A review on computational modelling of individual device components and interfaces of perovskite solar cells using DFT

Perovskite structures with the same crystal structure as CaTiO3, are of importance in the field of Materials Science right from the discovery of ceramic high-temperature superconductors to the organic–inorganic semiconductors for high-efficiency photovoltaics. Owing to their unique crystal structure, perovskites display a variety of interesting properties like ferroelectricity, superconductivity, magnetoresistance, birefringence, piezoelectricity etc. Moreover, the efficiency of perovskite solar cells has increased from 3.1% in 2009 to 22.1% in 2017. Since a large number of elements can be combined to form perovskite structures, one can selectively design and optimize perovskite’s physical, optical and electrical characteristics. Through theoretical and computational modelling, it is possible to access the hitherto unknown atomistic properties, opto-electronic properties and operational mechanisms of these materials with high accuracy. This paper aims at explaining some of the potentialities of DFT hybrid functionals to analyze the electronic, structural and optical properties of compounds constituting various layers of a perovskite solar cell with the help of software packages like VASP, Wien 2k. Gaussian 09 etc. This paper also reviews the effect of doping on the electronic properties of various layers of perovskite solar cells including the band gap, visible light absorption, relaxation time of holes and electrons using DFT, which in turn determines the optimum charge separation. The effect of introduction of an Intermediate Band Gap in the perovskite structure using DFT methods based on G0W0+SOC approach is also discussed here. A study on the effect of various intrinsic defects present in perovskite structures using DFT calculations with VASP package is also discussed. The relevance of modelling the interfaces of various layers of perovskite solar cells with DFT packages is discussed with the help of selected examples of materials and representative interfaces.