We can also compare the orbital energies between Npe:TCNB and Npe:TCNQ using an analysis based on Koopman's theorem to assess the degree of S0 CT, estimating that the EA is approximately equal to the negative of the LUMO energy. This gives an EA TCNB of 3.04 eV vs. an EA TCNQ of 3.98 eV. Comparing the estimations of EA to calculations of ground state CT using an NBO analysis, we observe that Npe:TCNB exhibits smaller degree of CT, 0.02e, vs. 0.04e in Npe:TCNQ, as expected from TCNB's smaller EA.