Second generation solar cells based on thin films of polycrystalline semiconductors promise to reduce the cost of sunlight-to-electricity conversion compared to first generation crystalline silicon. Efficient thin-film absorber materials can fulfil the multiple roles of light-absorption, charge separation, and transport of both holes and electrons out of the device. A third generation of materials, which can be processed with solution-based techniques at low-temperature, such as printing, should ultimately lead to the least expensive solar cell technology. However, most of the materials processable with the lowest cost methods usually require complex architectures of distributed heterojunctions to ionise tightly bound electron-hole pairs. This inherently introduces losses at the high density of internal material interfaces. Recently organic-inorganic metal halide perovskite absorbers have rocketed to the forefront of PV research as efficient solar cell materials, which seem to be both simple to process and promise to reach the highest efficiencies. This paradigm shift arguably represents a 4th generation of photovoltaics.
Here I will present our developments in perovskite solar cells, highlighting how the technology has mutated and evolved from a nanostructured solar cell to a thin film device. I will present our recent results on improving and understanding perovskite solar cells, with both device based and spectroscopic investigations and highlight some of the reasons why these materials work so well and the future prospects.