Optical optimization of perovskite solar cell structure for maximum current collection

High conversion efficiency has been recently demonstrated for Perovskite thin film photovoltaic devices. Perovskite thin film solar cells are multilayer opto-electrical structures in which light interference occurs. This phenomenon can be used to maximise the light transmission into the absorber material and increase the device efficiency. Fine tuning of the layer thicknesses within the stack can be used to control interference at the interfaces. Optical reflection losses can be reduced by achieving destructive interference within the structure of the cell. The light transmission to the Perovskite absorber of a thin film solar cell on a fluorine doped tin oxide transparent conductor has been modelled using the transfer matrix method. Alternative transparent conductor materials have been also investigated including AZO and ITO. The modelling showed that replacing FTO with ITO could increase the photocurrent by as much as 4.5%. The gain can be further increased to 6.5% by using AZO as the TCO material. Fine tuning of the TiO2 layer thickness can increase the current density by 0.3%. Furthermore, the current density of a Perovskite solar cell can be increased by application of a multilayer anti-reflective coating by another 3.5%. Optical optimisation of the stack design offers a significant increase in conversion efficiency.