Research Highlights

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Hot and cold

Published online 23 June 2018

A new thin-film device can switch between different states by controlling heat flow. 

Biplab Das

Voltage-induced electrical stress can trigger chemical reactions in a semiconducting thin film, forming nanofilaments that also act as conductors, according to new research1

“Thin film with such properties is potentially useful for making power-generating devices which can convert waste heat into electricity,” says lead author José Ramón Durán Retamal from King Abdullah University of Science and Technology (KAUST), Saudi Arabia. 

The conducting filaments increase current flow inside the film and lower heat transport.  

This is also reversible; dialing down electrical stress disrupts the formation of conducting nanofilaments, reducing current flow and increasing heat transport inside the film. 

In short, by tweaking voltages that increase or decrease electrical stress, the scientists could switch between the two states.

The film thus makes it possible to achieve both cooling and power generation using the same material, says Retamal. 

The device was prepared by placing a thin film of bismuth manganese oxide between two platinum electrodes on a silicon substrate.

The researchers, led by Jr-Hau He from KAUST, say that because this electrically controllable film could produce different levels of heat and coldness, it has the potential to reduce power consumption of devices that convert waste heat into electricity. 


  1. Retamal, J. R. D. et al. A nanostructuring method to decouple electrical and thermal transport through the formation of electrically triggered conductive nanofilaments. Adv. Mater. (2018)