Fig. 6: Comparison of the activation energy of conductivity and the Seebeck energy.
From: Critical charge transport networks in doped organic semiconductors
a Experimental and calculated activation energy of conductivity of C60:W2(hpp)4 as a function of molar doping ratio. We used an amorphous structure of C60 for the whole range of doping ratios (see Supplementary Table 3 for other parameter values). The excellent agreement of our results with the experimental data shows that the assumption of structural changes upon doping of C60 is not necessary to explain the increase of activation energy at high concentrations, but it can be rationalized solely as the result of electrostatic fluctuations. b Seebeck energy ES of C60:W2(hpp)4 as a function of molar doping ratio. That ES, surprisingly, does not show an increase at high doping concentrations can now be understood: Although the critical hopping energy shows a stronger temperature activation, ES is determined by the average energy of the critical subnetwork with respect to the Fermi level. This average keeps decreasing as the Fermi level moves up in the DOS (see Supplementary Fig. 1 for the DOS plots). Error bars show one standard deviation. Experimental data reproduced from ref. 56, Figs. 3 and 4.
