PbSeTe-based quantum dot superlattice structures grown by molecular beam epitaxy have been investigated for applications in thermoelectrics. We demonstrate improved cooling values relative to the conventional bulk (Bi,Sb)2(Se,Te)3 thermoelectric materials using a n-type film in a one-leg thermoelectric device test setup, which cooled the cold junction 43.7 K below the room temperature hot junction temperature of 299.7 K. The typical device consists of a substrate-free, bulk-like (typically 0.1 millimeter in thickness, 10 millimeters in width, and 5 millimeters in length) slab of nanostructured PbSeTe/PbTe as the n-type leg and a metal wire as the p-type leg.

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Currently, the materials with the highest thermoelectric figure of merit (ZT) are one-band materials. The presence of both electrons and holes lowers ZT, so two-band materials such as semimetals are not useful thermoelectric materials. However, by preparing these materials in the form of two-dimensional quantum-well superlattices, it is possible to separate the two bands and transform the material to an effective one-carrier system. We have investigated theoretically the effect of such an approach and our results indicate that a significant increase in ZT may be achieved. This result allows the possibility of using a new class of materials as thermoelectric refrigeration elements.