The detailed balance of multiple exciton generation and tandem hybrid photovoltaic devices are calculated for standard AM1.5G spectrum with one sun. We also obtain the efficiencies both unconstrained and constrained connection. The quantum yield is set to 2 to maximize the multiple exciton generation. The maximum efficiencies of two stacks unconstrained and constrained connection are 48.77% and 47.88% in AM1.5G. Its optimum bandgaps for unconstrained connection are Eg1: 0.7 eV and Eg2: 1.82eV as well as optimum bandgaps for constrained connection are Eg1: 0.57eV and E g2: 1.38eV. For three stacks of unconstrained and constrained connection, the maximum efficiency is 52.78% and 51.78% respectively. The optimum bandgaps of unconstrained connection are Eg1: 0.69eV, E g2: 1.64 eV and Eg3 2.25eV. The optimum bandgaps of constrained connection are Eg1: 0.7eV, Eg2: 1.2 eV and Eg3 1.8 eV.