We develop the hybrid thermodynamic limit model using the intermediate band solar cells assisted with multiple exciton generation under blackbody radiation. For this hybrid solar cell model, we manage the spectral splitting to maximize the generated number of electron and hole pairs (EHP). First, we have separated two areas to explain the carrier transition. For regarding of quantum yield and charge neutrality, the multiple EHPs are generated at barrier bandgap and one carrier generation is in quantum dot. Thus, to extract additional carrier in quantum dot, it is required additional absorption paths or more photon energy. After studying the procedure of carrier multiplication in intermediate band solar cells, we have calculated the theoretical conversion efficiencies with number of generated EHPs. Its maximum theoretical efficiencies are increased and optimum bandgap is lowered compared to conventional intermediate band solar cells. And, based on these results, we can also choose the suitable material for these hybrid solar cells.