Can R2BX4/ABX3 Heterostructures Harmonise Stability and Efficiency in Perovskite Photovoltaics? A Minireview

Halide perovskites are one of the most extensively explored materials for photovoltaics and their photo-conversion efficiency has reached over 25%. 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 which 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 perovskite coincides with a bulk of 3D perovskites. The compositional development, structural variations, and controlling the level of 2D doping in this kind of perovskites have been discussed. Moreover, film quality, photophysics, photovoltaic performance and stability of such heterostructures were also discussed. Finally, our efforts aimed to offer a glimpse into the potential future applications of R2BX4/ABX3 in improving perovskite photovoltaics and other applications beyond solar cells.