The unexpected imprints of the tug of war between quantum coherence and environmental noises on the efficiency at the maximum power of a molecular photocell.*

The molecular photocell, i.e., a single-molecule donor-acceptor complex placed between two external leads, besides being technologically important, is a paradigmatic example of a many-body system operating in strong nonequilibrium. There exist parameter regimes where an intricate interplay between environmental noise and quantum coherence effectively increases the efficiency of the transport process, a phenomenon, known as, “environment assisted quantum transport,” or ENAQT in short. We discuss, within the set-up of a molecular photocell, that while a single environment can assist quantum transport, the combined effect of more than one type of environment can, quite counterintuitively, hamper the transport efficiency over a broad parameter regime. The efficiency at maximum power provides clear signatures of such surprising behaviors. Our findings are verifiable given recent advances in the experimental ability.