Textile-Integrated ZnO-Based Thermoelectric Device Using Atomic Layer Deposition

| openaire: EC/FP7/339478/EU//LAYERENG-HYBMATHerein, a full thermoelectric (TE) device fabricated on textile using atomic layer deposition (ALD) and molecular layer deposition (MLD) thin-film techniques is demonstrated. The device consists of n-type ALD-grown ZnO or ALD/MLD-grown ZnO-organic components and p-type spray/immersion-coated PEDOT:PSS components. Different fabrication strategies and device designs (vertical and longitudinal) are investigated. The performance is evaluated by measuring the open-circuit voltage generated by the device over a range of temperature differences (between the hot and cold sides) up to 60 °C. At a fixed ΔT, the voltage generated is found to increase with increasing ZnO or ZnO-organic film thickness. An attractive feature with both ALD and MLD is that the film grows in a conformal manner on the textile fibers so that the entire textile piece becomes an active part of the device, corresponding to a remarkable coating-thickness increase. The voltage generated can also be increased by combining more TE pairs (even by just increasing the number of pairs by cutting the TE pads into smaller pieces). This research has thus proven the feasibility of ALD and MLD techniques in combination with a textile substrate in reinforcing the prospects of wearable thermoelectrics.Peer reviewe

Oxide bulk materials with improved thermoelectric performances by controlling microstructure with sol-gel processing ways

Since decades, thermoelectricity is deeply studied as no-waste energy source. Thermoelectric (TE) materials allow the direct transformation of a heat source into an electrical current (Seebeck effect). TE conversion is very attractive as it is the strongest candidate for producing electricity from waste heat energy sources (automobiles, incinerators, boilers, …). For TE applications at high temperatures, oxide compounds like In2O3, Ca3Co4O9, Bi2Sr2Co2Ox or CaMnO3, have attracted attention, in particular due to their natural oxidation resistance. However, the performances of actual TE oxides must be improved for manufacturing efficient TE generators. For that purpose, an accurate control of micro and nanostructure is required for optimizing the electrical and/or thermal transport properties of TE materials. This can be achieved through the development of innovative powder synthesis techniques, like sol-gel process. In this study, we report on the impact of the use of sol-gel processing techniques on the microstructure (grain size, homogeneity, porosity) of two promising oxide TE compounds and their resulting TE properties. The two studied oxide compounds are the n-type metal doped indium oxide In2-xGexO3 and p-type Bi2Sr2Co2Ox cobaltites