In this paper, we propose an innovative concept for solar power conversion—the “photon ratchet” intermediate band solar cell (IBSC)—which may increase the photovoltaicenergy conversion efficiency of IBSCs by increasing the lifetime of charge carriers in the intermediate state. The limiting efficiency calculation for this concept shows that the efficiency can be increased by introducing a fast thermal transition of carriers into a non-emissive state. At 1 sun, the introduction of a “ratchet band” results in an increase of efficiency from 46.8% to 48.5%, due to suppression of entropy generation.