Optical band gaps of organic semiconductor materials

UV-Vis can be used as an easy and forthright technique to accurately estimate the band gap energy of organic pi-conjugated materials, widely used as thin films/composites in organic and hybrid electronic devices such as OLEDs, OPVs and OFETs. The electronic and optical properties, including HOMO-LUMO energy gaps of pi-conjugated systems were evaluated by UV-Vis spectroscopy in CHCl3 solution for a large number of relevant pi-conjugated systems: tris-8-hydroxyquinolinatos (Alq(3), Gaq(3), Inq(3), Al(qNO(2))(3), Al(qCl)(3), Al(qBr)(3), In(qNO(2))(3), In(qCl)(3) and In(qBr)(3)); triphenylamine derivatives (DDP, p-TTP, TPB, TPD, TDAB, m-MTDAB, NPB, alpha-NPD); oligoacenes (naphthalene, anthracene, tetracene and rubrene); oligothiophenes (alpha-2T, beta-2T, alpha-3T, beta-3T, alpha-4T and alpha-5T). Additionally, some electronic properties were also explored by quantum chemical calculations. The experimental UV-Vis data are in accordance with the DFT predictions and indicate that the band gap energies of the OSCs dissolved in CHCl3 solution are consistent with the values presented for thin films. (C) 2016 Elsevier B.V. All rights reserved.