China's scientific research team has set a new world record for the photoelectric conversion efficiency of large-area all-perovskite photovoltaic modules. The reporter learned from Nanjing University that the large-area all-perovskite photovoltaic module developed by Professor Tan Hairen's research group has made a new breakthrough, and its steady-state photoelectric conversion efficiency has reached 245%, setting a new world record for such components, and also laying a technical foundation for subsequent industrialization development. Related**Published in the international academic journal Science on February 23.
According to Tan Hairen, perovskites are one of the key research and development directions of new solar cells. Compared with traditional crystalline silicon materials, perovskite photovoltaic modules are lighter and thinner, and have good characteristics such as bendability and translucency, and have more application scenarios. In recent years, Hairen Tan's research group has been committed to the study of perovskites, and has achieved a photoelectric conversion efficiency of 28% for small-area cells and 21% for large-area tandem modules7% and other results.
Tandem modules are stacked by sub-cells with different bandgaps, and narrow-bandgap sub-cells can absorb light that wide-bandgap sub-cells cannot absorb, and theoretically, the photoelectric conversion efficiency of tandem modules should be higher,21The 7 per cent result is clearly not satisfactory. * Gao Han, co-first author and 2019 Ph.D. student of Nanjing University, told reporters that the small-area battery prepared in the laboratory is only about 1 square centimeter, and the real commercial value is the module, so it is necessary to break through the efficiency barrier of large-area stacked modules.
The difficulty lies in the production process of narrow bandgap perovskite films. "The crystallization process of narrow bandgap perovskite films is too fast and difficult to control, and the problem of uneven film will occur when preparing in a large area. Moreover, the crystallization process of perovskite is not synchronized up and down, which can easily lead to a large number of defects at the bottom of the film. Gao Han said.
This is the all-perovskite photovoltaic module developed by Tan Hairen's research group of Nanjing University. (Photo courtesy of the interviewee).
In order to solve this problem, Hairen Tan's group added glycamide hydrochloride to the precursor solution, which can slow down the crystallization rate of perovskite, extend the preparation time of the film to about 10 times, and spontaneously induce the repair of bottom defects.
Gao Han said that the narrow-bandgap perovskite film fabricated by this method is combined with the wide-bandgap perovskite film to form a tandem module area of 2025 square centimeters. After testing by an international authoritative third-party organization, the component has obtained 24The photoelectric conversion efficiency of 5% is included in the international "Solar Cell Efficiency Table", and no similar module has broken this record at present.
Tan Hairen said that this breakthrough has laid a technical foundation for subsequent development, "We will continue to try to prepare all-perovskite photovoltaic modules with larger area and higher efficiency, and move forward steadily towards the goal of industrialization." ”