Journal of the Society for Information Display最新文献

In this paper, we obtained the optimal structure of QLED top-emission spin-coating device. Meanwhile, we also have successfully developed quantum dots and ZnO ink materials with high stability. With the top-emission device structure and stable ink materials, we optimize the morphology of every film by controlling the drying process after ink-jet printing. The emission area of united devices prepared by using the optimized ink-jet printing process is equal to the designed area of pixels, with clear boundaries, uniform electroluminescent morphologies within a single sub-pixel, and no significant difference in luminescence between pixels. Finally, we assembled and fabricated a 55-in. 8K AMQLED display with a color gamut of 116% NTSC.

Pico-projection displays are the main developing direction for future projection displays, but the balance between the optical efficiency and the system size is still a big concern. This paper presents a pico-projector design based on micro-LED (μLED) light sources. Firstly, based on the analysis of the characteristics of μLED, a highly integrated microlens array is designed to improve the system efficiency by reshaping the spatial light distribution. In addition, the matching relationship between the aperture angle of projection lens and the divergence angle of μLED is studied, and on this basis, a set of four-piece spherical lens group is proposed to achieve compact size. Simulation results show that the μLED equipped with the microlens array can concentrate about 86% of the light energy within a dispersion angle of ±20°, thus increasing the light energy utilization by about 3.5 times and reducing the size of the pico-projector to 30.18 mm³. The designed pico-projector has high performance and compact size with great potential for future applications.

Due to the instability of perovskite quantum-dots (PQDs), their applications in optoelectronic devices, in reality, are limited. In this paper, Cs(Pb,Sb)Br₃ PQDs@glasses were successfully prepared by traditional melting quenching and heat treatment methods. The optical characterization shows that Cs(Pb_0.7Sb_0.3)Br₃ PQDs@glasses has an emission peak of 518 nm and a full width at half maximum of 20 nm, and the photoluminescence quantum yield (PLQY) is 58%. The electronic structure of Cs(Pb_0.875Sb_0.125)Br₃ has been studied by first principles. The stable range of chemical potential of each element in CsPbBr₃ is calculated by first principles. It is proved that CsPbBr₃ is an excellent PQDs luminescent material. The thermal analysis and temperature-dependent photoluminescence spectra prove the stability of the PQDs@glass within 200°. The thermal distribution of the sample under laser irradiation is measured by a finite element method. In addition, Cs(Pb,Sb)Br₃ PQDs@glasses are combined with AlN-(Ca,Eu)AlSiN₃ ceramic phosphors to prepare phosphor wheels, which shows that these materials have potential application prospects in the field of display.

Pancake lens structure offers a promising solution to compact formfactor for near-eye displays. However, utilizing a half mirror to triple the optical path length causes a dramatic optical loss. The theoretical maximum optical efficiency is only 25%. To balance the tradeoff between compact formfactor and optical efficiency, here we propose a new folded optical structure with a doubled efficiency and doubled optical path length, using two polarization-selective cholesteric liquid crystal reflectors. Simulation results agree with the experiment reasonably well. Two display configurations are established to evaluate the imaging performances of the proposed pancake lens structure.

Reflective polarization volume gratings (PVGs) can be used as input and output couplers in a diffractive waveguide-based augmented reality (AR). To improve the stability and wearing comfort, a thin and lightweight full-color waveguide display is needed. In this paper, we propose a single full-color waveguide AR display based on PVGs. By analyzing the optical system, we derived the field of view limit by optimizing a three-layer PVG as an in-coupler. Pairing with a single-layer, thin PVG as an out-coupler, we can achieve a relatively uniform exit pupil of 8 mm at horizontal pupil expansion direction.

We have developed novel cholesteric liquid crystal (Ch-LC) films creating angle insensitive reflective colors. The wavy alignment formed by rapid change of the helical twisting power (HTP) enables the suppression of color shift with different incident angles of light. These films open the door to create various decorative films for innovative applications.

In this work, we investigated the potential for phosphorescent emitters to achieve the BT.2020 color standard in displays, where the CIE coordinates for red and green are (0.709, 0.292) and (0.170, 0.797), respectively. Optical simulations were performed for both green and red top emission organic light emitting devices (OLEDs). For the green emitter, it is possible to reach (0.170, 0.785) using a spectrum with a peak wavelength (λ_max) at 526 nm and a full width at half maximum (FWHM) less than 30 nm. For the red emitter, in order to achieve (0.708, 0.292) while maintaining a high current efficiency (CE), it is important to decrease the FWHM instead of red-shifting the spectrum. Following the guidance of these simulation results, we designed and synthesized novel deep green (DGD) and deep red phosphorescent (DRD-II) emitters. The photoluminescent (PL) spectrum of DGD shows an FWHM of 30 nm and a λ_max of 523 nm. A top-emission green OLED built using DGD reached a CE of 171 cd/A at an operating voltage of 3.3 V and a lifetime of 95% of initial brightness (LT₉₅) > 1300 h at 10 mA/cm² with a CIE (x, y) = (0.170, 0.777). This is, to our knowledge, the best device performance ever reported for a green phosphorescent OLED at this CIE y. The PL spectrum of DRD-II has a λ_max of 630 nm with an FWHM of 30 nm. A top-emission red OLED built with DRD-II achieved a CE of 59 cd/A, an operating voltage of 3.2 V and an LT₉₅ over 20,000 h at a drive current of 10 mA/cm² with a CIE (x, y) = (0.708, 0.292). We also studied the angular dependence of the above devices and found they were comparable to devices with commercial emitters for the Digital Cinema Initiative P3 (DCI-P3) standard that had a wider FWHM. Combining these green and red emitters with a commercial blue OLED at (0.131, 0.046), we are able to cover 97% of the BT.2020 color gamut. The results using DGD and DRD-II suggest that they have great potential to satisfy BT.2020 in an organic phosphorescent system.

In this work, real-time ultraviolet photodetectors are realized through metal–semiconductor–metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R, a low response time t_RES, and a good noise equivalent power value NEP.