Regular papers

Evidence for the Double Excimer State of conjugated polymer in a liquid solution

¹ Al-Imam Mohammed bin Saud Islamic University, Physics Department, College of Science P.O. Box 90950, Riyadh 11623, Saudi Arabia
² KSU Research Chair on Laser Diagnosis of Cancers, King Saud University, Physics Department and Astronomy, College of Science, Riyadh 11623, Saudi Arabia
³ Al-Imam University, Physics Department, College of Science P.O. Box 90950, Riyadh 11623, Saudi Arabia

^* masila123@gmail.com

Received: 9 June 2012
Revised: 5 October 2012

Abstract

In this paper, the spectral properties of a conjugated polymer poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) in benzene have been studied. The results showed that the fluorescence spectra of MEH-PPV under low concentrations had two peaks; the dominant one due to monomer was around 560 nm, and the shoulder one attributed to the excimer was around 600 nm. Under higher concentrations, it was found that there was only one band around 600 nm due to the excimeric state. By increasing the concentrations of MEH-PPV, it could be seen that there was a new band around 640nm. This band is being attributed to the double excimer. Under high power pulsed laser excitation, we observed amplified spontaneous emission (ASE) at 570 nm, 605 nm and 650 nm. These ASE peaks could arise from the monomer, excimer and double excimer states of the macromolecule respectively. To the best of our knowledge this is perhaps the first report on ASE from double excimer of the conjugated polymer, MEH-PPV in liquid solution.