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Improved thermoelectric performance of Ag<inf>2-x</inf>Al<inf>x</inf>Se through formation of AgAl phase
Journal
Applied Physics Letters
ISSN
00036951
Date Issued
2022-10-24
Author(s)
Ahmad, Sajid
Sarkar, Pritam
Bhatt, Pramod
Bhattacharya, Shovit
Navaneethan, M.
Basu, Ranita
Bhatt, Ranu
Bohra, Anil
Debnath, A. K.
Muthe, K. P.
Vitta, Satish
Singh, Ajay
Abstract
Mixed ion-electron conductor Ag2Se is an n-type semiconductor owing to the intrinsic Se vacancies. By reducing Se vacancies, Ag2Se has been demonstrated as a potential environment-friendly thermoelectric material for near room temperature application. In the present work, Al addition was found to be highly beneficial for improving the thermoelectric properties of Ag2Se. In Ag1.95Al0.05Se, a large enhancement in the charge carrier mobility (1127 cm2/V s) is witnessed due to the formation of Se-rich Ag2Se1.02 phase with improved grain connectivity through in situ formed AgAl phase. The synergetic effect of low carrier concentration and enhanced mobility in Al doped samples resulted in a high Seebeck coefficient and high electrical conductivity, leading to a high power factor of 3039 μW/m K2 at 300 K. The figure-of-merit of Ag1.95Al0.05Se was found to be 1.1 at 300 K i.e., 57% higher than for pure Ag2Se. The uni-leg device fabricated using Ag1.95Al0.05Se with electroplated Ni/Ag contacts showed a conversion efficiency of ∼3.2% for a temperature difference of 93 K, i.e., comparable to the best reported value for conventional bismuth telluride.