where L is the Lorentz number. As a result, the κ el rises with n, and the fall in σ with temperature and compensating T term in Eq. 3 leads to a relatively flat variation with temperature. This results in relatively large κ el for p-doped Bi 2 TeO 2 and all three n-doped systems, which will offset the higher PFs in the thermoelectric figure of merit (c.f. Eq. 1).