Hole Selectivity of n‐Type Molybdenum Oxide Carrier Selective Layer for Commercial and Emerging Thin‐Film Photovoltaics: A Critical Analysis of Interface Energetics and Ensuant Device Physics

Energetics at the carrier selective layer/absorber interface plays a subtle, yet crucial role in influencing the performance of any photovoltaic technology. This review focuses on the interface energetics and resulting aspects of device physics associated with n‐type molybdenum oxide, which is adopted as a hole selective layer over a diverse class of photovoltaic technologies ranging from silicon heterojunction, organic, and perovskite solar cells. As existing literatures provide a very inconsistent picture of the electronic structure of transition metal oxides, specifically in the case of molybdenum oxide (MoO x ), this review makes a first‐of‐its‐kind attempt to connect the scattered reports and thus highlight the ways in which device performance varies for a diverse class of photon absorbers used in conjunction with n‐type MoO x hole selective layer. In spite of the interfacial energy requirements and in turn fundamental working mechanism of varied photovoltaic technologies being the same, an attempt to compare and collate the contributions of MoO x as a charge selective layer for each of these technologies is yet to be done. Herein, the role played by MoO x /absorber interface engineering on the performance of varied photovoltaic technologies, which remains a fundamental and yet unaddressed theme till date, is focused on.