Electron‐Selective Strontium Oxide Contact for Crystalline Silicon Solar Cells with High Fill Factor

Abstract

Extensive efforts have been made to develop wide‐bandgap metal compound‐based carrier‐selective contacts to improve the performance of crystalline silicon (c‐Si) solar cells, by mitigating the deleterious effects of metal–Si contact directly. Herein, thermally evaporated wide‐bandgap strontium oxide (SrO x ) is exploited as an electron‐selective contact for c‐Si solar cells. Benefiting from a lower work function (3.1 eV) of SrO x , a strong downward band‐bending is achieved at the n‐type c‐Si/SrO x interface, enabling the electron‐selective transport characteristic. Thin SrO x films simultaneously provide moderate surface passivation after annealing and enable a low contact resistivity on c‐Si surfaces. By the implementation of a single‐dielectric‐layer SrO x ‐based rear contact, a champion power conversion efficiency of 20.0% is realized on the n‐type c‐Si solar cell featuring an intriguing fill factor of 82.8%. Moreover, electron‐selective SrO x contact is demonstrated to show high thermal stability up to 500 °C. The SrO x layer formed by a facile thermal evaporation process presents a unique opportunity to develop highly efficient and low‐cost c‐Si solar cells.