Doping of perovskite semiconductors1 and passivation of their grain boundaries2 remain challenging but essential for advancing high-efficiency perovskite solar cells. Particularly, it is crucial to build perovskite/indium tin oxide (ITO) Schottky contact based inverted devices without predepositing a layer of hole-transport material3,4,5. Here we report a dimethylacridine-based molecular doping process used to construct a well-matched p-perovskite/ITO contact, along with all-round passivation of grain boundaries, achieving a certified power conversion efficiency (PCE) of 25.39%. The molecules are shown to be extruded from the precursor solution to the grain boundaries and the bottom of the film surface in the chlorobenzene-quenched crystallization process, which we call a molecule-extrusion process. The core coordination complex between the deprotonated phosphonic acid group of the molecule and lead polyiodide of perovskite is responsible for both mechanical absorption and electronic charge transfer, and leads to p-type doping of the perovskite film. We created an efficient device with a PCE of 25.86% (reverse scan) and that maintained 96.6% of initial PCE after 1,000 h of light soaking.
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We thank W. Tian and S. Jin from the Dalian Institute of Chemical Physics (Chinese Academy of Sciences) for transient absorption testing and data analysis, H. He from the Department of Physics (SUSTech) for discussions on semiconductor physics and W. Lu and L. Chung from the Department of Chemistry (SUSTech) for discussions on coordination chemistry. The authors thank Core Research Facilities, Department of Materials Science and Engineering for characterizations, and the Center of Computational Science and Engineering of SUSTech for calculations. We also thank the National Natural Science Foundation of China (nos. U2001216 and 52273266), the Shenzhen Key Laboratory Project (no. ZDSYS201602261933302), the Guangdong Provincial Key Laboratory of Computational Science and Material Design (grant no. 2019B030301001) and the Shenzhen Science and Technology Innovation Committee (no. JCYJ20200109141412308).
A Chinese patent application (no. 2023100349666), submitted by SUSTech, covers the AcPA series molecule-based molecule-extrusion process for the fabrication of HTL-free perovskite solar cells.
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Tan, Q., Li, Z., Luo, G. et al. Inverted perovskite solar cells using dimethylacridine-based dopants. Nature 620, 545–551 (2023). https://doi.org/10.1038/s41586-023-06207-0