Conducting-Polymer Bolometers for Low-Cost IR-Detection Systems

Semiconducting polymers are promising materials for manufacturing optoelectronic devices, such as large-area solar cells or small light-emitting diodes, through the use of printing technologies. In their oxidized form, π-conjugated polymers become good electrical conductors and their optical absorption shifts to the infrared region. It is demonstrated that conducting polymers can be integrated in bolometers for IR detection. A bolometer is a thermally isolated thin device that absorbs IR radiation and translates a temperature change into a change in electrical resistance. While commercial bolometers are usually made of complex architectures comprising several materials (that is, an IR absorbing layer, a conducting layer, and a thermally insulating layer), the first polymer bolometer is demonstrated with a freestanding layer of poly(3,4-ethylene-dioxythiophene) having high IR absorption, low thermal conductivity, and good thermistor action in one single layer. The solution processability of conducting polymers, their compatibility with high-resolution printing technologies, and their unique combination of optoelectronic properties can lead to a breakthrough for low-cost uncooled IR cameras, which are in high demand for security and safety applications.