After long-term research, Professor Ke Weijun and Professor Fang Guoguo from the School of Physical Science and Technology of Wuhan University have made new progress in exploring the performance improvement of fully perovskite stacked solar cells. They have creatively proposed an integrated doping strategy of aspartate hydrochloride, effectively improving the efficiency and stability of narrow bandgap perovskite solar cells, and finding new ways to further improve battery performance. The relevant research results were recently published in the journal Nature. It is reported that the novel metal halide perovskite has the advantages of simple preparation process, high defect tolerance, high absorption coefficient, and long carrier diffusion length. It has attracted great attention in the field of optoelectronic devices and is considered one of the promising next-generation photovoltaic materials in the industry. One of the corresponding authors of the paper, Professor Ke Weijun from the School of Physical Science and Technology of Wuhan University, stated that in practical applications, all perovskite stacked solar cells are composed of a broadband gap perovskite sub cell at the top and a narrow band gap perovskite sub cell at the bottom, which are not outstanding enough. The narrow band gap perovskite sub cell is one of the obstacles to its future commercial application. To this end, the research team introduced aspartic acid hydrochloride into the hole transport layer, perovskite absorbing layer, and upper interface layer at the bottom of the fully perovskite stacked solar cell, and developed an integrated doping strategy using the same molecule treatment, greatly improving the quality of perovskite thin films. In addition to coordinating with perovskite precursors, aspartic acid hydrochloride molecules also have strong intermolecular hydrogen bonds. The aspartic acid hydrochloride enriched at the upper and lower interfaces of perovskite acts as a molecular lock between the perovskite layer and the transport layer interface, further improving the performance and stability of perovskite materials. In addition, how to suppress the unstable spontaneous oxidation of divalent tin metal ions in narrow bandgap perovskite solar cells is also one of the industry pain points. The results of this study indicate that aspartic acid hydrochloride can effectively inhibit the oxidation of divalent tin metal ions and reduce harmful tetravalent tin impurities. Moreover, the introduction of aspartic acid hydrochloride can also passivate defects in perovskite materials, regulate Fermi energy levels, suppress harmful ion migration, and enhance the performance and stability of devices. Schematic diagram of battery preparation process, structure and efficiency diagram of stacked batteries. (Courtesy of Professor Ke Weijun and Professor Fang Guoguo from the School of Physical Science and Technology, Wuhan University) Ke Weijun said that research has shown that this simple integrated doping strategy achieves multiple functions in one go, increasing the steady-state efficiency of narrow bandgap perovskite solar cells to 27.62%, providing a new way to improve the performance of all perovskite stacked solar cells. (Reporter Hou Wenkun) (Xinhua News Agency)