Hefei Research Institute Uses Excimer Laser Technology To Improve The Performance Of Perovskite Solar Cells

Fang Xiaodong, researcher at the Laser Technology Center of Anhui Institute of Optics and Fine Mechanics, Institute of Material Science, Chinese Academy of Sciences , made new progress in using excimer laser technology to improve the performance of perovskite solar cells (PSCs ).

Since its first report in 2009 , PSCs have developed rapidly. At present, its photoelectric conversion efficiency has surpassed that of polycrystalline silicon solar cells, reaching 24.2% , which is very promising. The light-absorbing layer organic-inorganic hybrid perovskite film of PSCs is usually prepared by solution method at low temperature (< 150 °C ), which can not only construct rigid solar cells but also have the natural advantage of developing flexible solar cells. However, there are a large number of defects on the surface of the perovskite film prepared by the solution method, resulting in recombination of photogenerated carriers, which hinders further improvement of battery performance. At the same time, the preparation process of common electron transport layers of PSCs needs to be annealed at a temperature of 400~500 °C , and this temperature exceeds the temperature that can be withstood by common flexible substrates, which restricts the development of flexible PSCs .

In view of the above problems, combined with excimer laser photon energy, large single pulse energy, short pulse time, large spot area, uniform energy distribution and small thermal effect, the research team introduced excimer laser technology into PSCs research. Excimer laser irradiation effectively reduces the surface defect concentration of the perovskite film and realizes low temperature excimer laser annealing of the electron transport layer.

The researcher Wang Shimao and the doctoral student Shan Xueyan used surface modification of the CH₃NH ₃PbI₃ film by 248 nm ( KrF ) excimer laser. The defect concentration of themodified CH₃NH ₃PbI₃ film decreased from 1.61×10 ¹⁶ cm ^-3 to 5.81×10¹⁵ cm^-3 . The transient fluorescence lifetime test showed that the non-radiative recombination of photogenerated carriers in the film under illumination was obtained. With effective suppression, the photoelectric conversion efficiency of the battery has also been significantly improved. The related research results were published in the Advanced Materials magazine Solar RRL with thetopic of rapid surface modification of CH₃NH ₃PbI₃ film with 248 nm KrF excimer laser toenhance the performance of perovskite solar cells .

The research team's associate researcher Dong Weiwei and doctoral student Xia Rui first applied excimer laser annealing ( ELA ) technology to the preparation of PSCs electron transport layer, using 308 nm ( XeCl ) excimer laser for magnetron sputtering. The prepared gallium-doped zinc oxide ( GZO ) electron transport layer is annealed. After ELA treatment, the crystallinity, transmittance and electrical conductivity of the GZO film, and the photoelectric conversion efficiency and stability of the PSCs based thereon were significantly improved. Related results in "perovskite solar Ga -doped ZnO electron transport layer, excimer laser annealing" was published in the RSC Advances on.

Both of the above studies are compatible with existing low temperature polysilicon annealing technology and are expected to be used in the production of commercial rigid and flexible PSCs in the future.

The above research was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences Hundred Talents Program, the Chinese Academy of Sciences - Japan Society for the Promotion of Science ( CAS-JSPS ) joint project and the Chinese Academy of Sciences Key Laboratory of Photovoltaic and Energy-Efficient Materials.