Generating electricity from heat

An international research team has discovered that single molecules of fullerene show bi-thermoelectric properties — in other words, positive and negative thermopower.  

These molecules display such properties when exposed to different pressures and voltages applied using a scanning tunneling microscope (STM)¹.  

“These single molecules of fullerene could potentially be used to make thin-film devices that would convert heat into electricity,” says Colin Lambert of Lancaster University, UK. 

Since inorganic materials that can convert heat into electricity are generally toxic and expensive, the research team, including researchers from Tikrit University in Iraq, explored the thermoelectric properties of single molecules of fullerene by placing them between two gold electrodes. These molecules contained three scandium atoms joined to one nitrogen atom inside their cage-like structure. 

The scientists applied pressures and voltages by advancing the tip of the STM close to single molecules at ambient conditions. They found that some molecules had higher conductance for positive voltage, while others had higher conductance for negative voltage. 

As the tip pressed the molecules, their conductance increased with thermopower showing positive and negative signs. Such thermopower can be harnessed to generate voltage in thermoelectric devices, the researchers say.   

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