Seminar Talk

Thermoelectrics (TE) is a green renewable energy technology which plays an import role in power generation due to its potential in generating electricity out of waste heat. The challenge for the development of thermoelectric is its low conversion efficiency. The efficiency of thermoelectric materials is related to the figure of merit, which is expressed as ZT = S2σT/, where S is the Seebeck coefficient, σ is the electrical conductivity, and is the thermal conductivity. In the quest to enhance ZT values, a key strategy involves the reduction in thermal conductivity, resulting from phonon scattering by numerous interfaces in low dimensional structures. In this study, we reported an approach to enhance thermoelectric properties of traditional lead chalcogenide films by Atomic Layer Deposition (ALD) synthesizing PbSe and PbTe/PbSe nanolaminates films on patterned porous silicon templates implemented the phonon engineering concept. This talk presents the film deposition process, the physical and thermoelectric characterization of the nanolaminates films. The effect of the patterned substrates on the Seebeck coefficient and thermal conductivity of the films was investigated and analyzed. The PbTe/PbSe nanolaminates grown on porous silicon membranes have three times higher Seebeck coefficients than the ones grown on regular planar silicon wafers. The higher Seebeck values result from the lower thermal conductivity in porous structures, which in turn lead to a higher figure of merit ZT. We demonstrated the feasibility to enhance the figure of merit ZT further by modulating the size and periodicity of the pattern and the thickness of the thermoelectric film in relation to the mean free path (MFP) of the phonons of the thermoelectric material.