Energy Cooperation In Quantum Thermoelectric Systems With Multiple Electric Currents

Thermoelectric phenomena at nanoscales have attracted broad research interest for their relevance with fundamental physics,material science and renewable energy.Understanding and harnessing thermoelectric transport at the nanoscales may lead to various applications,including heat and energy detectors,heat rectifiers,refrigerators and energy transduction.The energy efficiency and output power of a quantum thermoelectric system with multiple electric currents and only one heat current are studied.The system is connected to the hot heat bath(cold bath)through one terminal(multiple terminals).In such configurations,there are multiple thermoelectric effects coexisting in the same system.Using the Landauer-Buttiker formalism,we show that the cooperation between the two thermoelectric effects in three-terminal thermoelectric systems can lead to markedly improved performance of the heat engine.Such improvement also occurs in four-terminal thermoelectric heat engines with three output electric currents.Cooperative effects in these multi-terminal thermoelectric systems can considerably enlarge the physical parameter region that realizes high energy efficiency and output power.For refrigeration,we find that the energy efficiency can also be substantially improved by exploiting cooperative effects in multi-terminal thermoelectric systems.All these results reveal a useful approach toward high-performance thermoelectric energy conversion in multi-terminal mesoscopic systems.