Abstract
In this study, novel copolymers consisting of blue and red chromophores are presented to induce emission tuning, enabling the definition of white light emission in a single polymeric layer. These aromatic polyether sulfones exhibit high molecular weights, excellent solubility and processability via solution deposition techniques. In addition, by carefully controlling the molar ratios of chromophores composition, the energy transfer mechanism, from blue to red chromophores, takes place enabling us to define properly the emission covering the entire range of the visible spectrum. The optical and photophysical properties of the monomers and copolymers were thoroughly investigated via NIR-Vis-far UV Spectroscopic Ellipsometry (SE), Absorbance and Photoluminescence (PL). These copolymers are used as an emissive layer and applied in solution-processed WOLED devices. The fabricated WOLED devices have been subsequently studied and characterized in terms of their electroluminescence properties. Finally, the WOLED devices possess high color stability and demonstrate CIE Coordinates (0.33, 0.38), which approach closely the pure white light CIE coordinates.
Highlights
In recent years, tremendous advances in the field of Polymer Light-Emitting Diodes (PLEDs) have been achieved mainly through the synthesis of novel emitting materials and the development of improved device architectures [1,2,3,4,5]
This approach has been thoroughly investigated in the past by our group, showing excellent results over the preparation of conjugated polymers carrying different chromophores interrupted by aliphatic flexible spacers of high molecular weights, excellent film forming ability and solubility in organic solvents, control and fine-tuning of the emission light and increased thermal and mechanical stability [4,9,18,20]
We have demonstrated the fabrication of solution-processed White Organic Light-Emitting Diodes (WOLEDs) (ITO/ PEDOT: PSS/Copolymers/Ca/Ag) with the single-emissive layer structure based on novel copolymers bearing blue and red chromophores
Summary
Tremendous advances in the field of Polymer Light-Emitting Diodes (PLEDs) have been achieved mainly through the synthesis of novel emitting materials and the development of improved device architectures [1,2,3,4,5]. Scientific interest has largely increased in White Organic Light-Emitting Diodes (WOLEDs) processed from wetbased techniques, which have strong potential for use in future solid-state light sources and flat panel displays [1,2,3,4,5,6,7,8,9]. A variety of approaches based on semiconductor polymers, as the active layer of wetprocessed OLEDs, have been proposed for the realization of white light emission [5]. Most of the WOLED devices reported so far have relied on the use of combinations of several organic components in blended systems or heterolayer architectures that emit different colors to fully span the entire visible spectrum [5]. The preparation of such blended or heterolayer devices is more complicated; in the case of blended systems, there is
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