Traditional oxide perovskites are usually dielectric materials. The advent of halide perovskites for photovoltaic applications, however, has opened new avenues for research on perovskite materials. The rapid increase in power conversion efficiency of perovskite-based solar cells, added to their low-cost solution-based processing, has led to active research aiming for industry penetration. In parallel to these developments for photovoltaics, other promising applications in light-emitting diodes, semiconductor lasers, and photodetectors are also quickly emerging. It is evident that perovskites have opened the door of using non-traditional semiconductors for mainstream applications, which are currently dominated by group-IV, III-V, and II-VI semiconductors.
As revealed over the past several years, novel physical properties of the hybrid halide perovskites are behind the achievements of these materials. For example, these materials exhibit high defect tolerance so that defect-mediated non-radiative recombination is weaker than radiative recombination. According to recent reports, even the radiative recombination could be significantly reduced by screening effect due to the nearly freely rotating dipolar cations. Understanding such new physics is not only essential to the further development of these materials for applications, but also enriches our knowledge base of semiconductor physics. It is also worthwhile to explore the extent to which the unique physics of the hybrid halide perovskites is still valid in other perovskite and related materials, such as non-halide perovskites, double and Ruddlesden-Popper perovskites, etc. Achieving this goal requires synergetic efforts from synthesis of high-quality materials, delicate characterization of their properties, as well as understanding of the physical processes from theory and computation. This symposium will be dedicated to understanding perovskite semiconductors from their fundamental physics and materials science aspects.