The importance of temperature dependent energy gap in the understanding   of high temperature thermoelectric properties
  In the present work, we show the importance of temperature dependent energy band gap, E$_{g}$(T), in understanding the high temperature thermoelectric (TE) properties of material by considering LaCoO$_{3}$ (LCO) and ZnV$_{2}$O$_{4}$ (ZVO) compounds as a case study. For the fix value of band gap, E$_{g}$, deviation in the values of $\alpha$ has been observed above 360 K and 400 K for LCO and ZVO compounds, respectively. These deviation can be overcomed by consideration of temperature dependent band gap. The change in used value of E$_{g}$ with respect to temperature is $\sim$4 times larger than that of InAs. This large temperature dependence variation in E$_{g}$ can be attributed to decrement in the effective on-site Coulomb interaction due to lattice expansion. At 600 K, the value of \textit{ZT} for \textit{n} and \textit{p-doped}, LCO is $\sim$0.35 which suggest that it can be a used as a potential material for TE device. This work clearly suggest that one should consider the temperature dependent band gap in predicting the high temperature TE properties of insulating materials. 
Saurabh Singh and Sudhir K. Pandey
cond-mat.str-el