Improved morphology, structure and optical properties of CH3NH3PbI3 film via HQ additive in PbI2 precursor solution for efficient and stable mesoporous perovskite solar cells

Abstract

The hybrid halide perovskite is a promising material among next-generation photovoltaic devices due to its high absorption coefficient, low-cost raw materials, and facile film and device fabrication. However, due to the nature of solution processing and lack of precise control over the crystallization of perovskite thin films, a variety of defects, for example, pinholes and grain boundaries can form as a result of the processing conditions that decrease their efficiency and stability. Further, controlling the surface morphology, grain size, charge recombination and optical properties in the perovskite layer is critical to enhancing the photovoltaic performance and stability of solar cells. Here, we mainly focus on a simple and effective method for crystal growth and defect passivation via additive engineering in CH3NH3PbI3 perovskite films were prepared by a two-step deposition process. For this purpose, we introduce the incorporation of hydroxyquinoline (HQ), as one of the Lewis bases with coordinating capability, into the perovskite precursor solution to control nucleation, crystal growth, and optical properties of prepared perovskite films. The results show that HQ additive has a good strategy to improve the perovskite film for perovskite solar cells (PSCs) applications. As a result, we realized stable and efficient mesoporous PSCs, prepared with 0.3 wt% HQ additive, with excellent reproducibility achieving a champion efficiency of 16.33%, higher than that of the pristine one (12.35%) and the ambient condition stability of devices retain 80% of the initial values after 30 days of storage, which is higher than that of pristine PSCs without HQ additive (25%).