Optical and dielectrical properties enhancement of composite films based on MEH-PPV matrix and NBD-Cl small organic molecules

Abstract

The solution-processable small organic molecules have provoked the interest for their applications in cost-effective optoelectronic devices. This work presents the incorporation of the small organic molecules of 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) into the MEH-PPV polymer matrix to enhance the performance of charge transport. The absorption and photoluminescence spectra were used to investigate the optical properties of the composite films. An optimal weight ratio of (1:0.5) of MEH-PPV:NBD-Cl is found to achieve the best efficiency of charge transfer. For the same composition, the device based on ITO/MEH-PPV:NBD-Cl/Al shows an improvement in current levels and reduction in threshold voltage. Additionally, by fitting the experimental impedance spectroscopy data, informations about the resistances and mobilities were extracted. The effective charge mobility are 1.62 ×10-3 cm² V−1s−1.