Charge transfer and transport properties in PCDTBT/p-nitrobenzylinemalononitrile composite for photovoltaic application

In this study, we investigated the impact of incorporating small organic molecules p-nitrobenzylinemalononitrile (NO₂BMN) into a poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2′,1′,3′-benzothiadiazole] (PCDTBT) matrix on the optical and electrical proprieties. The absorption and photoluminescence spectra were used to confirm the improvement of the optical characteristics. An optimal weight ratio of (1:1) of PCDTBT:NO₂BMN composite is found to achieve the best efficiency of charge transfer that occurs between both compounds. For the same composition, the device based on ITO/PCDTBT:NO₂BMN/Al structure shows an improvement in current density and reduction in threshold voltage. Additionally, we have estimated the conduction mechanisms by the analyses of J (V) characteristics in a double logarithmic scale under dark conditions. The obtained results indicated that the addition of NO₂BMN enhances the electrical properties of the composite.