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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 (SrOx) is exploited as an electron‐selective contact for c‐Si solar cells. Benefiting from a lower work function (3.1 eV) of SrOx, a strong downward band‐bending is achieved at the n‐type c‐Si/SrOx interface, enabling the electron‐selective transport characteristic. Thin SrOx 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 SrOx‐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 SrOx contact is demonstrated to show high thermal stability up to 500 °C. The SrOx layer formed by a facile thermal evaporation process presents a unique opportunity to develop highly efficient and low‐cost c‐Si solar cells. [ABSTRACT FROM AUTHOR]

In non‐fullerene‐based photovoltaic devices, it is unclear how excitons efficiently dissociate into charge carriers under small driving force. Here, we developed a modified method to estimate dielectric constants of PM6 donor and non‐fullerene acceptors. Surprisingly, most non‐fullerene acceptors and blend films showed higher dielectric constants. Moreover, they exhibited larger dielectric constants differences at the optical frequency. These results are likely bound to reduced exciton binding energy and bimolecular recombination. Besides, the overlap between the emission spectrum of donor and absorption spectra of non‐fullerene acceptors allowed the energy transfer from donor to acceptors. Hence, based on the synergistic effect of dielectric property and energy transfer resulting in efficient charge separation, our finding paves an alternative path to elucidate the physical working mechanism in non‐fullerene‐based photovoltaic devices. [ABSTRACT FROM AUTHOR]