Intermediate-States Mediated 2D MoO3-x Plasmon Enabling Pure-Phased CsPbX3 Photovoltaics with 27.33% Bifacial Efficiency.

All-inorganic CsPbX3 (X = I, Br, Cl) perovskites emerged as a crucial material for addressing the stability bottleneck due to their exceptional resistance to both light-thermal stress. However, their performance is limited by adverse optoelectronic dissipation arising from inadequate photon conversion and chaotic carrier energetics. Herein, the mechanism of the unique nonlinear plasmonic effect in van der Waals 2D MoO3-x is elucidated, which is mediated by electronic intermediate states. It demonstrates that the 2D MoO3-x serves as a light-capture-antenna in heterodimensional CsPbX3-MoO3-x optically coupled system, contributing to the accumulation the optical field energy on the nanoscale and resulting in a remarkable 59% increase in photon convergence. Additionally, facet-oriented carrier channels can be established through heteroepitaxy along matched Mo-O octahedron. This optoelectrical-bimodal-coupling engineering combined with a bifacial light-harvesting configuration yields a bifacial equivalent efficiency of 27.33%, which stands as the supreme performance in all-inorganic perovskite photovoltaics.