Development offlexible thermoelectric device: Improvement ofdevice performance

Thermoelectric (TE)device hassomeproblems, suchas lowmechanical strength, highmanufacturing cost, etc. We aredeveloping flexible TE device usingthinfilmsand flexible substrates inorder toovercome those problems. Thepurpose ofthis workistofabricate andevaluate the flexible TEdevice. A flexible TEdevice consists ofvapordeposited thinfilms ofn-andp-type TEmaterials between twoflexible substrates. Theflexible substrate ismadeupofa combination ofpolyimide andcopper. Thisstructure enables thedevice itself toconvert temperature difference ofouter surfaces (ATO1t) intoin-plane temperature difference (ATiT), anditcangenerate electricity bythep-ncouples. We analyzed temperature distribution ofthedevice bythefinite element method (FEM). According totheanalysis, aflexible substrate whichhasthinner polyimide layer (h1) andthicker copper layer (h2) ispreferable toobtain larger temperature difference. We fabricated flexible TEdevices containing 33 pairs ofp-ncouple, whichiscomposed ofchromel and constantan thinfilms. Thedevice ofh1/h2=124m/70im generated 3.724WatATO,t=22.7K, while2.40tWwas generated fromthedeviceof hj/h2=35 im/25 im at ATO,t=24.OK. Theperformance oftheflexible TEdevice was successfully improved aspredicted bytheanalysis.