Light‐Soak Stable Semitransparent and Bifacial Perovskite Solar Cells for Single‐Junction and Tandem Architectures

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 BI PV 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 mini-modules 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.