Reduced interface energy loss in non-fullerene organic solar cells using room temperature-synthesized SnO2 quantum dots

We herein report the room temperature synthesis of colloidal SnO2 quantum dots and their application in non-fullerene organic solar cells as an excellent electron transport layer. The thiourea-assisted hydrolysis at room temperature affords the nanocrystalline SnO2 quantum dots with a diameter of 3−4 nm. The utilization of the SnO2 quantum dots as an electron transporting layer effectively reduces the interfacial trap density and charge recombination in the solar cell devices, leading to not only the reduced energy loss but also excellent photocurrent generation. The optimized organic solar cells employing SnO2 quantum dots with polyethylenimine ethoxylated achieves power conversion efficiencies up to 12.023 % with a VOC, a JSC, and a FF of 0.89 V, 18.89 mA cm–2, and 0.72. This work suggest that the SnO2 quantum dot is a promising electron transporting material to construct efficient organic solar cells for practical applications. This work also demonstrates the key strategy for thiourea-assisted hydrolysis to synthesize fine and nanocrystalline SnO2 quantum dots.