Engineering perovskite crystalization kinetics for high-efficiency and stability perovskite solar cells

Abstract

Researchers have recently paid close attention to the perovskite thin film technology because of its rapid growth in power conversion efficiency (PCE) over a relatively short time. A highly advanced photovoltaic material called perovskite, used in solar cells, can absorb sunlight and instantly transform it into electricity. This method is ideal for producing energy using ubiquitous solar power since it is environmentally friendly and renewable. Perovskite solar cells (PSCs) must have excellent stability, exceptional photovoltaic performance, and affordable large-area devices to be industrialized. Many studies have been conducted on the film-coating process for PSC production. In the mainstream one-step method, researchers have realized the formation of the intermediate phase of the perovskite complex in conjunction with antisolvent drop-casting, often followed by annealing to convert it into high-quality perovskite film. Due to its restrictions on substrate size, the lab spin-coating process only successfully covers limited, flat surfaces, making it unsuitable for large-scale manufacturing. Even though additive engineering in perovskite precursors has a solid track record in spin-coated PSCs, more thorough research into coating-friendly multifunctional additives that are specially designed for scalable deposition of perovskite films to improve PSC performance is still lacking. The stability issue is the main obstacle in the commercialization of PSCs due to the delicate and ionic nature of halide perovskite materials. Intrinsic defects at the perovskite surface and grain boundaries, which can negatively impact device performance, can hasten perovskite breakdown. In my PhD research, I have conducted the following research projects on addressing some of the important challenges in the PSC field. I first integrated a multifunctional zwitterionic surfactant into perovskite ink to facilitate room-temperature meniscus coating of superior perovskite films. The inclusion of the surfactant into the ink provides many benefits for film development, including enhanced crystallization kinetics, defect passivation, and protection against moisture barrier weakness. Then, we created a quick and efficient green solvent engineering (GSE) approach to use green ethyl alcohol (EtOH) instead of the conventional harmful solvent. With the aid of this technology, it is possible to create high-performance room-temperature blade-coated PSCs and modules while minimizing risks to the environment and health. In the third project, my research focuses on addressing the PSC stability issue with a new cross-linking strategy. Specifically, a novel cross-linking initiator divinyl sulfone (DVS), is incorporated into the perovskite precursor solution and achieves high-quality perovskite films with low defect density and high stability. This DVS successfully replaces benchmark DMSO, and furthermore, made it possible for a controlled co-polymerization to occur both at the perovskite surface and in the GBs, ensuring a balanced kinetics for the formation of perovskite crystals by modifying the intermediate-dominated perovskite crystallization and passivating the intrinsic defects at the near-surface region.