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This paper reports on a metal mask‐less lithography (MML) process for RGB OLED displays. By integrating MML, tandem OLEDs, and a microlens array (MLA), ultra‐high resolution, high luminance, and robust reliability can be realized. The report also demonstrates an MLA using an S‐stripe MLA pattern. The prototype exhibits excellent properties, with a white light efficiency of 66.7 cd/A at 15,000 cd/m².

An OLED display with CAAC‐OS FETs monolithically stacked over SiFETs, capable of 32‐division control of resolution and frame rate, was fabricated. This enables display that conforms with foveal characteristics, thereby reducing the power consumed during operation. The display can be driven at 120 Hz, with reduced data transmission.

In this paper, we fabricate a 1.50‐inch, 3207‐ppi prototype OLED display with drivers capable of 32‐division driving, which is achieved by monolithically stacking CAAC‐OS FETs over SiFETs. This structure enables a narrow bezel and two‐dimensional driver arrangement, leading to independent driving of 32 pixel arrays with divided source and gate lines.

For high‐definition microdisplays with more than several thousands of pixels per inch (ppi), c‐axis‐aligned crystal indium‐gallium‐zinc oxide (CAAC‐IGZO) field‐effect transistors (FETs) are effective devices. Based on such a viewpoint, we have fabricated a 5291‐ppi organic light‐emitting diode (OLED) display using CAAC‐IGZO FETs with a channel length of 60 nm.

C‐axis‐aligned crystalline‐oxide semiconductor field‐effect transistor (CAAC‐OS FET) can be scaled down to a width and a length of 60 nm. We fabricated an organic light‐emitting diode (OLED) display with more than 5000 ppi, which is required in virtual reality (VR) display applications, using CAAC‐OS FETs as the backplane. C‐axis‐aligned crystalline‐oxide semiconductor field‐effect transistor (CAAC‐OS FET) can be scaled down to a width and a length of 60 nm. We fabricated an organic light‐emitting diode (OLED) display with more than 5000 ppi, which is required in virtual reality (VR) display applications, using CAAC‐OS FETs as the backplane.

C‐axis aligned crystalline oxide semiconductor field‐effect transistor (CAAC‐OS FET) can be scaled down to a width and length of 60 nm. We have fabricated an organic light‐emitting diode (OLED) display with more than 5000 ppi, which is required in virtual reality (VR) displays, by using CAAC‐OS FETs as the backplane.

This study aims to focus on a cover film with a considerably low Young's modulus to achieve robust and flexible displays. We fabricated a prototype flexible display with such a film on its surface and achieved a display with robustness and bendability, which can be used in various applications.

Hybrid displays produce high‐visibility images and consume less power in any environment by using OLED and reflective‐LC. We propose a novel process of a hybrid display. The hybrid display enables further reduction in power consumption of OLED in operation and produces less OLED‐LC operational interference, leading to reduced noise.

We have successfully fabricated an 8.34-inch 1058-ppi 8K x 4K flexible organic light-emitting diode (OLED) display. It exhibits the world’s highest resolution and pixel density among flexible OLED displays, offering excellent viewing-angle characteristics owing to the arrangement of subpixels in a zigzag pattern.

We prototyped a 2.78-in 1058-ppi OLED hybrid display. We employed an oxide semiconductor/oxide conductor (OS/OC) pixel (transparent pixel). In OS/OC pixels (transparent pixels), FETs, wirings, capacitors, and contact portions are transparent, achieving a high transmission area ratio of 66%.

We developed a high-sensitivity GaN photocathode that works in transmission mode. It has 40.9 % quantum efficiency at 310 nm wavelength. Conventional GaN photocathodes, both transmission mode and reflection mode, are made on a sapphire substrate using metal-organic vapor phase epitaxy (MOVPE). In reflection mode, a GaN photocathode has very high quantum efficiency (QE) of over 50 %. However, in transmission mode, the quantum efficiency of a GaN photocathode was about 25 % at 240 nm with this technique. Therefore, we developed a new GaN photocathode using a glass-bonding technique, where a GaN thin film was bonded to a glass face plate. We found out that constituting an Al- GaN layer on the light incidence side of the photocathode surface provided higher QE than a sole GaN layer type for transmission mode. We focused on the band bending of the photocathode, and analyzed QE for both transmission mode and reflection mode. We then verified the effectiveness of the AlGaN layer using the results from the analysis. The high-sensitivity UV photocathode will be used for flame detection, corona discharge observation, and other UV imaging.

We focused on the off-state current ($I_{\text{off}}$) of oxide semiconductor thin film transistors (TFT) (In--Ga--Zn-oxide TFTs), which is lower than that of amorphous silicon TFTs and successfully made a prototype of a 6.0-in. extended graphics array (XGA) reflective liquid crystal display (RLCD) panel integrally including a data selection demultiplexer and a scan driver and capable of displaying still images at 1/180 fps. When still images are displayed, the frame frequency can be set low. This means that the frequency of rewrites of image data is markedly reduced. This leads to the reduction in the power consumption of an LCD panel. Our panel can solve the problems of electronic paper displays: high drive voltage and difficulty of displaying moving images. Thus, our panel is suitable for electronic paper displays.