  We study role of site substitutions at In and Te site in In2Te5 on the
thermoelectric behavior. Single crystals with compositions In2(Te1-xSex)5 (x =
0, 0.05, 0.10) and Fe0.05In1.95(Te0.90Se0.10)5 were prepared using modified
Bridgman-Stockbarger technique. Electrical and thermal transport properties of
these single crystals were measured in the temperature range 6 - 395 K. A
substantial decrease in thermal conductivity is observed in Fe substituted
samples attributed to the enhanced phonon point-defect scattering. Marked
enhancement in Seebeck coefficient S along with a concomitant suppression of
electrical resistivity \r{ho} is observed in Se substituted single crystals. An
overall enhancement of thermoelectric figure of merit (zT) by a factor of 310
is observed in single crystals of Fe0.05In1.95(Te0.90Se0.10)5 compared to the
parent In2Te5 single crystals.
