Crystallization and composition control of perovskite material for efficient solar/indoor light harvesting and photocatalyst

Abstract

Renewable energy is one of the most efficient solutions for the worldwide concern of energy crisis and global warming. Due to the superior optical and electrical property of lead-halide perovskite materials, it has become promising candidates in multiple applications of renewable energy. Tremendous amount of scientific efforts has been made in both the fundamental research and the application development of perovskite materials, promoting an unprecedented prosperity of this field. Based on the fundamental research of controlling the crystallization and composition of perovskite materials, this dissertation realizes high quality perovskite crystals with specialized properties for efficient solar cells, indoor photovoltaics, and photocatalysts, respectively, aiming for making real impact for the materials or devices to go out of the lab. Although the power conversion efficiency (PCE) of perovskite solar cell (PVSC) has rocketed from 3.8%-2009 to over 25%-2020, the fabrication of high efficiency PVSCs still necessarily relied on the controlled atmosphere, which increases the cost and hinders the real production. Accordingly, a cost-effective and industrial-friendly air-knife assisted recrystallization method was first developed based on sequential deposition to control the crystallization of perovskite in ambient atmosphere. The resulted film shows a strong crystallinity, pure crystal domain, low trap-state density and ideal micrometer-sized single-layer grain morphology, contributing to the record-high ambient-process device performance (> 19.3%) and enhanced stability. The excellent photoelectrical property and adjustable composition also make perovskite a promising candidate for efficiently harvesting indoor light for powering off-grid electronic devices in the upcoming epoch of 5G and Internet of Things (IoTs). A I/Br/Cl triple-anion perovskite material with tailored bandgap and ultra-low trap-state density was strategically developed to efficiently harvest low-density indoor light with special spectrum. The different ionic radius of I/Br/Cl was first reported to induce shrinkage of crystal lattice and restrain halide segregation, thereby beneficial for phase stabilization and device stability. A record-high efficiency of 36.2% was achieved under 1000 lux fluorescent light with excellent long-term stability for over 2000 hours (> 95% PCE), overperforming all the existing indoor photovoltaic cells. In addition, high surface/volume ratio perovskite quantum dot (PQD) with low trap-state density and strong light harvesting ability has a great potential in driving efficient CO2 photoreduction. A self-attaching method was developed with compositional engineering to prepare the bandgap tunable PQDs/polyethersulfone(PES) monolithic film to enhance light harvesting and maximize the specific area, thereby making full use of PQDs in solar-driven CO2 reduction. The small-bandgap I-rich CsPbIxBr3-x PQDs that uniformly distributed on the porous PES scaffold achieves the electron consumption rate of 64.90 μmol g-1 h-1, surpassing all the reported PQD-based photocatalysts in CO2 photoreduction. Our work opens a platform to fully exploit the perovskite nanomaterials and construct three-dimensional nanocatalyst/polymer film for highly efficient photocatalytic reactions. In summary, the crystallization and composition of perovskite materials could be strategically controlled to achieve high performance in multiple renewable energy applications.