The role of hydrophobic molecules in the optoelectronical attributes of triple-cation perovskite solar cells

Abstract

The partial modification of perovskite cations has already been done to stabilize perovskite solar cells (PSCs). In this study, Cs/FA/MA triple-cation (3D) perovskite and PTA2PbI4 (2D)/3D perovskite were used as light-absorbing materials in PSCs. Phenyl trimethylammonium iodide (PTAI) was also used as a passivator. It was found that PTAI can serve as an original PTA two-dimensional (2D) cation and as a basis for the formation of 2D/3D heterostructure films. Since an improper post-annealing temperature leads to the uncontrollable degradation of 3D perovskites, this study examines post-annealing at various temperatures to make a 2D perovskite film on a 3D perovskite layer. The proper post-annealing temperature to make a 2D/3D structure was 150 °C exerted for five minutes. Through PTAI post-treatment in these optimum conditions, the morphology of the perovskite layer was improved, which confirms the facilitation of the charge transfer. Indeed, a 2D/3D heterostructure originating from a PTAI solution serves as a film to protect perovskite layer from destruction and improves charge transfer. Therefore, the treatment of perovskite layers, as practiced in this study, can enhances the stability and the efficiency of hole-transport-free PSCs and predispose their industrial production. The efficiency of the optimized device was enhanced for 35 % in comparison to the control samples. The device could also maintain 90 % of its PCE for 177 days.