Simulation of Perovskite Solar Cells: the Role of Internal Interfaces

Abstract

Perovskite solar cells have gathered a large interest in the last years as a very compelling and promising photovoltaic technology thanks to many interesting properties such as a wide spectrum of deposition techniques, a simple integration with both organic and inorganic materials and, most important of all, a high light power conversion efficiency. Perovskite materials have also challenged the scientific community due to the many different physical processes that concur to set the optical and electrical properties: from ferroelectricity [1], to ion migration [2], defects and different recombination processes [3]. An important aspect of perovskite films is the presence of interfaces, both due to grain boundaries as well as due to interfaces between the perovskite layer and the charge selective contacts. Although many progresses have been obtained in the quality of the film, still grain boundaries within the perovskite film in fabricated devices are present. These interfaces can play a major role in setting device performances and hysteresis effects. The effect of these grain boundaries and interfaces have been investigated by many groups, we refer here to just one reference [4], but the effect to free charges and ion migration is still under debate. In the present work we theoretically investigate the effect of ion migration with the presence of grain boundaries. The analysis is performed using two different models: a drift-diffusion model to study the role of the mesoporous electron selective contact [5] and kinetic Monte Carlo [6] for the effect of grains and grain boundaries.