Photoinduced photoluminescence intensity enhancement in poly(p-phenylene vinylene) films

Abstract

Articles you may be interested inMorphology and chain aggregation dependence of optical gain in thermally annealed films of the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene]

Statistical Analysis in Homopolymeric Surfaces

“…14 shows the non-irradiated (NI) and irradiated (I) regions, clearly distinguishable in the AFM image, which was obtained by using a CCD camera coupled to the microscope, using the illumination in the transition setup. The majority of the light was transmitted in the irradiate region (I), in agreement with the absorption spectra (Gobato et al, 2002). In this macroscopic scale, the image shows qualitatively low non-homogeneity in both surface regions, with morphological defects (peaks) distributed randomly on the surface.…”

“…The presence of chemical structure degradation is evident in the absorption of the UV-Vis range and infrared (IR) measurements reported by Gobato et al, 2002. After light exposure, the absorption spectrum is blue shifted and the IR spectrum presents a major increase in 1690 cm -1 peak, identified as the carbonyl group (C=O) incorporation (Barford & Bursill, 1997;Chandross et al, 1994;Friend, et al, 1997;Onoda et al, 1990).…”

“…Surface topology of organic flexible materials is generally controlled by a chemical and physical process, the polymer coatings are generally heterogeneous, and the most significant changes occur in the nanometer scale (Gobato et al, 2002). The Atomic Force Microscopy (AFM) technique, in special, has made significant experimental contributions to three-dimensional imaging with high-resolution in a subnanometer scale, without specific sample preparation (Bar et al, 1998;Binnig et al, 1986;Gua et al, 2001).…”

Photophysics of poly(p-phenylene vinylene) films

“…The increase of the infrared peak related to carbonyl group C=O stretch at 1690 cm −1 suggests that a photo-oxidative reaction with carbonyl formation occurs during the PL enhancement process. The PL enhancement process depends strongly on the experimental constraints used, i.e., the ratio d/λ o between sample thickness (d) and light penetration depth (λ o ), which imposes a geometric limit for the defect formation and the carrier recombination [10]. The PL enhancement observed for film thickness d ≥ λ o could be explained as follows.…”

“…This effect has been ascribed to the creation of carbonyl groups. However, PL intensity enhancement induced by a proper laser irradiation has been recently demonstrated in a PPV cast film [10]. This effect can be understood in terms of the chain shortening process due to carbonyl incorporation and formation of an energy profile that extends and migrates into the film and enables efficient spectral diffusion of excited carriers to a non-degraded PPV layer.…”