Nano-engineered thin-film thermoelectric materials enable practical solid-state refrigeration

Refrigeration needs are increasing worldwide with a demand for alternates to bulky poorly scalable vapor compression systems. Here, we demonstrate the first proof of practical solid-state refrigeration, using nano-engineered controlled hierarchically engineered superlattice thin-film thermoelectric materials. With 100%-better thermoelectric materials figure of merit, ZT, than the conventional bulk materials near 300 K, we demonstrate (i) module-level ZT greater than 75% and (ii) a system-level refrigeration ZT 70% better than that of bulk devices. Thin-film thermoelectric modules offer 100-300% better coefficient-of-performance than bulk devices depending on operational scenarios; system-level coefficient-of-performance is ~15 for temperature differentials of 1.3 °C. The thin-film devices enable more heat pumping per P-N couple, relevant for distributed and portable refrigeration, and electronics cooling. Beyond the demonstration of nano-engineered materials for a system-level advantage, we utilize 1/1000^th active materials with scalable microelectronic manufacturing. The improved efficiency and ultra-low thermoelectric materials usage herald a new beginning in solid-state refrigeration.