Akiyoshi Mikami

High-Efficiency Color and White Organic Light-Emitting Devices Prepared on Flexible Plastic Substrates

Blue, green and white organic light-emitting devices doped with fluorescent dyes have been successfully fabricated on high-refractive-index plastic substrates and characterized in terms of their electrical and optical properties. The devices consist of a wide-band-gap polymer emissive layer stacked with several small-molecule layers and were designed considering carrier balance, carrier confinement, dye-guest doping and optical characteristics. It was demonstrated that dye-doped polymer devices are effective for the improvement of color and emission efficiency. We demonstrated deep-blue-, bright-green- and pure-white light-emitting devices having external quantum efficiencies and color coordinates (x,y) of 6.0% (0.15,0.07), 5.5% (0.20,0.60) and 4.0% (0.33,0.33), respectively.

60.4L: Late‐News Paper: High Efficiency 200‐lm/W Green Light Emitting Organic Devices Prepared on High‐Index of Refraction Substrate

The total flux of the emitted light has been successfully enhanced by employing high refractive index (n=2.0) glass substrate coated with a light extraction layer. The normal CBP:Ir(ppy)3 based small molecule multilayer device exhibits a maximum external quantum efficiency of 56.9% and a power efficiency of 210-lm/W with a threshold voltage of 2.7V. Optical mode analysis by original computer software identified the importance of the control of refractive index of substrate for total improvement of out-coupling efficiency.

17.2: High Efficiency Ultraviolet Light Emitting Organic Devices and Its Application to White Light Source

A high efficiency UV-OLED was developed and applied to a white light source by using red, green and blue color conversion materials. UV-OLED showed high external quantum efficiency of 3.1 % with a peak wavelength at 380nm. “White by UV” showed 5,000cd/m2 in luminance and stable white color (x=0.33, y=0.31) against driving current and operation time.

35-3: High Efficiency Phosphorescent Organic Light-Emitting Devices Coupled with Lateral Color-Conversion Layer

A high efficiency phosphorescent light-emitting organic device has been developed based on a Side-Coupling-Color-Conversion-Method, in which the color-conversion layer was excited by the propagating light laterally transferred from the organic light emitting layer. The device showed an external quantum efficiency (EQE) of 24.2% by using a phosphorescent excitation light with 19.4% of EQE.

11.1: High-Efficiency Color and White-Light-Emitting Polymer Devices with High-Index-of-Refraction Flexible Plastic Substrate

In this paper, we describe that fluorescent guest doped polymer light-emitting devices have been successfully fabricated on high index of refraction plastic substrate and characterized in terms of electrical and optical viewpoints. Deep blue, bright green and pure white OLEDs showed external quantum efficiencies and color coordinates (x,y) of 5.1% (0.15,0.09), 5.5% (0.20,0.60) and 4.0% (0.33,0.33), respectively.

Optical design and analysis of high efficiency organic green light emitting devices with light extraction structure

Light extraction efficiency has been enhanced by using weak micro-cavity structure and high refractive index substrate coupled with micro-lens array. Phosphorescent green light emitting device designed by wave optics showed external quantum efficiencies more than 50% and power efficiencies of 200-lm/W.