3.5. Powerful charge transport property of DTS structural modification
Among the previously listed studied compounds, the priority should be the electronic properties of the dimer compound. At that biased level, we continuously study the influences of functional groups at 1,1’-positions on DTS-DTS compound 10 , thereby designating four new compounds 10a-10d as shown in Fig. 6.
Similar to the original compound 10 , frontier molecular orbital analysis from 10a-10d has resulted in describing that electrons delocalize over DTS-DTS skeleton in HOMO and LUMO neutral states and slightly visual concentration in pyridyl group in individual10d (Fig. S3). HOMO energies of designated groups10a-10d are comparable to or higher than that of dimer10 , but LUMO and the band gap energies reach to a remarkable order of 10a > 10c >1010b > 10d (Table 5). We can safely manage a good strategy to make lowered LUMO layers and reduce band gap energies, using SiMe3 and C5H3SiMe3 groups at 1,1’-positions.
Considering what λh and λe have acquired so far for charge transport rate. Although the computed values still have better outcomes than CBP , only two significant features can be observed: i) the values λh of designated compounds are scaled down about 2-2.5 folds, relative to originated agent 10 , and ii) the decline has only occurred in the values λe of 10a-10b . Nonetheless, the numerous research that focused on analyzing ionization potential and electron affinity, as compared with compound 10 , the amount of IPv/IPa of 10c-10d is lesser, and compound 10d successfully increases the values EAv/EAa. Generally, structure modification happens at 1,1’-positions of DTS-DTS core which would help to set out to favorable low reorganization energies as expected. Functional groups are reasonable for drastically hole reorganization energies reduction, especially in terms of structural expansion, π-conjugated unit that would help increase electron delocalization and electron transport capacity in oxidative-reductive stable polymeric materials.