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[12p-A407-4] Tuning the thermoelectric property of flexible Ag2S material by
non-toxic transition metal substitution
Keywords:Chalcogenides, Thermoelectrics, Flexible thermoelectric
To fabricate thermoelectric (TE) generators for alternate source of energy, which can supply an input power (microW to mW) to many sensors, electronic gadgets, and wearable devices in low temperature range around 300 – 400
K [1] are a major focus of industrial research. Improvement of figure of merit, ZT, of the TE materials used in such
devices is very important. Besides, if these materials are flexible [2], the number of applications would be significantly
enlarged.
Recently, Ag2S is found to be an interesting material, as near room temperature it possesses good flexible
properties with very low thermal conductivity (~ 0.5 W/m K) and large Seebeck coefficients (~ –900 microV/K) [3].
However, due to large electrical resistivity (~ 103 ohm cm), the value of ZT was found to be very low. To improve the
ZT, the substitutions of Se, Te at sulfur site are investigated [4,5]. Although significant enhancement in ZT is achieved
but limited to n-type only. Besides, it contains the toxic elements, therefore it is not appropriate to make the flexible
TE devices used for human body. To overcome these problems, modification in electronic structure of Ag2S is of
crucially importance. For such a purpose, partial substitution at the Ag site can play an important role. Investigations
using this approach have not been widely performed yet, and its comprehensive study is required. Therefore, we
carried the electronic structure calculations on Ag2-xTMxS (TM = transition metal element using DFT, and successfully
achieved both p and n-type TE property of these material experimentally.
K [1] are a major focus of industrial research. Improvement of figure of merit, ZT, of the TE materials used in such
devices is very important. Besides, if these materials are flexible [2], the number of applications would be significantly
enlarged.
Recently, Ag2S is found to be an interesting material, as near room temperature it possesses good flexible
properties with very low thermal conductivity (~ 0.5 W/m K) and large Seebeck coefficients (~ –900 microV/K) [3].
However, due to large electrical resistivity (~ 103 ohm cm), the value of ZT was found to be very low. To improve the
ZT, the substitutions of Se, Te at sulfur site are investigated [4,5]. Although significant enhancement in ZT is achieved
but limited to n-type only. Besides, it contains the toxic elements, therefore it is not appropriate to make the flexible
TE devices used for human body. To overcome these problems, modification in electronic structure of Ag2S is of
crucially importance. For such a purpose, partial substitution at the Ag site can play an important role. Investigations
using this approach have not been widely performed yet, and its comprehensive study is required. Therefore, we
carried the electronic structure calculations on Ag2-xTMxS (TM = transition metal element using DFT, and successfully
achieved both p and n-type TE property of these material experimentally.