Recently developed star‐shaped nanosized oligofluorene truxenes are dispersed in a novel vinyl ether based photoresist to produce microstructures via direct laser writing. The technique offers rapid and facile production of nanostructures whithin a microstructure, and ensures environmental protection from photo‐oxidation of the fluorescent molecules.
We report on an approach to ultraviolet (UV) photolithography and direct writing where both the exposure pattern and dose are determined by a complementary metal oxide semiconductor (CMOS) controlled micro-pixellated light emitting diode array. The 370 nm UV light from a demonstrator 8 x 8 gallium nitride micro-pixel LED is projected onto photoresist covered substrates using two back-to-back microscope objectives, allowing controlled demagnification. In the present setup, the system is capable of delivering up to 8.8 W/cm2 per imaged pixel in circular spots of diameter approximately 8 microm. We show example structures written in positive as well as in negative photoresist.
We report on the integration of monodisperse semiconductor nanocrystal (NC) color converters onto gallium nitride ultraviolet micro-pixelated light-emitting diodes ('micro-LEDs'). Integration is achieved in a 'self-aligned' process by forming a nanocomposite of the respective NCs in a photocurable epoxy polymer. Blue, green, yellow and red NC/epoxy blend microstructures have been successfully integrated onto micro-pixelated LEDs by this technique and utilised for color conversion, resulting in a five color emission single chip. Optical output power density of up to about 166 mW/cm2 is measured; spectral emission at 609 nm gives an estimated optical-to-optical conversion as high as 18.2% at 30 mA driving current.
Fluorescent nanostructures within a transparent microstructure can be achieved via direct laser writing. , Alexander Kuehne, Peter Skabara, Martin Dawson, Richard Pethrick, and co‐workers report on a novel UV‐transparent photoresist that incorporates star‐shaped nanometer‐sized oligofluorene truxenes. The method and materials will find applications in optical, electro‐optical, and photonic devices. (Cover artwork by Leif Heuser).
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