All-perovskite tandem solar cells are expected to surpass the Shockley-Quesser limit of single-junction solar cells. However, the practical use of these cells is currently hampered by performance and stability issues associated with mixed tin-lead (Sn-Pb) narrow-bandgap perovskite subcells in all-perovskite tandems.
Fang Guoguo, Ke Weijun and others from Wuhan University focus on narrow-bandgap sub-batteries and develop an integrated doping strategy for them. We introduced aspartate hydrochloride (AspCl) into the bottom poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) and bulk perovskite layers, followed by another AspCl post-treatment.
Studies have shown that a single AspCl additive can effectively passivate defects, reduce Sn4+ impurities and change the Fermi level. In addition, the strong molecular bonds between AspCl-Sn/Pb iodide and AspCl-AspCl can strengthen the structure, thereby improving the stability of Sn-Pb perovskite. Finally, AspCl doping was implemented in Sn-Pb titanium solar cells, and the power conversion efficiency of the single-junction cell was 22.46%.
The photoelectric conversion efficiency of the tandem perovskite solar cell is 27.84% (27.62% stable efficiency, 27.34% efficiency), and the retention rate is 95% after 2,000 hours of storage in N2. These results indicate that integrated AspCl doping is a favorable strategy to improve the efficiency and stability of single-junction Sn-Pb perovskite solar cells and their tandem cells.
Zhou, S., Fu, S., Wang, C. et al. Aspartate all-in-one doping strategy enables efficient all-perovskite tandems. Nature (2023).
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