A research team, led by Prof. Zhou Huiqiong's group from the National Center for Nanoscience and Technology (NCSNT) of the Chinese Academy of Sciences (CAS), has developed a strain relaxation strategy to study the effect of residual strain on properties of quasi-two-dimensional (2D) perovskites.
The introduction of hydrophobic spacer cations makes quasi-2D perovskites more stable compared with traditional 3D perovskites, but the stability of perovskites remains unsatisfactory. Residual strain is closely related to the crystallographic properties, which in turn can significantly affect the photovoltaic properties and stability of perovskites. The research team investigated the residual strain in quasi-2D perovskite with mixed spacer cations by X-ray diffraction (XRD) and atomic force microscope (AFM). They found that there is severe tensile strain along the out-of-plane direction in pristine perovskite film, leading to poor crystallinity and insufficient stability issues. With an appropriate composition of spacer cations, the tensile strain is effectively released.
The team believes that optimizing the spacer cations could regulate the residual strain in quasi-2D perovskite, further improving the intrinsic stability of perovskites. This work provides a feasible strategy for regulating the photovoltaic properties and improving the stability of perovskite-based photovoltaic devices.