Photomechanically accelerated degradation of perovskite solar cells

Abstract

Understanding the origin of intrinsic instability for metal halide perovskites is indispensable for their advancement in opto-electronic applications. Here, we report a photomechanically accelerated degradation mechanism of perovskite thin films, in which the lattice expansion driven by light illumination governs the degradation kinetics. The dynamic lattice evolution under illumination makes the perovskite grains to be crowded with large local strain near grain boundaries (GBs), which facilitates defect formation and iodine-component loss at this region. We show that the physical separation of each perovskite grains using trans-polyisoprene (TPI) can circumvent the photomechanical damage at GBs, and attain T97 of 1000 h under continuous one sun illumination at 55 °C in solar cell devices. The present results emphasize the nontrivial role of dynamic lattice deformation in the decomposition of perovskite thin films, and will open new possibilities to further improve the intrinsic stability of solar cells.