Wide-bandgap all-inorganic CsPbIBr 2 solar cells with MoO x /Ag/TeO 2 composite transparent electrode have been firstly used to construct a 4T perovskite/Si-heterojunction tandem cells. The calculation results showed that the long wavelength transmission (600 to 1100 nm) of MoO x /Ag film can be enhanced remarkably by adding a TeO 2 optical capping layer. This resulted in an obviously increase of the PCE (J SC ) from 10.70% (17.56 mA/cm 2 ) to 14.76% (24.67 mA/cm 2 ) for corresponding bottom Si cell in CsPbIBr 2 /Si devices, although the PCE of top CsPbIBr 2 cell decreased from 17.52% to 16.58%, the overall PCE of tandem device has increased from 28.22% to 31.34%. This J SC -dependent PCE improvement mainly came from the more balanced light absorption, which can be understood by the optical interference induced light field redistributions in CsPbIBr 2 /Si devices. Specially, comparing with the original Si cell, the J SC and PCE losses in bottom Si cell have been suppressed to about 33% and 32%, which are superior to most the reported pervoskite/Si tandem cells. Therefore, the tandem of Si cell and CsPbIBr 2 cell with optimized MoO x (20 nm)/Ag(8 nm)/TeO 2 (50 nm) transparent electrode could be the promising cost-effective photovoltaic in the future. This work is instructive to the fabrication of pervoskite/Si tandem solar cells.