There is a growing demand to improve the operational lifetime of electroluminescent devices utilizing conjugated polymers which are often deposited over metal electrodes. Photo-degradation of the emissive organic layer is one factor that decreases the overall efficiency and longevity of these devices. Therefore, it is important to investigate the underlying photochemistry at metal-polymer interface. Here, the effects of metal films on the emission properties of organic polymers are studied using Total Internal Reflection Fluorescence (TIRF) microscopy and Fluorescence Lifetime Imaging (FLIM). Poly(phenylene vinylene) (MEHPPV) is spun cast over gold films of varying thickness (2 nm to 8 nm). Whereas 8 nm gold films completely quench the MEHPPV fluorescence, thinner gold films (~ 2 nm) cause minimal quenching. However, deposition on the thinner gold films leads to a dramatic increase in photo-stability of MEH-PPV relative to that on glass, even in the presence of molecular oxygen and under continuous laser illumination. Good overlap between the surface plasmon absorbance of gold films and the emission of MEHPPV is required for this effect as it is not observed on metals without a plasmon band in this spectral region.

Date Published: 24 August 2017
PDF: 6 pages
Proc. SPIE 10348, Physical Chemistry of Semiconductor Materials and Interfaces XVI, 103481M (24 August 2017); doi: 10.1117/12.2274306

Published in SPIE Proceedings Vol. 10348:
Physical Chemistry of Semiconductor Materials and Interfaces XVI
Hugo A. Bronstein; Felix Deschler, Editor(s)