Device Physics and Design Principles of Mixed-Dimensional Heterojunction Perovskite Solar Cells

Mixed-dimensional perovskites possess unique photoelectric properties and are widely used in perovskite solar cells (PSCs) to improve their efficiency and stability. However, there is a pressing need for a deeper understanding of the physical mechanisms and design principles of mixed-dimensional PSCs, as such knowledge gaps impose restrictions on unlocking the full potential of this kind of PSC. Herein, a 2D/3D PSC is employed as an example to clarify the working mechanism of mixed-dimensional PSCs from the perspective of device physics and elaborate on the design rules of high-efficiency mixed-dimensional PSCs. Detailed simulation results indicate that the insertion of a layer of 2D perovskite between the 3D perovskite and the hole transport layer (HTL) can significantly reduce the recombination at the HTL/perovskite interface, and PSCs with a 2D/3D perovskite structure exhibit higher tolerance to material selectivity compared with their 3D counterparts. Additionally, the 2D/3D perovskite design can slow down ion migration and accumulation processes, thereby easing the hysteresis behavior of 2D/3D PSCs. Moreover, it is also found that the 2D/3D perovskite structure has a more pronounced effect on improving the efficiency of wide-bandgap PSCs. Overall, this work sheds new light on mixed-dimensional PSCs, enabling better guidance for designing high-efficiency PSCs.