A multi-zoned white organic light-emitting diode with high CRI and low color temperature

Abstract

White organic light emitting diodes (WOLEDs) is becoming a new platform technology for a range of applications such as flat-panel displays, solid-state lightings etc., and are under intensive research. For general solid-state illumination applications, a WOLED’s color rendering index (CRI) and correlated color temperature (CCT) are two crucial parameters. This paper reports that WOLED device structures can be constructed using four stacked emission layers which independently emit lights at blue, green, yellow and red color respectively. The intensity of each emission layer is then engineered by funneling excitons to the targeted emission layer to achieve an ultrahigh 92 CRI at 5000 cd/m2, and to reduce CCT to below 2500 K.

External Quantum Efficiency Exceeding 24% with CIEy Value of 0.08 using a Novel Carbene‐Based Iridium Complex in Deep‐Blue Phosphorescent Organic Light‐Emitting Diodes

“…Previous studies have shown that the threshold voltage and carrier density changes in HODs and EODs are due to charge trapping by dopants and the carrier transport abilities of hosts. [41][42][43][44] Recently, Ryu et al [44] demonstrated carrier balance in EMLs at different dopant concentrations, which showed concentration quenching was induced by electron and hole imbalance in the EML. The present study demonstrates that carrier balance in the EML was greatly affected by (1) HOMO and LUMO energy levels of host and dopant in the EML, (2) the carrier transport properties of host and dopant materials, and (3) dopant concentrations in EMLs.…”

Cyan phosphors for full-visible-spectrum lighting: shining new light on high-CRI white pc-LEDs

“…Typically, a light source with a CRI > 70 is acceptable for outdoor lighting, whereas a CRI > 80 is required for indoor lighting. However, light sources with a high CRI > 90 are desirable in colorcritical applications such as photography, cinematography, museum and art gallery, jewelry shops, surgery, as well as printing and painting businesses [5,6]. Generally speaking, light sources possessing a wider emission spectrum are more likely to offer higher CRI values.…”

Exciplex-Forming Systems of Physically Mixed and Covalently Bonded Benzoyl-1H-1,2,3-Triazole and Carbazole Moieties for Solution-Processed White OLEDs

“… 19 − 22 The color rendering index (CRI) scale ranges from 0 to 100 and describes the ability of the light source to exhibit colors realistically in comparison with a standard incandescent lamp. 23 , 24 It is also a known fact that to realize high CRI, a WOLED should have an as broad as possible emission spectrum. 25 , 26 Ultra-high CRI is important for lighting applications in museums, art galleries, and other commercial places.…”