The crystal structure of perovskite is ABX3 type, A represents an organic cation, B represents a metal cation, and X represents a halogen anion. The organic part and the inorganic part respectively determine the ferroelectric and semiconducting properties of the perovskite. Perovskite materials have superior charge transport properties, long carrier diffusion distance, full spectrum absorption and high absorption coefficient. This allows this material to effectively absorb sunlight and efficiently generate photo-generated carriers, while reducing energy loss in the photoelectric conversion process. Therefore, perovskite solar cells (PSC) have high photoelectric conversion efficiency. Due to the bipolar charge transport properties of perovskite, the structure of PSC is also flexible and diverse. The main structure of PSC is mesoporous structure, planar structure, and mesoscopic superstructure. The general structure of PSC contains conductive glass electrodes (FTO, ITO), electron transport layer (ETM), perovskite layer, hole transport layer (HTM) and metal electrodes (Au, Pt, Ag). Its working mechanism is that the perovskite absorption layer absorbs solar photons to generate carriers. Through the energy level matching between the perovskite material and the adjacent two materials, these electrons and holes are separated and effectively collected by the charge transport layer. Holes start from the perovskite layer, pass through the hole transport layer and are finally collected by the metal electrode. On the contrary, electrons start from the perovskite layer and pass through the electron transport layer and are finally collected by the conductive glass electrode. After the perovskite solar cell is connected to an external circuit, a loop can be formed to form an electric current. As a third-generation solar photovoltaic cell, PSC has the advantages of high photoelectric conversion efficiency, flexible preparation, and low cost. It plays an important role in the development of lightweight flexible batteries and household power generation systems.
Figure 1. PSC structure