A polystyrene bearing perylene diimide pendants with enhanced solid state emission for white hybrid light-emitting diodes

• A copolymer comprising a polystyrene backbone and perylene diimide pendants was synthesized.
• The wide distance of the fluorophores along the chain leads to high solid state PL efficiency.
• This red emitter is successfully used to generate white light in an organic/inorganic hybrid LED.

We report the preparation of a luminescent linear polystyrene decorated with randomly distributed pendants of perylene diimide, where the quenching processes due to aggregation states, typical of perylene diimides, are efficiently suppressed. Compared to a blend with the same polystyrene/dye ratio, the copolymer shows a nearly four-fold increase in quantum efficiency. Stable white emitting devices are straightforwardly prepared by the combination of this red emitting copolymer, a suitable organic green emitter, and an inorganic commercial blue light source. The selected organic dyes have appropriate photophysical characteristics for converting the blue source into a white light emission and exhibit good film forming properties even in the blend. The control of the film thickness of the blended organic dyes along with their relative concentration allows a fine tuning of the color emission. The optimized hybrid white LED displays white emission with chromaticity coordinates of x = 0.31, y = 0.34, a color rendering index of 83 and an efficiency of 28 lm/W.

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