Carrier deep-trapping mobility-lifetime products in poly(p-phenylene vinylene)

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Abstract
In order to estimate the deep‐trapping mobility‐lifetime (μτ) product for holes and electrons in poly(p‐phenylene vinylene) (PPV), trap‐free space‐charge‐limited current, and time‐of‐flight measurements were performed on bilayer devices comprising of a PPV layer and a trap‐free molecularly doped polymer layer. μτ products of about 10−9 and 10−12 cm2/V were found for holes and electrons respectively, corresponding to an average range of 1 μm for holes and 10 Å for electrons under an electric field of 105 V/cm. The low μτ value for electrons is attributed to severe deep trapping of electrons in PPV, which effectively reduces their range. Implications on the efficiency of electroluminescence devices are discussed.