Converting waste heat into electricity through wearable thermoelectric solid-state devices is an attractive and inexpensive approach to green power generation. Although the performance of organic thermoelectric devices lags far behind that of inorganic counterparts, the abundance and non-toxicity of carbon-based materials that can be solution-processed at low temperatures simplify the fabrication process and reduce the cost of organic thermoelectrics. Now, Abol-Fotouh et al. demonstrate the growth of cellulose films from bacteria embedded with finely dispersed carbon nanotubes to produce a biodegradable thermoelectric paper.
The researchers grow the films in an aqueous solution, which simultaneously serves to stimulate the bacterial growth and disperse colloidally stable nanotubes. After a few days, flexible centimetre-size free-standing films are fully formed. As expected, the films have a low thermal conductivity (1 W m−1 K−1) and, despite a modest carbon nanotube content of just 10 weight per cent, their thermoelectric performance is comparable to that of buckypaper. The composite developed by Abol-Fotouh et al. is p-type, but it can be easily converted into n-type by doping it with, for example, polyethyleneimine. Furthermore, the cellulose can be decomposed using heat or enzymes to collect and recycle the nanotubes.
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Bubnova, O. Do-it-yourself thermoelectrics. Nat. Nanotechnol. 14, 194 (2019). https://doi.org/10.1038/s41565-019-0411-4