Efficiency limits of Perovskite Solar Cells with Transition Metal Oxides as Hole Transport Layers

Transition metal oxides (TMOs) like MoOx are increasingly explored as hole transport layers for perovskite-based solar cells. Due to their large work function, the hole collection mechanism of such solar cells are fundamentally different from other materials like PEDOT: PSS, and the associated device optimizations are not well elucidated. In addition, the prospects of such architectures against the challenges posed by ion migration are yet to be explored - which we critically examine in this contribution through detailed numerical simulations. Curiously, we find that, for similar ion densities and interface recombination velocities, ion migration is more detrimental for Perovskite solar cells with TMO contact layers with much lower achievable efficiency limits (21%). The insights shared by this work should be of broad interest to the community in terms of long-term stability, efficiency degradation and hence could help critically evaluate the promises and prospects of TMOs as hole contact layers for perovskite solar cells.