Jin-Sheng Lin

Suppression of efficiency roll off in blue phosphorescent organic light-emitting devices using double emission layers with additional carrier-transporting material

By employing double emission layers (DELs) into blue phosphorescent organic light-emitting device (PHOLED), the device shows improved current efficiency by a factor of 1.8 as compared with that of device using single emission layer. Furthermore, by doping additional carrier-transporting material into DELs, the device shows only a slight efficiency roll off of 24% from low (1 mA/cm2 and 400 cd/m2) to high current density (40 mA/cm2 and 10 000 cd/m2). The dramatic improvement in device performances can be attributed to the formation of a broader carrier recombination zone and the elimination of carrier accumulation at the interface. A blue PHOLED with a current efficiency of 29.5 cd/A, a power efficiency of 21 lm/W, and a low driving voltage of 4.4 V with a Commission Internationale deL’Eclairage (CIEx,y) of (0.16, 0.35) at a practical brightness of 1000 cd/m2 can be achieved.

Low-voltage, high-efficiency blue phosphorescent organic light-emitting devices

Low-voltage, high-efficiency blue phosphorescent organic light-emitting devices based on a composite emitter, including a wide-band-gap host, a carrier-transporting material, and an organometallic iridium dopant, have been demonstrated. The devices exhibit an external quantum efficiency of 12%, a power efficiency of 17lm∕W and a low voltage of 4.8V at a practical brightness of 1000cd∕m2 with a CIEx,y of (0.16, 0.35), which was twofold higher than that of using the typical emitter composed of host and dopant only. The dramatic enhancement in performance can be attributed to the transport of carriers into the wide-band-gap host, which can be promoted through doping a carrier-transporting material in emitter for increasing carrier recombination.

P-221L: Late-News Poster: New Blue Phosphorescent Host for High-efficiency White OLED

A new blue phosphorescent host with an electron transporting dibenzothiophene molecular skeleton connected to hole transporting carbazolyl moiety has been developed. Using this material, an all-phosphorescent white OLED with a high power efficiency of 60 lm/W, a low driving voltage of 3.6V and a color-rendering index of 75 at practical brightness of 1000 cd/m2 can be achieved.

Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement

In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m2, which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect result...

The application of high efficient yellow phosphorescent material to white OLEDs

A new type of thiopyridinyl-based iridium molecule (POT) was used as the yellow phosphorescent material in our research. On fabricating a yellow PHOLED by doping POT-02 with host as the emitter, the device achieved a high power efficiency of 66.0 lm/W and an external quantum efficiency of 23.2%. On the other hand, a white organic lightemitting diode (WOLED) with a high power efficiency has been demonstrated by dispersing a host-free, yellow phosphorescent material in-between double blue phosphorescent emitters. In this study, we introduce a simple process for generating yellow emission of a WOLED by using the B/Y/B EML configuration. The B/Y/B EML configuration can achieve a higher efficiency and a smaller color shift with various operational brightness values. Based on the concept of this device, the molecular engineering of the blue phosphorescent host material as well as the light-extraction film, a WOLED with a power efficiency of 103 lm/W and an external quantum efficiency of 38.2% at a practical brightness of 1000 cd/m2 with CIE coordinates (CIEx, y) of (0.36, 0.48) can be achieved.

Highly efficient organic light emitting diodes based on solution/evaporation hybrid process

The solution/evaporation hybrid processed organic light emitting devices composed of newly developed host material CzDBS, green PG-02 dopant, and orange PO-01-TB and PO-06 dopants are studied. Orange, green and two-peak white light emitting devices were fabricated by using spin coating of HIL, HTL and emission layers followed by thermal evaporation of ETL and cathode. The orange devices achieved efficacies of 26.9 cd/A and 14.6 lm/W at the brightness of 1538 nits. The green devices, on the other hand, achieved efficacies of 31.3 cd/A and 19.7 lm/W at the brightness of 1590 nits. The two-peak white devices, composed of blue FIrpic and orange PO-01-TB, achieved efficacies of 36.9 cd/A and 18.4 lm/W at the brightness of 1150 nits.

High-efficiency orange-red organic electrophosphorescent devices with excellent operational stability

A novel orange-red phosphorescent iridium complex PR-24 has been successfully synthesized and characterized. By using this material, we demonstrated the high-efficiency OLED devices. The best efficiency was achieved for a device using PR-24 as the dopant, exhibiting 25.8 cd/A current efficiency, 20.0 lm/W power efficiency and 15.9% EQE at 1000 cd/m2 . Moreover, when using the optimized co-host configuration, PR-24 shows a remarkable lifetime T50 of 211,000 h for an initial luminance of 1000 nits .

Recent progress on solution processable small molecules for organic light-emitting diodes in ITRI

A series of novel thieno[3,2-c]pyridine-based RGBY phosphorescent Ir complexes have been synthesized and characterized. Solution-processable double-layered OLEDs fabricated with theses materials as the light-emitting layer exhibit high efficiencies. The monochromatic large-area of 40 x 83 mm2 Yellow and Green OLEDs have also been demonstrated.

P‐154: High Efficiency White‐Phosphorescent OLED with Host‐Free Yellow Emitter

A white PHOLED with high power efficiency of 55 lm/W has been demonstrated by using a host-free yellow phosphorescent emitter sandwiched by double blue phosphorescent emitters. The white PHOLED with host-free yellow phosphorescent emitter achieved a comparable device performance to that of using complicated host-guest doped system. Based on this device concept as well as the molecular engineering of blue host material, highly efficient white PHOLED can be achieved.

P-151: Low-Voltage, High-Efficiency Blue Phosphorescent OLED Using Double Emission Layers

Employing double emission layers (DELs) into blue phosphorescent organic light-emitting devices (PHOLED), the device shows improved current efficiency by a factor of 1.8 compared to that of device using single emission layer (SEL). Furthermore, by doping additional carrier-transporting material into DELs, the device shows a slight efficiency roll-off of 24% from low (1 mA/cm2 and 400 cd/m2) to high current density (40 mA/cm2 and 10000 cd/m2). The dramatic improvement in device performances can be attributed to the formation of a broader carrier recombination zone and the elimination of carrier accumulation at interface. A blue PHOLED with a current efficiency of 29.5 cd/A, a power efficiency of 21 lm/W and a low driving voltage of 4.4 V with a CIEx,y of (0.16, 0.35) at a practical brightness of 1000 cd/m2 can be achieved.