Conductive passivating contact for high fill factor monolithic perovskite/silicon tandem solar cells

Abstract

Perovskite/silicon tandem solar cells (PK/Si TSCs) blaze the way in pushing power conversion efficiency (PCE) beyond the single-junction Shockley–Queisser limit. Meanwhile, localized defects in perovskite subcells result in a lower fill factor (FF), which limits further improvement of PCE in PK/Si TSCs. Herein, we report a conductive passivation contact layer by posttreatment of bis(2-hydroxyethyl)dimethylammonium chloride (BDAC) zwitterion molecule on the perovskite surface. It can passivate the positive and negative localized defects, inhibit the formation of Pb0, and spontaneously convert the perovskite surface to be a more n-type conductive contact layer for charge separation. These combined enhancements enabled a PCE of 21.4% with an enhanced VOC of 80 mV and an FF of 82.84% for the inverted single-junction device prepared by the two-step method. Moreover, BDAC passivation achieved a PCE of 28.67% with an FF of 80.02% for PK/Si TSCs. In addition, the scaling-up device with an active area of 11.879 cm2 delivers a PCE of 24.46%, and a minimodule with power conversion over 2 W is designed and fabricated.