Precise stress control of inorganic perovskite films for carbon-based solar cells with an ultrahigh voltage of 1.622 V

All-inorganic cesium lead bromide (CsPbBr 3 ) perovskite solar cell is one promising candidate to balance high efficiency and poor stability of organic-inorganic hybrid photovoltaics . The charge carrier transport can be maximized for high-efficiency devices through precise stress control during perovskite grain growth process to obtain high-quality full-bromine CsPbBr 3 halide films. We present here the monolayer-aligned and large-grained CsPbBr 3 perovskite films through precise control of crystallization temperature of PbBr 2 film because the lattice volume is enlarged by 2.18 times during the phase conversion from PbBr 2 to CsPbBr 3 , which helps to minimize residual-stress-induced grain boundaries and defect-induced charge recombination. Upon further interfacial modification by nitrogen doped carbon quantum dots , the hole transporting materials free, all-inorganic CsPbBr 3 perovskite solar cell achieves a champion efficiency as high as 10.71% with an ultrahigh open-circuit voltage of 1.622 V. Moreover, the unencapsulated solar cell demonstrates remarkable long-term stability in 85% humidity in air atmosphere.