We synthesize heterofluorene monomers with Si, Ge, N, As, Se, and Te occupying the 9-position of the fluorene motif, which are then polymerized by Suzuki coupling. The optical properties of the obtained polymers are investigated in their solid state. We compare and elucidate effects in the materials absorption, emission, quantum yield (Φ), and fluorescence lifetime. Moreover, we determine the refractive indices n and absorption coefficient k by variable angle spectroscopic ellipsometry (VASE). We show that in addition to already known C, Si, and N containing polyfluorenes also Ge and As containing polymers exhibit amplified spontaneous emission.

A series of red fluorescent materials (compounds 1-4), which each contain the symmetric fluorene-thiophene-BT-thiophene-fluorene core, is presented along with their performance in solution-processed OLED devices.Extending the molecular conjugation through end-capping with additional fluorene units (compound 2), or through incorporation of donor functionalities (compounds 3 and 4) improves OLED performance relative to the parent compound 1. Notably, incorporating triphenylamine donor groups in compound 3 led to solutionprocessed OLED devices operating with a peak luminance of 2888 cd m À2 and a low turn-on voltage (3.6 V). † Electronic supplementary information (ESI) available: The graphs for the oxidation and reduction CV cycles of compounds 1-4 are shown in the ESI in Fig. S1-S4, as well as the optical microscope images in Fig. S5, AFM images of unannealed films and films annealed at 80 1C in Fig. S6 and S7 respectively, OLED data at various annealing temperatures of compound 1-4 in Table S1 and 1 H and 13 C NMR spectra for compounds 1-4 in Fig. S8-S15. Supporting data are accessible from http://dx.doi. a Recorded as an average over 8 devices. b Recorded as an average over 4 devices. c Recorded as an average over 6 devices. d Recorded as an average over 3 devices. The best turn on voltages of each compound was recorded without using Alq 3 .

A novel π-conjugated molecule, EtH-T-DI-DTT is reported, which is fused, rigid, and planar, featuring the electron-rich dithieno[3,2-b:2’,3’-d]thiophene (DTT) unit in the core of the structure. Adjacent to the electron-donating DTT core, there are indenone units with electron-withdrawing keto groups. To enable solubility in common organic solvents, the fused system is flanked by ethylhexylthiophene groups. The material is a dark, amorphous solid with an onset of absorption at 638 nm in CH2Cl2 solution, which corresponds to an optical gap of 1.94 eV. In films, the absorption onset wavelength is at 701 nm, which corresponds to 1.77 eV. An ionisation energy of 5.5 eV and an electron affinity of 3.3 eV were estimated by cyclic voltammetry measurements. We have applied this new molecule in organic field effect transistors. The material exhibited a p-type mobility up to 1.33 × 10−4 cm2 V−1 s−1.