(Invited) Rational Strategies for Efficient Perovskite Solar Cells

Abstract

The past decade has witnessed tremendous advances in organometal halide perovskite solar cells (PSCs) due largely to the stellar set of optoelectronic properties of perovskites such as high absorption coefficient, long carrier diffusion length, and low electron–hole recombination rate constant. Notably, the organolead halide PSC has reached a certified champion power conversion efficiency (PCE) of 25.2%. Rapid progress in PCE has been realized by structure design, materials chemistry, process engineering, and device physics. In this talk, I will first introduce a meniscus-assisted solution printing method (MASP) towards large-grained perovskite films for morphology and crystallinity control. Intriguingly, the outward convective flow triggered by fast solvent evaporation at the edge of the meniscus ink imparted the diffusion of perovskite solutes, thus facilitating the growth of micrometer-scale perovskite grains, leading to perovskite film with good crystallization and preferred orientation. This robust MASP strategy may in principle be easily extended to craft other solution-printed perovskite-based optoelectronics. Secondly, I will demonstrate an interesting interface engineering approach with 2D ambipolar black phosphorene (BP) for high-efficiency and stable PSCs. BP carries a stellar set of physical properties such as conveniently tunable bandgap and extremely high ambipolar carrier mobility. Concurrently enhanced carrier extraction at both electron transport layer/perovskite and perovskite/hole transport layer interfaces was achieved through judicious design and position of BP with tailored thickness as dual-functional nanomaterials. Thirdly, a spatial poling approach will be introduced for perovskite recrystallization towards preferred orientation, crystallinity, and morphology. Finally, the challenges facing the future development and commercialization of PSCs will be summarized and provided.