Oriented wide-bandgap perovskites for monolithic silicon-based tandems with over 1000 hours operational stability
Yuxin Yao, Biao Li, Degong Ding, Chenxia Kan, Pengjie Hang, Daoyong Zhang, Zechen Hu, Zhenyi Ni, Xuegong Yu, Deren Yang
Abstract
The instability of hybrid wide-bandgap (WBG) perovskite materials (with bandgap larger than 1.68 eV) still stands out as a major constraint for the commercialization of perovskite/silicon tandem photovoltaics, yet its correlation with the facet properties of WBG perovskites has not been revealed. Herein, we combine experiments and theoretical calculations to comprehensively understand the facet-dependent instability of WBG perovskites. We find that the (111) facet, which owned higher ion-migration activation energy and lower diffusion constant, endured instability better than the (100) facet in multi-component 1.68 eV perovskites under electron beam or light irradiations, where excess charge carriers facilitate halide migrations and thereafter phase segregations. By introducing trioctylphosphine oxide into the WBG perovskite, a strong oriented growth of the (111) facet for the WBG perovskite film was realized which exhibited enhanced operational stability against light illumination. The fabricated one square centimeter area perovskite/silicon tandems with n-i-p and p-i-n configurations deliver efficiencies of 28.03 % and 30.78 % (certified 30.26 %), respectively, with both configurations exhibiting excellent operational stability at the maximum power point (MPP) with T95 > 1000 h. The correlation between the instability and facet properties of wide-bandgap perovskites has not been revealed. Here, the authors introduce trioctylphosphine oxide for strong oriented growth of (111) facet in films and achieve certified efficiency of 30.26% for perovskite/silicon tandem solar cells.