Universal 3D/2D Surface Heterojunction‐Based Piperidine Derivatives for Efficient Inverted Perovskite Solar Cells
Jiafan Zhang, Nan Yan, Yang Cao, Yanyan Li, Renxuan Wang, Danyang Qi, Jiacheng Pi, Nan Li, Xiaolong Feng, Jiarong Wu, Xinyi Liu, Xingyu Gao, Yucheng Liu, Shengzhong Liu, Jiangshan Feng
Abstract
Abstract The 3D/2D perovskite heterostructure has emerged as a promising strategy to simultaneously enhance both the efficiency and stability of perovskite solar cells (PSCs). This work introduced a fluorinated piperidine derivative, 4‐trifluoromethylpiperidine (p‐CF 3 PiP), as a precise surface reconstruction agent for 3D perovskite. By harnessing the strong hydrophobicity of the ─CF 3 groups and the coordination interaction between the piperidine ring and lead iodide, this approach promotes the growth of high‐n‐value ( n = 4) 2D perovskite, resulting in significantly improved film stability. The 3D/2D structure significantly facilitates the extraction and transport of electrons, effectively reducing the density of defect states at the interface, leading to suppressed carrier recombination. The resulting inverted PSC (with a 1.55 eV bandgap) achieved a remarkable power conversion efficiency (PCE) of 26.17%, along with a high open‐circuit voltage ( V OC ) of 1.194 V. This strategy demonstrates broad applicability, as flexible devices reached a PCE of 24.26%, and wide‐bandgap (1.68 eV) systems achieved 22.72%. Notably, the 3D/2D heterojunction exhibits exceptional long‐term stability, maintaining 99% of its initial PCE after 1730 h under ISOS‐L‐1 protocols at 25 °C, and displaying only 20% PCE degradation after 423 h of maximum power point (MPP) tracking under 85 °C.