*3.3.4. Sn0.99Mn0.01Se*

For SnSe doped with 1% manganese (**Figure 9b**), we also find an abrupt change of sign of the Seebeck coefficient, as described above for Sn0.9Y0.1Se. However, for Mn-doped SnSe the thermoelectric power is positive at low temperatures, and inverts above 630 K. A similar explanation considering two types of charge carriers may be invoked here. Importantly, this behavior is intrinsic to the material, not an effect of thermally induced chemical changes, as it is reversible, and reproducible in several thermal cycles. Therefore, Mn-doping provides a high temperature n-type SnSe thermoelectric element.
