Working Principles of Perovskite Solar Cells

This chapter examines the updated knowledge on the working mechanisms of perovskite solar cells, with the focus on physical processes determining the photovoltaic performance. This includes charge generation, charge transport, charge carrier losses through recombination, and charge extraction. The chapter also examines the main parameters defining those processes and discusses the ionic nature of metal halide perovskites, as well as its implications in the processes and unconventional phenomena of the solar cells. The unique properties of perovskites, such as fast exciton dissociation and large diffusion lengths, together with the shallow trap states caused by impurities, reduces to a large extent the charge carrier loss within the perovskite bulk. The initial evolution of perovskite solar cells relied on the charge extracting materials employed. The progress on perovskite solar cell has been characterized by fast and unexpected device performance improvements, but these have usually been driven by material or processing innovations.