EL ‘04 • 1 Demonstration of Fluorescent RGB Electrowetting Devices for Light Wave Coupling Displays J. Heikenfeld, and A. J. Steckl Extreme Photonix LLC, Cincinnati Ohio, USA and Nanoelectronics Laboratory, Dept. of Electrical Engineering, University of Cincinnati, Cincinnati, Ohio, USA Abstract We present an emissive light valve approach which possesses ~10-40X higher theoretical luminous efficiency than transmissive LCD light valves. This innovative light valve approach has been applied to a novel fluorescent display technology utilizing light wave coupling. Switchable pixelation has been achieved using an innovative electrowetting modulation method. Maximum luminance values of 950, 5530, and 530 cd/m 2 have been achieved for red, green, and blue emission, respectively. Switching speeds of ~100 ms and ~10 ms for ON/OFF switching have been demonstrated, respectively. Introduction A long-standing competition between transmissive and emissive displays continues to present day. Established and novel emissive displays have experienced difficulty in keeping pace with rapid advancements in transmissive LCD displays[1]. LCD researchers have made impressive breakthroughs in order to overcome many of the limitations thought to be inherent to any display based on liquid crystals. LCDs can be classified as a TRANSMISSIVE light valve approach. By utilizing the light valve approach pixel luminance for LCDs is determined by the panel backlight. However, even at maximum transmission, color LCDs typically are only able to transmit 5-10% of light from the back-light module. Furthermore, for LCD pixels in the OFF state, light is absorbed and wasted, instead of recycling the light for use at pixels in the ON state. We present the demonstration of an EMISSIVE light valve technology for displays. This novel approach possesses ~10-40X higher theoretical luminous efficiency than LCD light valves. This new light valve has been applied to a unique display panel and lighting concept we have developed: Light Wave Coupling (LWC) [2]. As shown in Fig.1, the LWC display device we report here innovatively combines three critical components: (1) an UV light storage plate edge pumped by an ultra-efficient violet light source; (2) a light wave coupling region defined by apertures in an optical cladding on the UV light storage plate; (3) red, green, and blue fluorescent oils which are switchably coupled to the UV light storage plate through electrowetting. Building an LWC Light Valve The UV light sources chosen for edge-pumping are preferably closer to the violet (~400 nm) portion of the electromagnetic spectrum. Use of violet light instead of shorter wavelength UV (<350 nm) light sources reduces optical absorption losses in the display optics and acts a ‘soft’ excitation source which does not photo-degrade the organic fluorescent oils. Violet light sources include custom developed cold-cathode- fluorescent lamps or arrays of violet InGaN LEDs. The light storage plate is chosen simply from flexible (polymer) or rigid (glass) substrates which have a refractive index of ~1.5 and are UV Fig. 1 Device structure and operation for electrowetting-based switching for LWC displays.