Influence of Doped Poly(N-vinylcarbazole) on Poly(3-octylthiophene) Electroluminescence

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Abstract
Organic electroluminescent (EL) cells with one layer of poly(3-octylthiophene) (P3OT) doped with various amounts of poly(N-vinylcarbazole)(PVK)(P3OT/PVK) as the EL-emitting layer sandwiched between indium/tin-oxide (ITO) and aluminium electrodes have been fabricated by spin coating onto ITO. It was found for the first time that although the resistance of ITO and the work function of the aluminium electrode are high, the (P3OT/PVK) EL cell emits visible red-orange light with the optimum molar ratio of P3OT to PVK at 5 V which corresponds to a current density as low as 30 mA/cm2. However, the luminance and the current density of the P3OT/PVK EL cells at the same bias voltage change with varying molar ratios of P3OT to PVK, indicating that the PVK dopant influences the P3OT electroluminescence. It was proven that an optimum molar ratio must exist among these various molar ratios of P3OT to PVK in the emitting layer.