Fabrication Strategy for Efficient 2D/3D Perovskite Solar Cells Enabled by Diffusion Passivation and Strain Compensation
Cuiling Zhang, Shaohang Wu, Leiming Tao, Gowri Manohari Arumugam, Chong Liu, Zhen Wang, Shusheng Zhu, Yuzhao Yang, Jie Lin, Xingyuan Liu, R.E.I. Schropp, Yaohua Mai
Abstract
Abstract Lattice matching and passivation are generally seen as the main beneficial effects in 2D/3D perovskite heterostructured solar cells, but the understanding of the mechanisms involved is still incomplete. In this work, it is shown that 2D/3D heterostructure are unstable under common thermal processing conditions, caused by the lattice expansion of strained 2D perovskite. Therefore an innovative fabrication technology involving a compressively strained PEA 2 PbI 4 layer is proposed to compensate the internal tensile strain and stabilize the 2D/3D heterostructure. Moreover, a small amount of PEA + diffusing into the grain boundaries of 3D perovskite forms 2D perovskite and passivates the defects there. Combining the effects of strain compensation and diffusion passivation, the stabilized 2D/3D perovskite solar cells deliver a reproducible and robust laboratory power conversion efficiency (PCE) of 21.31% for the p‐i‐n type devices, along with a high V OC of 1.18 V. A certified PCE of 20.22% is confirmed by an independent national metrology institute.