thermopile

https://doi.org/10.1351/goldbook.T06335
Several thermocouples connected in series to increase the magnitude of the electric potential.
Source:
PAC, 1995, 67, 1745. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-XI. Detection of radiation (IUPAC Recommendations 1995)' on page 1752 (https://doi.org/10.1351/pac199567101745)