Stability of Hybrid Perovskites for Tandem Solar Cells
Hybrid metal halide perovskites have emerged as an important new class of materials for photovoltaics. Their integration in tandem with other photovoltaic technologies such as silicon cells is highly desirable, allowing low-cost cells with efficiencies in excess of the Shockley-Queisser single-junction limit. Optimized photocurrent matching between top and bottom cells requires careful control over band-gap energy of the perovskite for which the development of stable, compositionally tuneable perovskites will be essential. In this project, we will explore emerging hybrid perovskites with a focus on developing our fundamental understanding of how structural properties in these relatively “soft” semiconductors are related to their thermodynamic stability and optoelectronic properties. The project will be based around a multi-facetted experimental investigation, involving structural probes e.g. through X-ray diffraction, and transient charge-carrier probes using THz conductivity and photoluminescence spectroscopy. Using these measurements, we will establish links between structural and electronic properties, which will allow us to reveal e.g. the mechanisms behind light- and electric-field-induced changes in these materials, and the causes of miscibility gaps. We will exploit the resulting insight to develop new perovskite compositions and material processing protocols to create thin-film perovskite absorbers with long-term stability for tandem solar cells.