Photovoltaic power generation is a new force in the global green transformation. The scientific research team of Beijing Institute of Technology and other domestic units cooperated and successfully broke through the technical difficulties in the preparation of perovskite/crystalline silicon tandem solar cells, and developed a perovskite/crystalline silicon tandem solar cell with a photoelectric conversion efficiency of 32.5% and long-term operation stability. The relevant results were published in the international academic journal "Science" on the 2nd.
At present, the more common solar cells in production and life are crystalline silicon cells, whose photoelectric conversion efficiency is about 26%. The perovskite/crystalline silicon stacked cell is a new type of solar cell that is composed of a combination of crystalline silicon and perovskite to absorb light. Compared with traditional crystalline silicon cells, it has the characteristics of low power generation cost and high photoelectric conversion efficiency. For a long time, problems such as uneven perovskite films and poor crystal quality have often occurred during the preparation process of this new type of battery, resulting in defects in the finished product and affecting the photoelectric conversion rate and service life.
The picture shows the perovskite/crystalline silicon stacked solar cell prototype device developed by the Beijing Institute of Technology research team and others. (Photo provided by interviewee)
"To prepare this kind of tandem battery, a layer of perovskite precursor liquid is first deposited on the crystalline silicon cell. When the precursor liquid dries, it gradually forms crystal nuclei and crystallizes, and finally 'grows' into a wide-bandgap perovskite film. However, due to the diverse components in the perovskite material and the complex phase state of the seed crystals, the 'grown' film is uneven. Chen Qi, a professor at the Institute of Frontier Interdisciplinary Science at BIT, said that the team innovatively proposed a wide-bandgap perovskite crystallization control strategy, adding long-chain alkyl amines to the precursor solution to accelerate the "growth" of high-quality crystal nuclei and inhibit the "growth" of low-quality crystal nuclei, thereby preparing a uniform, high-quality wide-bandgap perovskite film.
Chen Yihua, assistant professor at the School of Materials Science and Engineering at BIT, said that based on this innovative idea, the team prepared 1 square centimeter and 25 square centimeter perovskite/crystalline silicon stacked cells respectively, with corresponding photoelectric conversion efficiencies of 32.5% and 29.4%, both better than traditional crystalline silicon solar cells. In addition, after maximum power point tracking testing, the sample demonstrated long-term operational stability.
Chen Qi said that this achievement lays a key technical foundation for the development of perovskite/crystalline silicon stacked solar cells, and is expected to promote their industrial application, improve photovoltaic power generation efficiency, and assist in the green and low-carbon transformation of energy. (Reporter Zhao Xu)