Printed Lateral p–n Junction for Thermoelectric Generation

Abstract

Printed thermoelectric generators (TEGs) show promising potential for converting waste heat into useful electricity at a low cost but fall short of exhibiting a conversion efficiency anticipated from materials’ properties. The output power of conventionally printed TEGs in the “π‐type” geometry suffers due to low thermal voltage and low current because of high thermal and electrical contact resistance, respectively. Herein, a type of printed p–n junction TEGs (PN‐TEGs) as a possible remedy is explored. Two printed PN‐TEGs with different thicknesses are fabricated using printed p‐type Bi0.5Sb1.5Te3 and n‐type Bi2Te2.7Se0.3 materials. The PN‐TEGs show a promising way to minimize the influence of thermal and electrical resistance in printed TEGs. In the experimental and simulation results, the significant impact of PN‐TEGs’ dimensions on their power outputs is revealed. Also, a conventional “π‐type” printed TEG is fabricated and its performance is studied. The optimized PN‐TEG with a single thermocouple yields ≈14 times higher power output density of 5.3 μW cm−2 at a ΔT of 25 K compared to “π‐type” printed TEGs.