Preparation And Stability Research Of Perovskite Solar Cell

Owing to the simple preparation, low cost and high efficiency of perovskite solar cell, it has become the research focus in the field of photovoltaic device. As an important part of perovskite solar cell, the perovskite film and mesoporous layer have aroused much attention. In this thesis, the perovskite solar cell was optimized fabricated utilizing two-step spin-coating technique, then different kinds of mesoporous TiO₂ was prepared and their impact on cell performance was investigated. Although the efficiency of perovskite solar cell has been continuously improved, the systematic research on the stability of solar cell is insufficient. Herein the stability of solar cell under different environment was explored and the solution in enhancing the stability was proposed.Firstly, the perovskite solar cell was prepared via two-step spin-coating process, and then the preparation technique, optimized technology by pre-film and the humidity during the process were researched systematically. It was found that the cell efficiency was 9.01% with the best morphology of perovskite film when the spin rate was 3k rpm. The introduction of pre-film would contribute to the decrease of residual PbI2 in perovskite film. Especially, when the concentration of precursor was 0.2 M, the efficiency increased to 11.16%. In the case, the morphology of perovskite film got flatter, the light absorption ability enhanced and the recombination rate of carriers decreased. In addition, the coverage of perovskite film and efficiency of solar cell reduced as the humidity in the preparation increased.Secondly, different kinds of mesoporous TiO₂ were synthesized and the performance analysis was conducted by assembled perovskite solar cell. The highest efficiency of solar cell was 9.01% and 5.61% when the porous TiO₂ and TiO₂ nanotube of micron scale were applied respectively. When 0.2 wt% graphene oxide was dipped into porous TiO₂, the efficiency of solar cell increased to 9.97%. The enhancement of device performance can be attributed to the longer electronic life, lower recombination rate and faster electron extraction of TiO₂. The singer layer of TiO₂ hollow sphere was used as the scatting layer to improve the efficiency of light absorption and boosted the efficiency of solar cell to 9.95%.Finally, the stability of uncoated and encapsulated perovskite solar cells was investigated under various environmental conditions. Being exposed to the air with humidity of 5% and 70% for 30 days separately, the efficiency became 65.3% and 16.6% of the initial efficiency value. The weak stability was due to the degradation of perovskite film. When the uncoated cell was set in the environment with 70% humidity and one sun continuous illumination for 10 h, the final efficiency of uncoated cell faded to 19.8% of the initial efficiency value. The main reason was the electronic transmission capacity damage by continuous illumination. When the uncoated cell was placed in the environment with 70% humidity, one sun continuous illumination and high temperature?50 oC? for 2 h, the final efficiency of uncoated cell got 2.2% of the initial efficiency value. High temperature decreased the hole-transmission capability. So the stability of perovskite solar cell was weaker when the environment was more complicated. As for the effect of encapsulation, the stability of cell could be enhanced when the cell was just in moist air, but it was invalid when illumination and high temperature was given.