Colour Electronic Information Displays (EIDs) typically consist of pixels that are made up of red, green and blue (RGB) subpixels. A recent technology, Organic Light Emitting Diode (OLED), offers the potential to create a superior EID. OLED is already suitable for use in small displays and microdisplays for personal electronics products. OLED microdisplays, in particular, exhibit lower power consumption than equivalent direct-view panels thus enabling microdisplay-based personal display systems such as electronic viewfinders and video glasses to exhibit the longest possible battery life. In many EIDs, the light source is white and colour filters are used, at the expense of much absorbed light, to create the RGB light in the subpixels. Hence, the concept has recently emerged of adding a white (W) subpixel to form an RGBW pixel. The advantages can include lower power, higher luminance, and in the case of emissive displays, longer lifetime. One key to realizing the improved performance of RGBW EIDs is a suitable method of data conversion from standard RGB input signal formats to RGBW output signal formats. An OLED microdisplay built on Complementary Metal–Oxide–Semiconductor (CMOS) active matrix back-plane exhibits low power consumption. This device architecture also gives the OLED microdisplay the potential to realize the concept of low-power Display System on a Chip (DSoC). In realizing the performance potential of DSoC on an RGBW OLED microdisplay, there is a trade-off between system resources used to perform the data conversion and the image quality achieved. A compact and efficient method of RGB-to-RGBW data conversion is introduced to fit the requirement of “minimum system resources with indistinguishable visual side-effect” that is appropriate for an OLED microdisplay. In this context, the terms “Compact” and “Efficient” mean that the data conversion functionality (i) is capable of insertion into the signal path, (ii) is capable of integration on the OLED microdisplay back-plane, i.e., is small and (iii) consumes minimal power. The image quality produced by the algorithm is first simulated on a software platform, followed by an optical analysis of the output of the algorithm implemented on a real time hardware platform. The optical analysis shows good preservation of colour fidelity in the image on the microdisplay so that the proposed RGB-to-RGBW data conversion algorithm delivers sufficiently high image quality whilst remaining compact and efficient to meet the development requirements of the RGBW OLED microdisplay with DSoC approach.

The immersive virtual reality (VR) and the optical see-through augmented reality (AR) are expected to revolutionize human lives in work, education, entertainment, healthcare, spatial computing, and digital twins, just to name a few. Next-generation VR/AR devices should exhibit a wide field-of-view (FoV), crisp image without screen-door effect, high dynamic range, compact form factor and lightweight, and low power consumption. Such demanding requirements pose a significant challenge to traditional direct-view display panels. To address these technical challenges, novel approaches need to be proposed. This dissertation is devoted to developing next-generation high-performance display light engines toward high resolution density, high optical efficiency, wide color gamut, and small form factor. These emerging solutions will fuel the growth and accelerate the widespread applications of VR/AR devices. In Chapter 2, we propose practical measurement methods to characterize the halo artifacts of miniature light-emitting diode (mini-LED) backlit liquid crystal displays (LCDs). After measuring and characterizing a high dynamic range (HDR) light engine, we propose and develop field sequential color (FSC) LCDs for high-end virtual reality (VR) devices in Chapter 3. Such an FSC LCD can triple the resolution density and optical efficiency via eliminating color filters. To further mitigate the color breakup (CBU), we also propose to combine mini-LEDs with FSC LCDs to enable progressive emission and achieve a higher frame rate (~ 600 Hz). To quantitatively compare the CBUs corresponding to simultaneous emission, progressive emission, and stencil algorithm, we adopt the CIEDE2000 color difference as a metric. Quantitative simulation results of the CBU indicate that a 600-Hz subframe rate can help mitigate the CBU dramatically. Micro organic light-emitting diode (micro-OLED) exhibiting high-resolution density and high contrast ratio is another type of display for high-end VR devices. More specifically, white micro-OLED is currently employed because it helps ease the manufacturing difficulty. In Chapter 4, we optimize the layer thicknesses to achieve a maximum efficiency while keeping a decent color gamut. We also push the limit of color gamut toward ~ 95% Rec. 2020. Lastly, liquid-crystal-on-silicon (LCoS) offers great potential for achieving high-efficiency and high-resolution waveguide-based AR displays. In Chapter 5, several strategies are proposed and developed to improve the performance of LCoS microdisplays and enable a small pixel size. In Chapter 6, we briefly summarize our major accomplishments.

