Can R2BX4/ABX3 Heterostructures Harmonize the Stability and Efficiency of 2D/3D Perovskite Photovoltaics? A Minireview

Halide perovskites are one of the most extensively explored materials for photovoltaics, and their photoconversion efficiency has reached over 26%. Three-dimensional (3D) perovskites have exceptional optoelectronic properties but suffer from poor stability, hindering their commercialization. Contrarily, two-dimensional (2D) perovskites offer excellent stability but inferior optoelectronic performance. The structural flexibility of perovskites allows the researcher to fabricate 2D/3D mixed dimensional perovskites that exhibit superior stability without compromising the efficiency. Herein, we have explored the available literature on a distinct category of 2D/3D perovskites, R₂BX₄/ABX₃ type mixed phase heterostructures. In such heterostructures, a minor quantity of phase pure 2D perovskites coincides with a bulk of 3D perovskites. The compositional development, structural variations, and controlling the level of 2D doping in this kind of perovskite are discussed. Moreover, film quality, photophysics, photovoltaic performance, and stability of such heterostructures are also discussed. Finally, our efforts aim to offer a glimpse into the potential future applications of R₂BX₄/ABX₃ in improving perovskite photovoltaics and other applications beyond solar cells.