A Simple Way to Simultaneously Release the Interface Stress and Realize the Inner Encapsulation for Highly Efficient and Stable Perovskite Solar Cells. (30th September 2019) - Wu, Jionghua
Abstract: The mixed halide perovskites have become famous for their outstanding photoelectric conversion efficiency among new‐generation solar cells. Unfortunately, for perovskites, little effort is focused on stress engineering, which should be emphasized for highly efficient solar cells like GaAs. Herein, polystyrene (PS) is introduced into the perovskite solar cells as the buffer layer between the SnO2 and perovskite, which can release the residual stress in the perovskite during annealing because of its low glass transition temperature. The stress‐free perovskite has less recombination, larger lattices, and a lower ion migration tendency, which significantly improves the cell's efficiency and device stability. Furthermore, the so‐called inner‐encapsulated perovskite solar cells are fabricated with another PS capping layer on the top of perovskite. As high as a 21.89% photoelectric conversion efficiency (PCE) with a steady‐state PCE of 21.5% is achieved, suggesting that the stress‐free cell can retain almost 97% of its initial efficiency after 5 days of "day cycle" stability testing. Abstract : The polystyrene is introduced into perovskite solar cells as the buffer layer between the SnO2 and perovskite, which can release the stress during the perovskite annealing. A large lattice, fewer defect, and low ion‐immigration‐energy perovskite can be obtained by releasing stress. Finally, 21.89% efficiency is obtained and the cell can maintain almost 97% of the initial efficiency after 5 days.