Perovskite Films with Reduced Interfacial Strains via a Molecular-Level Flexible Interlayer for Photovoltiac Application
Cong-Cong Zhang,1,3 Shuai Yuan,1 Yan-Hui Lou,2 Qing-Wei Liu,1 MengLi,1 Hiroyuki Okada3 and Zhao-Kui Wang1,*
1Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, China.
2School of Energy, Soochow Institute for Energy and Materials Innovations and Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China.
3Graduate School of Science and Engineering University of Toyama, Toyama 930-8555, Japan
Interface strains and lattice distortion are inevitable issues during perovskite crystallization. Silane as a coupling agent is a popular connector to enhance the compatibility between inorganic and organic materials in semiconductor devices. Herein, a protonated amine silane coupling agent (PASCA-Br) interlayer between TiO2 and perovskite layers is adopted to directionally grasp both of them by forming the structural component of a lattice unit. The pillowy alkyl ammonium bromide terminals at the upper side of the interlayer provide well-matched growth sites for the perovskite, leading to mitigated interface strain and ensuing lattice distortion; meanwhile, its superior chemical compatibility presents an ideal effect on healing the undercoordinated Pb atoms and halogen vacancies of bare perovskite crystals. The PASCA-Br interlayer also serves as a mechanical buffer layer, inducing less cracked perovskite film when bending. The developed molecular-level flexible interlayer provides a promising interfacial engineering for perovskite solar cells and their flexible application.