Electrical and Morphological Characterization of Annealed Solution-deposited Cu2Se Nanoparticle Thin-films

Authors

Noah B. Lupu-Gladstein, Macalester CollegeFollow

Document Type

Honors Project On-Campus Access Only

Abstract

Thermoelectric devices are an emerging green technology that turn heat into electricity or vice versa without any moving parts. They have not yet seen wide-spread use outside of niche applications because thermoelectric materials are either too costly or too inefficient. Copper Selenide (Cu₂Se) has one of the highest thermoelectric efficiencies of any bulk material and it can be synthesized inexpensively via solution-deposition. We characterize thin-films of solution-deposited Cu₂Se nanoparticles annealed at different temperatures. The direct current (DC) and terahertz (THz) conductivities of samples annealed at 200 °C or above are two orders of magnitude greater than that of the 100 °C and unannealed sample. We find the THz conductivity of samples annealed at 300 °C or greater to be frequency-independent, thus their electrical properties are closer to that of a polycrystalline thin metal film than a nanomaterial. We measure DC and THz conductivity as a function of temperature and observe a feature at 350 K attributable to Cu₂Se's second-order phase transition to super-ionic conductivity. This is 60 K cooler than the transition temperature in bulk Cu₂Se. Both DC and THz conductivity exhibit hysteresis over temperature cycling when heated past the phase transition.

Recommended Citation

Lupu-Gladstein, Noah B., "Electrical and Morphological Characterization of Annealed Solution-deposited Cu2Se Nanoparticle Thin-films" (2016). Physics and Astronomy Honors Projects. 21.
https://digitalcommons.macalester.edu/physics_honors/21