(Invited) Mechanism of a Sensitized Thermal Cell

Efficient and low-cost thermal energy-harvesting systems are crucial to solve the global energy problem. A new energy conversion system for the generation of electric power directly from heat energy is described herein. The device is a sensitized thermal cell (STC) based on a dye-sensitized solar cell. In the established system, thermally-excited electrons in a semiconductor were utilized instead of photon-excited electrons in a dye. Consequently, the STC generated electricity by “placing” or “burying” the cell in the heat source. To prove the concept, first, we examined the redox ability of thermally excited electrons (Mater. Horiz., 2017, 4, 649–656.). Next, we demonstrated that the semiconductor-sensitized solar cell can generate electric power by thermally excitation (ACS Applied Energy Materials, 2019, 2, 13–18.; J. Phys. Chem. C, 123, 2019, 12135-12141.). Lastly, we performed the long-time power generation at 80 degree using STC and observed the end; and surprisingly found that the battery characteristics were restored after discharging by placing or burying the battery in a heat source ( J. Mater. Chem. A, 2019, 7, 18249-18256.). Additinally, we show that the open circuit voltage of STC has the Fermi level dependnce of the semiconductor electrode (Chem. Lett. in press). In the presentation, these recent results were summarized and the difference between photo excitation and thermally excitation will be discussed..