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The subpixel size of high-resolution organic light-emitting diode (OLED) microdisplays measures a few micrometers. To achieve a full-color microdisplay, the current preference is to use photolithography technology on a white OLED instead of using a fine metal mask for patterning. The application of photolithography techniques allows for the creation of microcavity structures or color filters (CFs) to enhance color purity in each emitted color. This paper focuses on investigating specialized OLED device structures for high-resolution microdisplays. The characteristics of each structure, including efficiency and color gamut, are thoroughly discussed. The structure, combining microcavity and CF, achieves the widest color gamut, while microcavity structures show higher efficiency compared to CF-only structures. Tandem structures are also considered for improved efficiency and stability. [ABSTRACT FROM AUTHOR]

White light is of great technical interest in many photonic applications. In this work, colloidal solutions containing mutually immiscible green perovskite nanocrystals and red InP quantum dots are developed as color‐conversion (CC) materials for generating white light. By combining the green/red CC materials and a blue top‐emission organic light‐emitting diode as an excitation source, it is possible to generate white light with a range of color temperatures (CTs). The technical approach can be extended to a wide variety of photonic applications where controllable CT is desirable. [ABSTRACT FROM AUTHOR]

Organic light-emitting diode (OLED) microdisplays have received great attention owing to their excellent performance for augmented reality/virtual reality devices applications. However, high pixel density of OLED microdisplay causes electrical crosstalk, resulting in color distortion. This study investigated the current crosstalk ratio and changes in the color gamut caused by electrical crosstalk between sub-pixels in high-resolution full-color OLED microdisplays. A pixel structure of 3147 pixels per inch (PPI) with four sub-pixels and a single-stack white OLED with red, green, and blue color filters were used for the electrical crosstalk simulation. The results showed that the sheet resistance of the top and bottom electrodes of OLEDs rarely affected the electrical crosstalk. However, the current crosstalk ratio increased dramatically and the color gamut decreased as the sheet resistance of the common organic layer decreased. Furthermore, the color gamut of the OLED microdisplay decreased as the pixel density of the panel increased from 200 to 5000 PPI. Additionally, we fabricated a sub-pixel circuit to measure the electrical crosstalk current using a 3147 PPI scale multi-finger-type pixel structure and compared it with the simulation result. [ABSTRACT FROM AUTHOR]

In this paper, we developed high color gamut OLED microdisplay. To minimize the crosstalk, a single stack white OLED structure with RGB main peaks was adopted, and RGB color filters were directly patterned on the OLED. In addition, we designed the optical crosstalk prediction model, which could predict the light loss according to the thickness of the passivation layer. As a result, we achieved high color gamut of 125.0% at sRGB, which demonstrated the high color gamut OLED microdisplay. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) materials have emerged as an efficient emitter for achieving high efficiency of blue organic light emitting diodes (OLEDs). However, it is challenging to satisfy both high device efficiency and long operational lifetime together. Here, highly efficient and electrochemically stable blue TADF emitter, 5‐(5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracen‐7‐yl)‐10,15‐diphenyl‐10,15‐dihydro‐5H‐diindolo[3,2‐a:3′,2′‐c]carbazole (DBA‐DI) is designed and synthesized for high efficiency and long lifetime OLED. This emitter exhibits high photoluminescence quantum yield of 95.3%, small single‐triplet energy gap of 0.03 eV, short delayed exciton lifetime of 1.25 µs, and high bond dissociation energy (BDE). Also, phosphine oxide free high triplet energy host systems (single and mixed) and exciton blocking layer materials are analyzed using molecular and optical simulations to find an efficient host system with high BDE and suitable emission zone for high efficiency and stable OLEDs. The fabricated OLED with DBA‐DI and high triplet host exhibited a maximum external quantum efficiency (EQE) of 28.1% with blue CIE color coordinates of (0.16, 0.39) and long operational lifetime (LT50) of 329 h at the initial luminance of 1000 cd m−2. Furthermore, the mixed host‐based TADF device showed a slightly lower EQE of 26.4% and almost two times longer lifetime (LT50: 540 h) than the single host device. [ABSTRACT FROM AUTHOR]

[Display omitted] Organic-inorganic hybrid perovskite nanocrystals (PNCs), have superior optical properties that meet the high color standard of Rec. 2020, but poor environmental instability, which impedes their practical applications as light emitters in displays. Here, we report exceptionally stable PNC-incorporated color-converting material that, and that maintains its luminescence in various harsh environments. Our main approach is to use two kinds of siloxane hybrid materials: a passivating ligand on the surface of PNCs (M-PNC) and an encapsulating matrix (MP-SH); they induce significantly improved stability against moisture, oxygen, and light. The MP-SH film (M-PNC encapsulated by siloxane hybrid) was stable for 100 d in water, air at 85 °C with 85% relative humidity, various polar solvents, and continuous blue light irradiation without any additional protecting layer. Furthermore, we investigate reversible optical property healing characteristics that are induced by water-induced defect passivation mechanism, suppressing non-radiative recombination in perovskite crystals. We demonstrate a color-converted organic light-emitting diode that uses MP-SH and that has excellent optical characteristics and operating reliability. This approach to increasing the environmental stability of PNCs provides great potential toward commercialization of PNCs for use in stable color-converting layers of displays. [ABSTRACT FROM AUTHOR]

The optical and electrical properties of the top electrode are crucial for the structural design of top-emitting organic light-emitting diodes (OLEDs). A uniform metal layer, if obtainable, can be electrically excellent and optically well-tuned. In this study, Ag deposited with Mg at a concentration of 9:1 to form a metal thin film exhibits higher conductivity and higher transmittance than those of a neat Ag thin film within a thickness of 10 nm or less. In addition, the thin Mg:LiF (1:1) layer renders the Mg:Ag metal film more uniform and enhances its electron injection property. If a Mg:LiF/Mg:Ag thin film is applied to top-emitting white OLEDs, the driving voltage is lowered and the efficiency is improved. In addition, color shifts for viewing angles are reduced, and the emission characteristics are close to Lambertian. [Display omitted] • 10-nm-thick Mg:Ag (1:9) metal forms a more uniform film compared with neat Ag thin metal of the same thickness. • Thin Mg:LiF (1:1) layer improves the optical and electrical properties of the Mg:Ag thin film. • Top-emitting white OLED device with thin Mg:Ag shows higher efficiency and superior angular emission characteristics. [ABSTRACT FROM AUTHOR]

To implement primary colors in high-resolution organic light-emitting diode (OLED) microdisplays, color filters or cavity structures are applied to white OLEDs (WOLEDs). In terms of the high luminance and high color gamut required by microdisplays, two methods were experimentally compared in this study. In addition, a method for applying a color filter to WOLEDs with high-order cavity structures is proposed. The luminance of the proposed structure is lower than that of the cavity-only structure, but is similar to that obtained by applying a color filter to normal WOLEDs. Although previous methods do not satisfy the BT.2020 standard, the proposed structure achieves 90.8% of the BT.2020 standard. [Display omitted] • An OLED structure for high color gamut and high resolution microdisplay application is proposed. • Red, green, and blue are simultaneously strengthened in a high-order cavity structure. • Each color enhanced by a cavity effect is separated through a color filter to achieve high gamut. • The proposed structure achieves a color gamut of more than 90% based on BT.2020 standard. [ABSTRACT FROM AUTHOR]