CHAPTER 4: Solution-processed Solar Cells: Perovskite Solar Cells

Solar cells based on monovalent alkali or organic A-cation, divalent metal B-cation and monovalent halide anion (ABX₃) perovskite semiconductors are emerging as a fast-growing research area with substantial technological potential. Discovered as an absorber in dye-sensitised solar cells, a range of processing strategies developed for printed organic photovoltaics have been used to deposit ABX₃ solar cells from solutions. ABX₃ semiconductors have comparable optoelectronic properties to GaAs and so far are the best solution-processed solar cell technology for small-area test devices. As device performances are comparable with other thin-film solar cell technologies, ABX₃-based solar cells are reaching the phase of being evaluated for their potential in large-scale use for solar energy conversion. This chapter highlights the technological potential arising from the solution-processability of ABX₃ materials. Recent insights into how ABX₃ solution chemistry and lead–halide–solvent structural intermediates during film formation define the thin-film morphology of solution-processed ABX₃ devices are discussed. Gaining control over film formation is a prerequisite to achieve further progress in scaling ABX₃ devices to larger areas with solution-based processing methods. Apart from developing scalable process technology, rationalising material degradation pathways is of paramount importance, to make reliable predictions of device stability. Concerns regarding the potential ecotoxicity of lead-based materials has inspired the search for the next generation of ABX₃-derived materials with similar favourable optoelectronic properties such as their solution-processability and defect tolerance.