The benchmark tin oxide (SnO2) electron transporting layers (ETLs) have enabled remarkable progress in planar perovskite solar cell (PSCs). However, the energy loss is still a challenge due to the lack of "hidden interface" control. We report a novel ligand-tailored ultrafine SnO2 quantum dots (QDs) via a facile rapid room temperature synthesis. Importantly, the ligand-tailored SnO2 QDs ETL with multi-functional terminal groups in situ refines the buried interfaces with both the perovskite and transparent electrode via enhanced interface binding and perovskite passivation. These novel ETLs induce synergistic effects of physical and chemical interfacial modulation and preferred perovskite crystallization-directing, delivering reduced interface defects, suppressed non-radiative recombination and elongated charge carrier lifetime. Power conversion efficiency (PCE) of 23.02% (0.04 cm2) and 21.6% (0.98 cm2, VOC loss: 0.336 V) have been achieved for the blade-coated PSCs (1.54 eV Eg) with our new ETLs, representing a record for SnO2 based blade-coated PSCs. Moreover, a substantially enhanced PCE (VOC) from 20.4% (1.15 V) to 22.8% (1.24 V, 90 mV higher VOC, 0.04 cm2 device) in the blade-coated 1.61 eV PSCs system, via replacing the benchmark commercial colloidal SnO2 with our new ETLs.
KAUST Repository Item: Exported on 2022-01-27
Acknowledgements: This work was financially supported by the Research Grants Council of Hong Kong (GRF grant nos. 15246816, 15218517 and CRF grant no. C5037-18G), Shenzhen Technology Innovation Commission (Project no. JCYJ20200109105003940), and the funding provided by the Hong Kong Polytechnic University (Project Code: 1-CDA5 and Sir Sze-yuen Chung Endowed Professorship Fund (8-8480)). S/TEM work was carried out at the Hong Kong Polytechnic University and was supported by the Hong Kong Research Grants Council through the Early Career Scheme (Project no. 25301617) and the Hong Kong Polytechnic University grant (Project no. 1-ZE6G). X.G. and Y.Z. thank Dr. Wei Lu for optimizing the JEOL JEM-2100F microscope. G.L. and K.L. thank the RGC Postdoctoral Fellowship Scheme (PDFS2021-5S04). K.L. thanks Guangdong Basic and Applied Basic Research Foundation (2020A1515110156). H.H. gratefully acknowledge the support from the National Natural Science Foundation of China (62004129). A.N. and C.S. acknowledge the financial support from Nazarbayev University Grant (090118FD5326 and 110119FD4506), the targeted Program BR05236524, and social policy grants.