Liquid thermoelectric conversion devices composed of several organic solvents

We evaluated the performances of liquid thermoelectric conversion devices (LTEs) composed of nine organic solvents containing an Fe2+/Fe3+ redox pair against the electrolyte concentration (m). In protic solvents, i.e. methanol (Me), ethanol (Et), 1-propanol (Pr), and ethylene glycol (EG), the electrochemical Seebeck coefficient (α = d V/d T, where V and T are the electrode potential and temperature, respectively) increases with m in the small m region. Based on the ultraviolet—visible absorption spectroscopy, we interpreted the enhancement of α in terms of the OH− and/or H2O coordination to Fe3+, which was introduced by the crystal water of the solute. At a temperature difference (ΔT) of 30 K, the maximum value of the power factor of the Me LTE reaches 11.5 μW K−2m.