Investigation of optical and electrical properties of p-nitro-benzylidenemalononitrile thin films for optoelectronic applications

We have successfully synthesized and characterized a donor-bridge-acceptor type conjugated molecule. The absorption and photoluminescence spectra of NO2-benzylidenemalononitrile (NO2-BMN) thin films have been investigated. The NO2-BMN film shows an emission in the visible range, which makes it possible for optoelectronic application. The optical band gap was obtained by the Tauc method from the absorption spectra to be equal to 2.2eV. However the electrochemical gap calculated from cyclic voltammetry is 2.42 eV. Electrical properties of the ITO/NO2-BMN/Al structure was investigated by I-V characteristics. Diode parameters, such as the barrier height ϕb and the ideality factor n were calculated. The conduction is governed by space-charge-limited current (SCLC) mechanism. The effective hole mobility calculated is comparable to that of C60 and 2,7-distyrylcarbazole new molecule (≈10−5 cm2/V). The obtained results of the materials have promising to be applicable for various optoelectronic applications.