(Invited) Efficient and Stable Perovskite Solar Cells Enabled By Surface Engineering with Bulky Organic Molecules

Abstract

Organic-inorganic hybrid halide perovskites have attracted significant R&D attention in the photovoltaic (PV) community as a competitive technology for future PV applications. The certified efficiency of single-junction perovskite solar cell (PSC) has reached close to 26%. Using molecules/structures based on bulky organic cations (e.g., butylammonium or phenethylammonium) to improve the surface/interface properties has become a promising strategy to enhance PSC performance, including both efficiency and stability. However, significant issues still exist with the use of bulky organic molecules, such as structure control, charge transport, bulk and surface morphology, and interfacial energy alignment. In this talk, I will discuss our recent studies on surface engineering of 3D perovskites by using structures based on bulky organic molecules. The use of bulky organic molecules often results in the formation of 2D perovskite structures, which usually exhibit significant transport barriers, especially in the out-of-plane transport direction. In addition, the use of bulky organic structures can interrupt the growth of 3D perovskites. A good understanding and control of perovskite growth is critical to fully utilize the benefits associated with bulky organic molecules and related structures. I will present strategies for suppressing defect formation, improving bulk and surface morphology, and reducing transport barrier for better extraction. The physical and optoelectronic properties of perovskites can be affected by controlling the precursor chemistry and growth conditions. Some of our recent results on perovskite-based tandem devices will also be discussed. Finally, I will discuss our recent progress on selecting stability protocols to accelerate the development process of PSCs toward future commercialization.