Synthesis and characterization of a new semiconducting indacenodithiophene-carbazole derivative with interesting optical and electronic properties

Abstract

A novel indacenedithiophene derivative 9,9'-((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(4,1-phenylene))bis(9H-carbazole) (IDT-CB) by a Suzuki coupling reaction was synthesized, its chemical structure was confirmed by 1H-NMR and 13C-NMR, as well as FTIR. Opto-electronic properties were measured in solution and thin solid films through UV-Vis absorbance and photoluminescence (PL) in solution was also determined. UV-Vis absorption was observed at λmax=425 nm, and the optical band gap was 2.59 eV. The HOMO-LUMO frontier orbitals were determined by cyclic voltammetry (CV) with HOMO=−5.9 eV and LUMO=−3.89 eV, then, a band gap of 2.01 eV was estimated. Photoluminescence had a maximum emission at 556 nm. OLED devices were constructed from the compound IDT-CB as emitting layer (EL), with the simple structure glass/ITO/PEDOT:PSS(40 nm)/IDT-CB(52 nm)/FM. Previously, the chemical compound was solubilized in THF at 5 mg/mL and corresponding analyses in thin films and OLED fabrication were carried out. Solution processable yellow-greenish OLEDs were assembled by spin coating with CIE coordinates (0.38, 0.51). J-V plots, as well as luminance, were determined, a turn-on-voltage of 5.76 V and maximum luminance of 1000 cd/m2 were reached.