfacial energy losses at the perovskite/electron selective contact interface remain a substantial obstacle in approaching its theoretical efficiency limit. Herein, for the first time, a multifunctional cage-like diammonium chloride molecule, featuring Lewis acid/base groups and strong molecular polarity, is designed to reduce film defects and modulate the interfacial dipole, thereby suppressing non-radiative recombination and optimizing surface band alignment. More importantly, the unique cage-like cation can induce the formation of a phase-pure quasi-2D perovskite with spontaneous in-plane orientation and exhibits a pronounced ferroelectric effect, facilitating carrier further apart and extraction by upshifting the surface work function. Consequently, we achieve 1.68 eV perovskite solar cells with power conversion efficiencies (PCEs) of 22.6% (0.1 cm 2 ) and 21.0% (1.21 cm 2 ). Furthermore, two-terminal monolithic perovskite/silicon tandem solar cells based on tunnel oxide passivating contact yield an impressive PCE of 31.1% (1.0 cm 2 ) and demonstrate a decent operational stability (ISOS-L-1, T 85 > 1020 h in ambient conditions without encapsulation). The ferroelectric interface physics opens new possibilities for efficient and stable perovskite-based tandem photovoltaics.