Thermoelectric generator based on a bismuth-telluride alloy fabricated by addition of ethylene glycol

• Bi–Te composition ratio is controlled by the addition of ethylene glycol (EG).
• N-type and p-type thermoelectric materials are selectively formed by EG addition.
• N-type when EG is under 20%v/v turned to p-type when EG is greater than 20%v/v.
• Thermoelectric generators (TEGs) were fabricated using p-type and n-type Bi–Te.
• Output powers of the TEGs increased linearly with the number of thermocouples.

This paper introduces a new method to selectively fabricate n-type and p-type bismuth (Bi)-telluride (Te) thermoelectric materials by the rate of addition of ethylene glycol (EG) in the Bi–Te co-electrodeposition solution. As the amount of added EG is increased, the atomic ratio of Bi in the deposited Bi–Te alloy reached a slope of 0.463 (at.% of Bi/vol.% of EG), and increased in a linear manner. When the EG content reached approximately 20%v/v, the n-type material changed into a p-type. This change implies that adjusting the EG content in the electrodeposition solution affords simple control of the Bi–Te composition. To demonstrate the applicability of the developed thermoelectric materials, thermoelectric generators (TEGs) were fabricated using electrodeposited n-type (using solution without EG) and p-type (using solution with 30%v/v EG) Bi–Te alloys. The Seebeck voltage of the pair of n-type and p-type thermoelectric materials was 140 mV and the power generated from the pair was 24.36 nW at a 10 °C temperature difference.