Ce travail porte sur la réalisation d'un micro-écran OLED haute luminance sur silicium. L'efficacité limitée des structures WOLED associées à des filtres colorés est un frein au développement de cette technologie pour des applications dans des dispositifs de type « see-through ». Nous proposons une approche tirant parti de l'effet de microcavité optique présent dans les écrans OLED à émission vers le haut pour générer des couleurs sans filtres. Les modulations de cavité à l'échelle du sous-pixel étant assurées par l'insertion d'oxyde transparent conducteur entre l'anode et l'OLED.L'étude offre selon un raisonnement cohérent de suivre les différentes phases de la réalisation d'un démonstrateur de ce type. Seront abordées dans la première partie les étapes technologiques de structuration de l'oxyde à l'échelle d'un sous-pixel de 16µm². Nous traiterons ensuite du développement d'un empilement OLED tandem utilisant des émetteurs fluorescent et phosphorescents. Une approche par simulation optique sera utilisée pour l'optimisation de cette architecture à un fonctionnement sur microcavité. Puis la discussion autour de la mise en commun des blocs technologiques précédents permettra d'aborder des écueils spécifiques au micro-écran OLED et de proposer des pistes de résolution. / This study focuses on the realization of a high brightness OLED micro-écran on silicon. The limited efficiency of White-OLED combined with color filters prevents the use of this technology in “see-through” applications. We propose a novel approach getting benefits from the optical micro-cavity effect in Top-Emitting OLED to generate colors without using color filters. Cavity modulations at a sub-pixel scale are realized by using a Transparent Conducting Oxide between the anode and the OLED.Following a step-by-step reasoning the work offers to follow all the phases of the realization of a prototype using this principle. In the first part, the technological steps of the processing of oxide cavities with a surface of 16µm² will be discussed. Then we will work on the development of a tandem OLED structure using both fluorescent and phosphorescent emitters optimized for micro-cavities. To this end optical simulation will be used. The two technological blocs will finally be put together to enlighten some issues specific for micro-écran technology and to give some clues to solve them.

La travail présente traite du développement de diodes organiques électroluminescentes(OLEDs) a haute luminance pour des applications dans des micro écrans. Ces dispositifs sontbases sur des substrats silicium utilisent la technologie CMOS. Le présent ouvrage met en avantles efforts développe afin de réduire la dérive en tension et ma décroissance lumineuse enopération des dispositifs lumineux.Dans la première partie de l’étude, des OLEDs vertes haute luminance fonctionnant àbasse tension sont développes. L’empilement organique a émission vers le haut comprenant unémetteur fluorescent vert entre des couches de blocage de charges et des couches de transportdopées. Les effets de différentes structures de dispositifs, des configurations de l’empilement etdes matériaux organiques sur les performances initiales et en opération sont reportés ici.Dans la deuxième partie de l’étude, le développement de dispositifs OLED hybrides pourmicro écrans couleurs est présenté. Les structures hybrides comprennent une couche detransport de trous photosensible et traitable par solution (X-HTL) et d’une OLED blancheréalisée par évaporation sous vide. Cette méthode permet la génération de couleur directe, ellepermet ainsi d’obtenir de très bonnes efficacités et un contrôle aisé de la couleur émise parsimple modification de l’épaisseur de X-HTL. / The present work reports the development of high luminance organic light emitting diodes(OLEDs) device stacks for microdisplay applications. The devices are based on siliconcomplementary metal-oxide semiconductor (CMOS) backplane. In the present treatise effortsare particularly focused on reducing the luminance decay and the voltage drift during deviceoperation.In the first part of this study, high brightness and low operating voltage green OLEDs arereported. The top emitting device stack comprises of fluorescent green emitter accompanied bycharge blocking layers and doped charge transport layers. The effect of different devicestructures, configurations and organic materials on the initial and lifetime performance of thedevice is presented.In the second part of the study, device development of hybrid OLED stacks for high luminancefull color microdisplays is reported. The hybrid devices comprise of a solution processed andphotocrosslinkable hole transport layer (X-HTL) and an evaporated white OLED stack. Thismethod allows direct primary color generation with relatively high efficiency and offers ease ofcolor tunability by controlling the thickness of the X-HTL.