Enhanced charge extraction by setting intermediate energy levels in all-inorganic CsPbBr3 perovskite solar cells

Perovskite-structured CsPbBr3 halide is an emerging light-harvester for all-inorganic solar cells due to its superior stability against moisture and heat. However, the wide bandgap of CsPbBr3 (2.3 eV) calls for serious charge recombination and low efficiency in its photovoltaics. We present here all-inorganic CsPbBr3 perovskite solar cells (PSCs) by modifying TiO2/CsPbBr3 and CsPbBr3/carbon interfaces with carbon quantum dots (CQDs) and phosphorus quantum dots (PQDs), respectively. The electron and hole extractions are markedly enhanced by setting intermediate energy levels, and the optimized PSC achieves a power conversion efficiency of 7.93% in comparison with 6.05% for the device free of CQDs and PQDs. Moreover, the unsealed PSCs are highlighted by long-term stability in high humidity over 1400 h. This work may provide new opportunities of promoting charge extraction at CsPbBr3/charge-transporting material interfaces.