Investigation of efficiency and photostability in polymer films

The photodegradation mechanism and luminescence efficiency of a series of thin polymer films prepared under a variety of conditions was studied. The conjugated polymer, poly(m-phenylene-co-2,5-dioctoxy-p-phenylenevinylene), is shown by infrared spectroscopy to degrade via the chain scission of the carbon double bond along the polymer backbone. To reduce photodegradation effects films were prepared using argon (Ar) gas and were investigated in air and an oxygen free environment. The initial photolumiscence (PL) efficiency increased by 70% for Ar treated films. The PL decay in air was bi-exponential in nature, with a sharp initial decay linked to atmospheric oxygen and a longer second decay linked to oxygen embedded in the film. This novel preparation technique coupled with device encapsulation should significantly improve both device efficiency and lifetime.