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Microfluidic White Organic Light-Emitting Diode Based on Integrated Patterns of Greenish-Blue and Yellow Solvent-Free Liquid Emitters.

Kobayashi N, Kasahara T, Edura T, Oshima J, Ishimatsu R, Tsuwaki M, Imato T, Shoji S, Mizuno J - Sci Rep (2015)

Bottom Line: The fabricated electro-microfluidic device successfully exhibited white electroluminescence (EL) emission via simultaneous greenish-blue and yellow emissions under an applied voltage of 100 V.A white emission with Commission Internationale de l'Declairage (CIE) color coordinates of (0.40, 0.42) was also obtained; the emission corresponds to warm-white light.The proposed device has potential applications in subpixels of liquid-based microdisplays and for lighting.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Science and Engineering, Waseda University 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.

ABSTRACT
We demonstrated a novel microfluidic white organic light-emitting diode (microfluidic WOLED) based on integrated sub-100-μm-wide microchannels. Single-μm-thick SU-8-based microchannels, which were sandwiched between indium tin oxide (ITO) anode and cathode pairs, were fabricated by photolithography and heterogeneous bonding technologies. 1-Pyrenebutyric acid 2-ethylhexyl ester (PLQ) was used as a solvent-free greenish-blue liquid emitter, while 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb)-doped PLQ was applied as a yellow liquid emitter. In order to form the liquid white light-emitting layer, the greenish-blue and yellow liquid emitters were alternately injected into the integrated microchannels. The fabricated electro-microfluidic device successfully exhibited white electroluminescence (EL) emission via simultaneous greenish-blue and yellow emissions under an applied voltage of 100 V. A white emission with Commission Internationale de l'Declairage (CIE) color coordinates of (0.40, 0.42) was also obtained; the emission corresponds to warm-white light. The proposed device has potential applications in subpixels of liquid-based microdisplays and for lighting.

No MeSH data available.


(a) Photographic image of the microfluidic WOLED under a 365-nm UV irradiation. (b) EL spectrum of the microfluidic WOLED under an applied voltage of 100 V. (c) CIE coordinates of the microfluidic OLEDs with PLQ and TBRb-doped PLQ, and the microfluidic WOLED.
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f5: (a) Photographic image of the microfluidic WOLED under a 365-nm UV irradiation. (b) EL spectrum of the microfluidic WOLED under an applied voltage of 100 V. (c) CIE coordinates of the microfluidic OLEDs with PLQ and TBRb-doped PLQ, and the microfluidic WOLED.

Mentions: Figure 5(a) shows a photographic image of the fabricated microfluidic WOLED. The liquid light-emitting layers were simply formed by alternately injecting the greenish-blue and yellow liquid emitters from the inlets into the 60-μm-wide microchannels. The liquid emitters were excited with a 365-nm UV lamp, which was introduced through the glass substrate of the microfluidic WOLED. The PLQ and TBRb-doped PLQ patterns were confirmed in the fabricated device without leakage at the bonded interface between the anode and cathode substrates. Therefore, the proposed fabrication methodology for the microfluidic WOLED is effective for realizing the integrated sub-100-μm wide liquid-emitting layers on a single device. The photographic image shown in Fig. 5(b) is the microfluidic WOLED under an applied voltage of 100 V. It can be clearly seen that white EL emission was successfully produced by the microchannels sandwiched between the GOPTS-modified ITO anode and APTES-modified ITO cathode. As shown in Fig. 5(b), the obtained spectrum was found to be composed of a greenish-blue emission band from PLQ and a yellow emission band from TBRb-doped PLQ. As a result, the microfluidic WOLED having the integrated PLQ and TBRb-doped PLQ patterns exhibited a broad emission band that covers the visible-light wavelength ranging from 420 nm to 750 nm Furthermore, the obtained spectrum shows that the yellow component was higher than the greenish-blue one at the applied voltage of 100 V; this is similar to EL spectra from the 1000-μm-wide electro-microfluidic device [see also Fig. 3(b)]. Thus, the excitons of greenish-blue and yellow emitters were successfully produced from the integrated 60-μm-wide microchannels as well as the 1000-μm-wide microchannels. CIE coordinates of the greenish-blue, yellow, and white-light emission under the applied voltage of 100 V are shown in Fig. 5(c). The obtained CIE coordinates of the 1000-μm-wide electro-microfluidic devices with PLQ and TBRb-doped PLQ at 100 V were (0.16, 0.26) and (0.49, 0.47), respectively. The microfluidic WOLED through the simultaneous greenish-blue and yellow emissions showed the CIE coordinates of (0.40, 0.42) at 100 V, which is within the white region and nearly corresponds to warm-white27. White balance of our microfluidic WOLED can be simply tuned by varying microchannel-width ratios for greenish-blue and yellow liquid emitters (see Fig. S1). This color-tunable characteristic with microfluidic technologies is an innovative property.


