P-nitro-benzylidenemalononitrile molecule importance in the enhancement of the optical and the electrical properties of thin film based on PVK for optoelectronic applications

Abstract

For the first time, p-nitro-benzylidenemalononitrile was integrated in Poly(9-vinylcarbazole) (PVK) P-type polymer. The UV–Vis spectra showed an enhancement of the optical response of the composite related to a π–π interaction that occurs between conjugated systems of carbazole groups and NO2BMN molecules. The Photoluminescence curves showed a significant quenching that is related to the charge transfer phenomenon occurring between donor and acceptor compounds. The electrical response revealed that the PVK: NO2BMN composite had a diode behavior. Thus, the electrical parameters improved upon the addition of NO2BMN. The capacitance exhibited Mott–Schottky behaviour, indicating the formation of a Schottky junction (band bending) at the PVK: NO2BMN/Al interface. The interface state density Nss and trap state’s time constant values τ of PVK and PVK: NO2BMN were [1.406 (1014 eV−1 m−2), 0.77 µs] and [1.321 (1014 eV−1 m−2), 0.10 µs], respectively. This result was compared to the literature and showed that the NO2BMN enhances the composite performance. From capacitance, the built-in potential and the minority charges concentrations were calculated for the composite. We found the values of Vbi = 2.6 V and NA = 3.49 (1016 cm−3).