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Hybrid organo-metal halide perovskite solar cells (PSCs) are promising candidates for next generation photovoltaic device primarily due to their high efficiency, printability and low cost. PSCs have exhibited externally verified power conversion efficiencies (PCE) up to 25.7% in single junction, which have encouraged recent efforts on scalable coating technique in PSCs towards manufacturing. Effective interface passivations of the buried and top perovskite film are among the most important issues to address for reducing energy loss, high efficiency and stability. 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 SnO¬2 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. [1] Combined with 2D/3D graded interfacial passivation, 23.7% PCE was achieved, with significantly enhanced stability. [2]
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