Microfluidic White Organic Light-Emitting Diode Based on Integrated Patterns of Greenish-Blue and Yellow Solvent-Free Liquid Emitters.

Kobayashi N, Kasahara T, Edura T, Oshima J, Ishimatsu R, Tsuwaki M, Imato T, Shoji S, Mizuno J - Sci Rep (2015)

(a) Photographic image of the microfluidic WOLED under a 365-nm UV irradiation. (b) EL spectrum of the microfluidic WOLED under an applied voltage of 100 V. (c) CIE coordinates of the microfluidic OLEDs with PLQ and TBRb-doped PLQ, and the microfluidic WOLED.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f5: (a) Photographic image of the microfluidic WOLED under a 365-nm UV irradiation. (b) EL spectrum of the microfluidic WOLED under an applied voltage of 100 V. (c) CIE coordinates of the microfluidic OLEDs with PLQ and TBRb-doped PLQ, and the microfluidic WOLED.
Mentions: Figure 5(a) shows a photographic image of the fabricated microfluidic WOLED. The liquid light-emitting layers were simply formed by alternately injecting the greenish-blue and yellow liquid emitters from the inlets into the 60-μm-wide microchannels. The liquid emitters were excited with a 365-nm UV lamp, which was introduced through the glass substrate of the microfluidic WOLED. The PLQ and TBRb-doped PLQ patterns were confirmed in the fabricated device without leakage at the bonded interface between the anode and cathode substrates. Therefore, the proposed fabrication methodology for the microfluidic WOLED is effective for realizing the integrated sub-100-μm wide liquid-emitting layers on a single device. The photographic image shown in Fig. 5(b) is the microfluidic WOLED under an applied voltage of 100 V. It can be clearly seen that white EL emission was successfully produced by the microchannels sandwiched between the GOPTS-modified ITO anode and APTES-modified ITO cathode. As shown in Fig. 5(b), the obtained spectrum was found to be composed of a greenish-blue emission band from PLQ and a yellow emission band from TBRb-doped PLQ. As a result, the microfluidic WOLED having the integrated PLQ and TBRb-doped PLQ patterns exhibited a broad emission band that covers the visible-light wavelength ranging from 420 nm to 750 nm Furthermore, the obtained spectrum shows that the yellow component was higher than the greenish-blue one at the applied voltage of 100 V; this is similar to EL spectra from the 1000-μm-wide electro-microfluidic device [see also Fig. 3(b)]. Thus, the excitons of greenish-blue and yellow emitters were successfully produced from the integrated 60-μm-wide microchannels as well as the 1000-μm-wide microchannels. CIE coordinates of the greenish-blue, yellow, and white-light emission under the applied voltage of 100 V are shown in Fig. 5(c). The obtained CIE coordinates of the 1000-μm-wide electro-microfluidic devices with PLQ and TBRb-doped PLQ at 100 V were (0.16, 0.26) and (0.49, 0.47), respectively. The microfluidic WOLED through the simultaneous greenish-blue and yellow emissions showed the CIE coordinates of (0.40, 0.42) at 100 V, which is within the white region and nearly corresponds to warm-white27. White balance of our microfluidic WOLED can be simply tuned by varying microchannel-width ratios for greenish-blue and yellow liquid emitters (see Fig. S1). This color-tunable characteristic with microfluidic technologies is an innovative property.

Bottom Line: The fabricated electro-microfluidic device successfully exhibited white electroluminescence (EL) emission via simultaneous greenish-blue and yellow emissions under an applied voltage of 100 V.A white emission with Commission Internationale de l'Declairage (CIE) color coordinates of (0.40, 0.42) was also obtained; the emission corresponds to warm-white light.The proposed device has potential applications in subpixels of liquid-based microdisplays and for lighting.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Science and Engineering, Waseda University 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.

ABSTRACT
We demonstrated a novel microfluidic white organic light-emitting diode (microfluidic WOLED) based on integrated sub-100-μm-wide microchannels. Single-μm-thick SU-8-based microchannels, which were sandwiched between indium tin oxide (ITO) anode and cathode pairs, were fabricated by photolithography and heterogeneous bonding technologies. 1-Pyrenebutyric acid 2-ethylhexyl ester (PLQ) was used as a solvent-free greenish-blue liquid emitter, while 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb)-doped PLQ was applied as a yellow liquid emitter. In order to form the liquid white light-emitting layer, the greenish-blue and yellow liquid emitters were alternately injected into the integrated microchannels. The fabricated electro-microfluidic device successfully exhibited white electroluminescence (EL) emission via simultaneous greenish-blue and yellow emissions under an applied voltage of 100 V. A white emission with Commission Internationale de l'Declairage (CIE) color coordinates of (0.40, 0.42) was also obtained; the emission corresponds to warm-white light. The proposed device has potential applications in subpixels of liquid-based microdisplays and for lighting.

No MeSH data available.