Physical Properties of MEH-PPV Thin Films at Different Ageing

Poly (2-methoxy-5(2’-ethylhexyloxy)-phenylene vinylene) (MEH-PPV) thin films were deposited by spin-coating technique. The MEH-PPV powders were dissolved in toluene solution. In this study, we report the effect of ageing on electrical and optical properties MEH-PPV thin films. The thickness of MEH-PPV increased as ageing time increased. The electrical properties were obtained using 2-point probe. The resistivity of thin films decreased as ageing time increased and vice versa with conductivity. The optical properties were investigated using UV-Visible-NIR (UV-VIS-NIR) and atom force microscope (AFM). From UV-Vis result shows the lower band gaps of films in toluene solution proved MEH-PPV has longer conjugation segments. The surface roughness of thin films decreased with the increased of ageing time; which is caused by the aggregation of the MEH-PPV. The PL spectra show the quenching of emission might be due to the conjugation of length polymer changes in different ageing times.