Abstract
Due to the unique structures of helicenes, we aim to probe their prospective as proficient optoelectronic and charge transfer materials. With the intention to shed light on both at the molecular and bulk levels various properties of interest have been studied. The optical (refractive indices, reflectivity, conductivity, absorption, dielectric constant and extinction coefficient) and electronic properties (total/partial density of states (T/PDOS) of some recently synthesized diquaternary salts of 4,4'-bipyridine helical viologens, i.e., 5,10-dimethyl-5,10-diaza[ 5] helicene bis-tetrafluoroborate 1(2+) (Compound1) and 3,8-dimethyl-3,8-diaza[5] helicene bis-tetrafluoroborate 2(2+) (Compound2) at the bulk level in solid-state have been reflected. The balanced values of hole and electron electronic coupling (V-h and V-e) for compound1 disclose that it might be good ambipolar material. For Compound2 V-e is greater than Vh enlightening that it might be good electron transfer contender. Furthermore, the electronic, photophysical (absorption, fluorescence, phosphorescence) and charge transfer properties (ionization potential (IP), electron affinity (EA) and hole/electron reorganization energy (lambda(h)/(e)) of their bipyridine precursors (Compound3 and Compound4) as well as redox partners of Compound1 and Compound2 which are neutral forms of 1(2+) and 2(2+) named Compound5 and Compound6, respectively have been explored. The band gap, DOS, dielectric function, conductivity and refractive indices, IP, EA and lambda(h)/(e) values revealed that these diaza[5] helicenes would be good contenders to be used in semiconductor devices. The dielectric functions also revealed that Compounds 1 and 2 retain energy holding ability which these systems absorb. It is also expected that absorption capability of photons would be enhanced in studied compounds especially Compounds 5 and 6 having narrow band gaps.