The increasing energy demand and the ever more pressing need for clean technologies of energy conversion 
pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion 
of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which 
still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the 
thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with 
the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric 
figure of merit, and finally building the most efficient thermoelectric devices.
In this Roadmap an overview is given about the most recent experimental and computational results obtained
within the Italian research community on the optimization of composition and morphology of some 
thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic 
devices.

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Nanomaterials can be game-changers in the arena of sustainable energy production because they may enable highly efficient thermoelectric energy conversion and harvesting. For this purpose, doped thin film oxides have been proven to be promising systems for achieving high thermoelectric performances. In this work, the design, realization, and experimental investigation of the thermoelectric properties exhibited by a set of five Al:ZnO thin films with thicknesses of 300 nm and Al doping levels ranging from 2 to 8 at.% are described. Using a multi-technique approach, the main structural and morphological features of the grown thin films are addressed, as well as the electrical and thermoelectrical transport properties. The results show that the samples exhibited a Seebeck coefficient absolute value in the range of 22–33 μV/K, assuming their maximum doping level was 8 at.%, while the samples’ resistivity was decreased below 2 × 10−3 Ohm·cm with a doping level of 3 at.%. The findings shine light on the perspectives of the applications of the metal ZnO thin film technology for thermoelectrics.

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Fe2+-doped ZnSe nanoparticles, with varying concentrations of Fe2+ dopants, were prepared by the hydrothermal method and investigated using a multi-technique approach exploiting scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy, as well as measurement of the electrical transport properties and Seebeck coefficient (S). The doped nanoparticles appeared as variable-sized agglomerates on nanocrystallites upon SEM investigation for any doping level. Combined XRD and Raman analyses revealed the occurrence of a cubic structure in the investigated samples. Electric and thermoelectric (TE) transport investigations showed an increase in TE performance with an increase in Fe atom concentrations, which resulted in an enhancement of the power factors from 13 µWm−1K−2 to 120 µWm−1K−2 at room temperature. The results were also dependent on the operating temperature. The maximum power factor of 9 × 10−3 Wm−1K−2 was achieved at 150 °C for the highest explored doping value. The possible applications of these findings were discussed.