Outsmarting Waveguide Losses in Thin-Film Light-Emitting Diodes

Meerholz, Klaus; Müller, David C.

doi:10.1002/1616-3028(200108)11:4<251::aid-adfm251>3.0.co;2-y

Cited by 56 publications

(30 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To rationalize these results, we consider that the overall efficiency of an OLED is determined by the spin statistics (the probability to form singulet or triplet excitons), [20] the photoluminescence (PL) quantum yield (the probability that a singulet exciton emits light), waveguide losses, [21] and finally the recombination efficiency of charge carriers h rec . Except for the latter contribution, all others are constants for the devices studied here.…”

Section: Methodsmentioning

confidence: 99%

Continuously Variable Hole Injection in Organic Light Emitting Diodes

2002

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Continuously Variable Hole Injection in Organic Light Emitting Diodes

2002

View full text Add to dashboard Cite

“…In standard OLED structures only about 20% of the generated photons can leave the device in forward direction 39–43. Eighty percent of the generated light is trapped inside the organic layers or the substrate by total internal reflection.…”

Section: Microcavity Oled Simulationmentioning

confidence: 99%

Hybrid organic–inorganic materials for integrated optoelectronic devices

Wehlus

Körner

Nowy

et al. 2010

Physica Status Solidi (a)

View full text Add to dashboard Cite

A device containing a microcavity organic light‐emitting diode (OLED) and a magnetooptically active bismuth iron garnet (BIG) Bi3Fe5O12 waveguide combines a planar source for polarized light generation with the material exhibiting the highest known Faraday rotation at room temperature. To build such a device an optimization of garnets and OLEDs has to be done. For a good functionality of the device it is essential to maximize the light coupled from the OLED into the waveguide and to seperate s‐ and p‐polarized emitted light. To optimize the OLED emisson numerical simulations have been performed where material and thickness of the metal anode, as well as the thickness of the hole and the electron conducting layers were varied. The stacks with the best separation of s‐ and p‐polarized light and the highest coupling into the waveguide were determined, fabricated, and characterized regarding their electrical and optical properties. OLEDs have to be deposited on plane surfaces for exhibiting low leakage currents and thus being functional. In order to get plane and crack free BIG surfaces the garnet growth and surface formation were examined on various gadolinium gallium garnet (GGG) Gd3 Ga5 O12 and buffered non‐garnet substrates. GGG substrates with different cuts and lattice constants were characterized as well as yttrium iron garnet (YIG) Y3Fe5O12 and GGG buffered sapphire, silicon, and fused silica substrates. The garnet had to be structured to fabricate a planar waveguide. Therefore laser structuring and plasma etching techniques were utilized. The structured garnets were characterized regarding the wall roughness. The optical constants of YIG and BIG were determined from films deposited on silicon using ellipsometric measurements. The combination of microcavity OLED and garnet waveguide resulted in an integrated magnetooptical modulator whose functionality has been proven by applying an external magnetic field and measuring the rotation of the polarized light.

show abstract

“…In principle, we cannot obtain the external quantum efficiency greater than 20% even if c, g S/T , and q PL are nearly 100% because g out cannot reach over 20% in conventional OLEDs [13]. Thus, many research groups have focused on improvement of the out-coupling efficiency by using the additional films with special morphology such as micro-lens array or by embedding a certain nanostructure in between glass substrate and electrodes so that they change the direction of internally wave-guided beam to outside [14][15][16]. However, they were hardly applicable to the display application due to a pixel blur effect of such functional films.…”

Section: Introductionmentioning

confidence: 84%