Conducting Foams and Fibres for Bulk Plastic Thermoelectrics

The use of small portable electronics in society is constantly increasing, thus the demand for portable power sources also rises in turn. Portable electronic devices rely upon energy stored in batteries to power them, which in turn require regular access to power outlets to be recharged. The development of organic thermoelectric materials is one potential solution towards charging devices, such as sensors and ID tags, whilst the user is mobile. This thesis discusses thermoelectrics in the context of organics, specifically the development of materials with bulk architectures, where conjugated polymers have been used to attain functioning conducting systems. We present conducting p-type silk and n-type polyester based yarns which could ultimately prove useful for drawing upon waste heat energy from the human body, for example in the form of clothing. Additionally, foams have been developed which offer low thermal conductivities, ease of doping and comparable thermoelectric performances c.f thick films considering the amount of material present. We have also demonstrated a nanocomposite system which can be switched from p-type to n-type when irradiated with UV light, which lends itself as an ink that allows for patterning during printing. Textile devices have been fabricated based upon p-type silk yarn dyed with PEDOT:PSS, which were further enhanced with n-type polyester yarn coated with a carbon nanotube composite, to produce an all-organic device which produces promising results in terms of thermoelectric output, offering an exciting direction  for the growing field of organic thermoelectrics.