Fabrication and characterization of an organic light-emitting diode based on Langmuir–Blodgett films using oligo(phenylenevinylene) derivatives

We present the characterization of oligo(phenylenevinylene) derivatives which contain dendrons of first to third generations with terminal chains of C12H25 and C3H7, then, Langmuir–Blodgett and spin coating films of this compounds were used to make an OLED. To make the films, some previous studies were performed such as the isotherms, the Brewster Angle Microscopy and hysteresis to find which compound forms the most suitable monolayer at the water–air interface so that it can be transferred to an ITO-glass substrate through the Langmuir–Blodgett (LB) technique. Until 30 LB films were transferred to ITO and, then, a metallic electrode was deposited over the film to apply a voltage between ITO and this metallic electrode. As a result, a green–yellow organic light-emitting diode was obtained and it was characterized through UV–Vis spectroscopy, photoluminescence, electroluminescence, lifetime and we compared its performance with other OLED fabricated through the spin coating technique. We concluded that the LB OLED has a lower driving voltage and its lifetime is almost the same for both. In addition, we have calculated through density functional theory the band gaps for the six compounds presented here and we observed that all the six dendrons have band gaps of approximately 2 eV.