A hybrid model integrating photon-enhanced thermionic emission (PETE) solar cells and electron tunnels is proposed. Photon-excited electrons that occupy energy levels beyond windowed limits are first imprisoned inside the cathode, then given opportunities to rapidly re-thermalize, and eventually allowed to enter the tunnel. Energies wasted by both the irreversibility and the recombination are minimized with respect to the transmission energy and the transmission window that characterize the tunnel. The proposed model yields efficiencies that are higher than those of most existing photovoltaic cells, and may pave the foundation for the future development of photon-to-electron converters. (C) 2016 Elsevier Ltd. All rights reserved.