Spectral narrowing phenomena in the emission from a conjugated polymer

• Published in: Optical materials Vol. 9; no. 1; pp. 70 - 76
• Main Authors: Long, X., Grell, M., Malinowski, A., Bradley, D.D.C., Inbasekaran, M., Woo, E.P.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 1998; Elsevier Science
• Subjects: Applied sciences; Conjugated polymer; Electrical, magnetic and optical properties; Exact sciences and technology; Film morphology; Fundamental areas of phenomenology (including applications); Interchain interaction; Optical materials; Optics; Organic polymers; Physicochemistry of polymers; Physics; Polymers and organics; Properties and characterization; Spectral narrowing; Conjugated polymer; Spectral narrowing; Interchain interaction; Film morphology; Heat treatment; Line narrowing; Spectral line profile; Photoluminescence; Ultraviolet spectrum; Spin-on coating; Experimental study; Liquid crystals; Absorption spectrum; Thin film
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/S0925-3467(97)00157-2

We report a study of the morphology dependent emission properties of a liquid crystalline polyfluorene in solid thin films. Spectral narrowing (SN) is observed in spin coated films, but after thermal treatment of the same films the SN is no longer observed. For films which are spin coated on a rubbed polyimide alignment layer, the situation is different. There is then no influence of thermal treatment on the observation of SN. However, specific combinations of the pump polarization direction, film alignment direction and the long axis of the rectangular excitation area now play an important role. The spectral location of SN peaks also varies with film morphology and for different regions of the same sample. The occurrence of SN is strongly dependent on film morphology and the excitation configuration.