A design of intermediate band solar cell for photon ratchet with multi-layer MoS2 nanoribbons

We presented an idea to increase the efficiency of the MoS2 solar cells with the special E-k relation of the intermediate band in MoS2 nanoribbon structures. From the calculations of armchair nanoribbon structures by the tight binding method, we found that the continuous surface states forming at the middle bandgap has the lowest energy states at X-valley. This dispersion relation will allow phonons to rapidly scatter electrons to the lower X valley of the intermediate band in pico-second scale. Simulations show that this will prevent electrons to be directly recombined with the holes in the Γ valley. After modelling the transition rates of photon absorption and emission with the solar spectrum, it shows a significant improvement of the short circuit current compared to the bulk MoS2 structures without intermediate bands.