Tetraethylenepent-MAPbI_{3- x}Cl_x Unsymmetrical Structure-Enhanced Stability and Power Conversion Efficiency in Perovskite Solar Cells

Two-dimensional (2D) perovskite solar cell (PSC) can achieve high stability by alternating interface cations. However, its main transmissive charge is limited owing to the 2D structure. Therefore, compared with a 3D device, the 2D PSC has poor power conversion efficiency (PCE). Further enhanced performance will require an increase in the transmission dimension of 2D PSC. Here, a novel tetraethylenepent (TEPA)-MAPbI_3-xCl_x analogous 2D unsymmetrical perovskite film was developed to improve the stability and PCE of the corresponding device. Based on the interaction of the active amino linear short chain of TEPA and the halogen ion, the symmetry of the mechanical structure of ions is disrupted, and the TEPA ion is embedded in the perovskite structure to form a perovskite structure with a dimension between 3D and 2D. Noticeably, the TEPA-MAPbI_3-xCl_x devices deliver high PCEs up to 19.73% which stands as the highest for MAPbI_3-xCl_x-based PSC. The environmental, thermal, and illumination stability also showed improvements ranging between 10%-30%. The enhanced PSCs are due to the higher quality of perovskite films, stronger charge transmission, and less trap density. This approach provides a new method to improve and modify 2D PSCs.