Method for improving illumination instability of organic-inorganic halide perovskite solar cells

Organohalogen perovskites are attracting considerable attention for use in solar cells. However, the stability of these devices will determine whether they can be made commercially viable. Device encapsulation or the use of a hydrophobic hole-transporting material can prevent the permeation of water into the perovskite layer and enhance the humidity stability of the cells under dark conditions. With regard to the light stability of solar cells, recent studies have yielded contradictory results. This work investigated the degradation mechanism of perovskite solar cells under illumination. Further, a simple method was proposed for improving their illumination stability. Amino acids were inserted between the compact TiO2 layer and the perovskite layer to effectively prevent the decomposition of the perovskite layer owing to the superoxide anions and hydroxyl radicals generated under illumination from the H2O and O-2 adsorbed onto the TiO2 layer.