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

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 N_ss 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 V_bi = 2.6 V and NA = 3.49 (1016 cm⁻³).