The stability of perovskite solar cells

Abstract

Solar energy as a widespread clean energy is considered to be the key to solving future energy problems, solar cell technology is also evolving, of which perovskite solar cells because of its rapid growth efficiency gains wide attention. The great breakthroughs have been observed in organic-inorganic halide perovskite solar cells. However, the long-term stability due to decomposition and the toxicity of heavy metal lead have not been perfectly solved. Solving the stability problem will be the key to the future application of perovskite solar cells. This review focuses the factors affecting the stability of perovskite solar cells from the perspective of perovskite solar cell structure, including perovskite materials, hole transport materials, electron transport materials, and electrodes. Through the analysis we found that for perovskite materials, grain size and defect density affect the stability of perovskite. The grain with large size will inhibit the defect state, improve the stability of the device. Moisture, oxygen and light will promote the decomposition process of perovskite, even in the case of isolated air. The thermal stability of perovskite is also poor and will be self-decomposition at a certain temperature. While perovskite will also have the problem of crystal structure instability, the perovskite may changes to the non-perovskite phase, which will result in a sharp attenuation of efficiency. The dopant in the hole transport material may cause destruction and decomposition of the perovskite structure. The titanium dioxide commonly used in electron transport materials can lead to the decomposition of perovskite and the reduction of electron transport efficiency due to oxygen vacancy and strong electron extraction. Silver and aluminum commonly used in electrode will be associated with the perovskite layer formation of halide, which may reduce the conductivity of the electrode and destroy the perovskite structure. In order to solve the above problems, we propose that new preparation should be developed to get thin films with large grain size. The researchers also should find new perovskite material insensitive to moisture and oxygen, appropriate package to isolate the air from the water and oxygen. The inorganic perovskite materials with enhancing thermal stability of the perovskite film should be considered to improve the stability of perovskite solar cells. Developing organic hole transport materials that do not require additives or inorganic hole transport materials can reduce the possibility of perovskite crystals being destroyed by hole transport materials. Avoid direct contact between perovskite and titanium dioxide or use other electron transport materials instead of titanium dioxide to prevent the decomposition of perovskite. Furthermore, we recommend mesoscopic framework based on all inorganic metal oxides for organic-inorganic perovskite based photoelectric conversion devices.