9.13%-Efficiency and stable inorganic CsPbBr3 solar cells. Lead-free CsSnBr3-xIx quantum dots promote charge extraction.

Abstract Interfacial charge recombination seriously drags efficiency enhancement of all-inorganic perovskite solar cells (PSCs) because of large energy-level differences. Although CsPbBr 3-x I x light-harvesters markedly reduce interfacial charge recombination, the long-term stability of solar cell devices is still unsatisfactory to meet practical requirements. Here we present the improved charge extraction by setting an intermediated energy-level at CsPbBr 3 /carbon interface with colorful CsSnBr 3-x I x quantum dots (QDs). The charge extraction is maximized by tuning Br:I ratio, yielding a power conversion efficiency as high as 9.13% for CsSnBr 2 I QDs-tailored CsPbBr 3 solar cell. Moreover, all the devices show high stability in 80%RH or 80 °C over 720 h. The interfacial decoration of all-inorganic perovskite solar cells by lead-free perovskite QDs provides new opportunities of enhancing solar cell efficiency and reducing environmental impacts. Highlights • PQDs with tunable bandgaps are synthesized to modify CsPbBr 3 /carbon interface. • An intermediate energy level is set at CsPbBr 3 /carbon interface to extract holes. • The electron-hole recommendation is markedly restricted. • A maximized PCE of 9.13% is achieved for the PQDs tailored inorganic PSC. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]