Xinhua News Agency, Wuhan, November 12 (Reporter Hou Wenkun) After long-term research, Professor Ke Weijun and Professor Fang Guo from the School of Physical Science and Technology of Wuhan University have made new progress in exploring the performance improvement of all-perovskite laminated solar cells, and creatively put forward the integrated doping strategy of aspartic acid hydrochloride, which effectively improved the efficiency and stability of narrow-band gap perovskite subcells and found new ways to further improve the battery performance. Related research results were recently published in the journal Nature.
According to reports, the new metal halide perovskite has the advantages of simple preparation process, high defect tolerance, high absorption coefficient and long carrier diffusion length, which has attracted much attention in the field of optoelectronic devices and is considered as one of the next generation photovoltaic materials with great prospects in the industry.
Ke Weijun, one of the authors of the paper and a professor at the School of Physical Science and Technology of Wuhan University, said that in practical application, the all-perovskite laminated solar cell is composed of a broad-band gap perovskite subcell at the top and a narrow-band gap perovskite subcell at the bottom, and the narrow-band gap perovskite subcell that is not excellent enough is one of the stumbling blocks for its commercial application in the future.
To this end, the research team introduced aspartic acid hydrochloride into the hole transport layer, perovskite light absorption layer and upper interface layer at the bottom of all perovskite laminated solar cells, and developed an integrated doping strategy with the same molecular treatment, which greatly improved the quality of perovskite thin films. In addition to coordinating with perovskite precursors, aspartic acid hydrochloride molecules also have strong intermolecular hydrogen bonds, so aspartic acid hydrochloride enriched at the upper and lower interfaces of perovskite acts as a molecular lock between the interface of perovskite layer and transport layer, further improving the performance and stability of perovskite materials.
In addition, how to inhibit the spontaneous oxidation of unstable divalent tin metal ions in narrow-gap perovskite subcells is also one of the pain points in the industry. The results show that aspartic acid hydrochloride can effectively inhibit the oxidation of divalent tin ions and reduce harmful tetravalent tin impurities. Moreover, the introduction of aspartic acid hydrochloride can also passivate the defects of perovskite materials, adjust Fermi level and inhibit harmful ion migration, thus enhancing the performance and stability of devices.
Ke Weijun said that the research shows that this simple integrated doping strategy can achieve multiple functions at one stroke and improve the steady-state efficiency of narrow-band perovskite subcells to 27.62%, which provides a new way to improve the performance of all-perovskite stacked solar cells.
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