Table 3. Calculated E_L–H, First Singlet Excitation Energy (E_opt), and Binding Energy (E_b)^a.

compounds	EL–H	Eopt	Eb
DBTR	3.070	2.436	0.634
DBTD1	2.497	2.175	0.322
DBTD2	2.359	2.097	0.262
DBTD3	2.222	2.010	0.212
DBTD4	2.196	2.014	0.182
DBTD5	2.138	1.966	0.172
DBTD6	2.131	1.980	0.151

^aUnits in eV.