White Light Generation with Azide Functionalized Polyfluorene Hybridized on Near-UV Light Emitting Diode Ilkem Ozge Huyal, Tuncay Ozel, Sedat Nizamoglu, Unsal Koldemir, Donus Tuncel, and Hilmi Volkan Demir Department of Physics, Department of Chemistry, Department of Electrical and Electronics Engineering Bilkent University, Ankara, Turkey TR-06800 Email: volkan@bilkent.edu.tr Abstract: We present white light generation using poly[(9,9-dihexylfluorene)-co-alt-(9,9-bis-(6- azidohexyl)fluorene] (PFA) for the first time. Hybridizing PFA on near-UV LED, we demonstrate high color rendering index up to 91.0. ©2007 Optical Society of America OCIS codes: (160.4890) Organic materials; (230.3670) Light-emitting diodes Today wavelength-conversion based LEDs are more commonly used in white light generation when compared to multi-chip LEDs and monolithic LEDs [1,2]. In wavelength conversion technique, different coating materials such as phosphors [2], nanocrystals [3,4], and polymers [5] have been used by integrating on pump LED sources. Although phosphor is currently the most popular wavelength-converting material, polymers offer a number of advantages that may possibly make them the future material of choice for white light generation. Polymers have high solid-state photoluminescence (PL) quantum efficiencies; they are easily processed, molecularly engineered and coated using very low-cost techniques [5]. In this work for the first time, we present white light generation (Fig. 1) using poly[(9,9-dihexylfluorene)-co-alt-(9,9-bis-(6-azidohexyl)fluorene] (PFA) hybridized on near-UV (n-UV) InGaN/GaN LEDs (Fig. 2). We experimentally demonstrate white light generation shown in Fig. 1 (a), with high color rendering indices (CRI) using only a single layer of PFA integrated on n-UV LED, as shown on the C. I. E chromaticity diagram [2] in Fig. 1 (b). (a) (b) Figure 1. Our PFA hybridized on n-UV LED: (a) its white light emission and (b) its tristimulus coordinates when the emission is collected from the bottom [►] and the top []. N 3 N 3 * n 300 400 500 600 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Intensity ( /600) Absorbance (a.u.) Wavelength (nm) Absorption Emission 369 416 435 (a) (b) Figure 2. (a) Condensed formula, absorption and PL spectra of PFA. (b) EL spectrum (onset) and a micrograph (inset) of our n-UVLED. At Bilkent University Chemistry Laboratory, PFA is synthesized using Suzuki coupling of 2,7-bis[9,9-bis(6- bromohexyl)-fluorene and 9,9-dihexylfluorene-2,7-bis(trimethyleneborate) under refluxing in a mixture of 2 M Na 2 CO 3 /toluene with Pd(PPh 3 ) 4 as the catalyst [6], followed by excess sodium azide treatment in a2645_1.pdf CMO5.pdf ©OSA 1-55752-834-9