Recently, the research group of Associate Professor Zhang Taiyang and Professor Li Xiangqing from the School of Chemical and Environmental Engineering of SIT has made important progress in the research field of hole-free transport layer perovskite solar cells based on carbon electrodes, and the relevant results were published in the top journal of chemistry Angew.Chem.Int.Ed. The first author of the paper is Huang Guopeng, a graduate student in Grade 2022 of the School of Chemical and Environmental Engineering. Associate Professor Zhang Taiyang and Professor Li Xiangqing are the corresponding authors of the paper, and SIT is the only communication unit.
Perovskite solar cells have the advantages of mild manufacturing conditions and high photoelectric conversion efficiency, which is the most potential technology in the new generation of photovoltaic technology. High efficiency perovskite solar cells usually use precious metals such as gold and silver as electrodes, which have a higher cost and react with halogen ions diffused in perovskite, limiting long-term stability. The use of chemically stable carbon electrodes instead of conventional precious metal electrodes can further reduce the manufacturing cost of perovskite solar energy while significantly improving the stability of the device. The carbon electrode can be prepared into a carbon film independently of perovskite and then layered onto the perovskite film, further simplifying the process flow of solar cell devices and providing a richer choice for product pipeline process design.
The surface roughness of the carbon film is huge, and its plasticity is poor. When the carbon film is laminated to the smooth surface of perovskite, it is difficult to form a dense and conformal interface contact, resulting in the accumulation of charge carriers at the interface and the holes at the interface also become channels for water intrusion, which reduces the performance of the device. The above factors cause that the device efficiency of the hole-free transfer layer carbon electrode battery prepared based on the carbon film lamination strategy is much lower than other carbon electrode systems.
In view of this, the scientific research team of SIT proposed the strategy of in-situ reconstruction of the interface between carbon electrode and perovskite by mechanochemistry. In this study, methylamine chloride was first used to chemically activate the surface of perovskite film. The introduction of chloride and methylamine ions transformed the surface perovskite into amorphous mesphase. Nanoindentation test showed that the formation of mesphase significantly reduced the hardness of perovskite film and improved the plasticity of the film. When the carbon film is mechanically hot pressed to the activated perovskite surface, the mesophase begins to recrystallize into perovskite, which grows into a more crystalline and larger crystalline perovskite film through Oswald aging. More importantly, driven by pressure and temperature, the regrowth process of the perovskite film and the solidification of the carbon film can be carried out simultaneously, and the plasticity of the two can be used to dynamically restructure the interface between the two, effectively solving the problem of device inefficiency caused by interface contact, and increasing the efficiency of the hole-free transport layer perovskite solar cell based on the laminate carbon film to more than 20%. The above strategy of combining mechanical pressure with chemical activation provides a new idea and choice for interface regulation of perovskite solar cells.
Source: School of Chemical and Environmental Engineering
