Inorganic cesium lead bromide (CsPbBr3) perovskite solar cells (PSCs) have superior moisture- and thermal-stability in comparison with organic-specie or/and I-containing devices. However, the narrow-spectra absorption (<550 nm) arising from their large bandgap of 2.3 eV for CsPbBr3 halide has markedly limited the further efficiency enhancement of corresponding inorganic device, therefore a great challenge is to broaden the light response range without sacrificing environmental tolerances. In this work, we constructively fabricate a CsPbBr3/bulk-heterojunction (organic J61-ITIC) photoactive layer to widen the optical absorption range of inorganic CsPbBr3 based interlayer-free device. Arising from the broadened light response wavelength from 550 to 780 nm and precisely optimized crystal lattice by incorporating Rb+ into CsPbBr3 film, the optimal device achieves a power conversion efficiency up to 10.34% under one sun illumination. Upon persistent attacks by heat of 80 °C (0% humidity) or 90% humidity (25 °C) over 40 days, the solar cell can still remain approximately 96% of initial efficiency, demonstrating the excellent stability for practical application.