Electrical and optical properties characterization of MEH-PPV thin film using sol-gel method

Abstract

Light-emitting diode (LED) applications consist of various materials. One of the materials used is polymer. In this study, MEH-PPV known as poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1, 4-phenylenevinylene] was used. The objective of this paper is to characterize the electrical and optical properties of MEH-PPV thin film by using sol-gel method. The scope is to study only the MEH-PPV thin film without implementation to any device. The MEH-PPV thin film thicknesses were varied from 10 to 100 nm. The experiment was started by stirring the sol-gel solution with toluene. The spin-coating technique was used to deposit the MEH-PPV thin film on a glass substrate. All samples were characterized using Atomic Force Microscopy (AFM), Surface Profiler, Two-point Probe, Raman PL Dispersive and UV-Vis Spectroscopy for the surface morphologies, thin film thickness, electrical and optical properties respectively. From the current-voltage (I-V) measurement, it show that symmetrical line plotted at low-voltage ranges. Moreover, the calculated conductivity was inversely proportional with the thin film thickness. The results from photoluminescence (PL) spectra showed that the intensity reached optimum peak at 38nm thickness and quenched for other samples. At 108 nm of thickness, absorption reached the highest peak compared to other samples of different thickness. The film was non-uniformed for the thickness at 134 nm, due to aggregation phenomenon.