First principle studies in PEDOT:PSS, PPP and PPV layers for OLED application

The electrical properties of Poly (3,4 ethylene dioxy- thiophene) (PEDOT) as a hole transporting polymer in organic light-emitted devices (OLEDs) is investigated. The distribution of molecular orbitals and the density of electronic states were studied and the energy gap of PEDOT’s octamer was calculated using B3LYP method by means of Gaussian03W software. In addition, the electrical and optical properties of poly para-phenylene (PPP) and poly para-phenylene vinylene (PPV) as an active layer in OPVs were calculated. The simulation was performed based on density functional theory (DFT) by means of SIESTA package. The electrical band structure and the imaginary part of dielectric function and its relation to the photoluminescence spectra and optical band gap were studied.