Light‐Soak Stable Semitransparent and Bifacial Perovskite Solar Cells for Single‐Junction and Tandem Architectures
Mehrdad Najafi, Mirjam Theelen, Henri Fledderus, Dong Zhang, Valerio Zardetto, Bas B. Van Aken, Sjoerd Veenstra
Abstract
Semitransparent perovskite solar cells (ST‐PSCs) are very attractive due to their potential applications in single junctions for building‐integrated photovoltaics (BIPV) and in tandem PV technology using low‐bandgap bottom solar cells. Despite the high efficiency achieved, the ST‐PSCs still suffer low bifaciality, which can limit their overall energy yield for application in BIPV technologies. Furthermore, the knowledge on the long‐term light‐soaking stability of the ST‐PSC from both illumination sides is required to optimize the energy production in the long term. p−i−n ST‐PSCs and semitransparent perovskite solar minimodules with comparable and high efficiencies when illuminated from either the rear or the front sides, resulting in the highest reported bifaciality factor of 97%, are demonstrated. A bifacial equivalent power output of 21.3 W m −2 is achieved for ST‐PSCs under 1 sun illumination on the front side, while using a white back reflector from the rear side with 33.5% reflected albedo. However, the side of illumination has a big impact on the light‐soak stability of the ST‐PSCs. It is observed that the ST‐PSC provides more stable output power under illumination from the rear side (n‐side) of the stack.