Spectrally narrowed edge emission from organic light-emitting diodes

Tian, Yun; Gan, Zhengqing; Zhou, Ziwu; Lynch, David W.; Shinar, J.; Kang, Ji-Hun; Park, Q-Han

doi:10.1063/1.2778358

Cited by 18 publications

(6 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other claims of electrically-driven stimulated emission have been reported during the XXI th century: Yokoyama et al [126] observed a spectral narrowing of the edge emission of an OLED as well as an intriguing superlinear dependence of the emission with the electrode length, which was attributed to the presence of stimulated emission. Tian et al [24] observed the same features but suggested that a misalignment of the collecting optics could be the reason for the observed superlinear dependence instead of gain. In both cases, the spectral narrowing can be well accounted by a resonant leaky mode at the cut-off frequency [126].…”

Section: Prospects For Electrical Pumpingmentioning

confidence: 70%

“…First of all, the quest of the "organic laser diode" remains the top keyword that drives the scientific community. Many insights contributed to a better understanding of the bottlenecks caused by the supplementary losses brought by electrical excitation; surprisingly though, some claims of apparent gain or lasing action [23] under electrical excitation have been published, but they were later attributed to artefacts [24] or mistaken identification of laser action [25]. These aspects will be reviewed in Section 4.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Recent advances in solid‐state organic lasers

Chénais

Forget

2011

Polymer International

346

280

View full text Add to dashboard Cite

Organic solid-state lasers are reviewed, with a special emphasis on works published during the last decade. Referring originally to dyes in solid-state polymeric matrices, organic lasers also include the rich family of organic semiconductors, paced by the rapid development of organic light emitting diodes. Organic lasers are broadly tunable coherent sources are potentially compact, convenient and manufactured at low-costs. In this review, we describe the basic photophysics of the materials used as gain media in organic lasers with a specific look at the distinctive feature of dyes and semiconductors. We also outline the laser architectures used in state-of-the-art organic lasers and the performances of these devices with regard to output power, lifetime, and beam quality. A survey of the recent trends in the field is given, highlighting the latest developments in terms of wavelength coverage, wavelength agility, efficiency and compactness, or towards integrated low-cost sources, with a special focus on the great challenges remaining for achieving direct electrical pumping. Finally, we discuss the very recent demonstration of new kinds of organic lasers based on polaritons or surface plasmons, which open new and very promising routes in the field of organic nanophotonics.

show abstract

Section: Prospects For Electrical Pumpingmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Recent advances in solid‐state organic lasers

Chénais

Forget

2011

Polymer International

346

280

View full text Add to dashboard Cite

show abstract

“…Such measurements are typically conducted to provide evidence for optical gain, and consequent ASE in inorganic semiconductors and optically pumped organic films. 9,10 To our knowledge, our preceding paper 8 and this paper describe the first detailed VSL measurements in electrically pumped organic devices. When conducting the VSL measurements, the length of the Al cathode was shortened for each step, by either 1 or 0.5 mm.…”

Section: Methodsmentioning

confidence: 99%

“…This paper describes striking spectrally narrowed edge emission ͑SNEE͒ from small molecular OLEDs ͑SMOLEDs͒ 7,8 and measurements on these devices with variable stripe length ͑VSL͒, 9,10 which exhibit an apparent weak optical gain. These are two key features of amplified spontaneous emission ͑ASE͒, i.e., mirrorless lasing.…”

Section: Spectrally Narrowed Edge Emission From Leaky Waveguide Modesmentioning

confidence: 99%

Spectrally narrowed edge emission from leaky waveguide modes in organic light-emitting diodes

Gan

Tian

Lynch

et al. 2009

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

A dramatic spectral line narrowing of the edge emission at room temperature from tris(quinolinolate) Al (Alq3), N,N′-diphenyl-N,N′-bis(1-naphthylphenyl)-1,1′-biphenyl-4,4′-diamine (NPD), 4,4′-bis(2,2′-diphenyl-vinyl)-,1′-biphenyl (DPVBi), and some guest-host small molecular organic light-emitting diodes(OLEDs), fabricated on indium tin oxide (ITO)-coated glass, is described. In all but the DPVBi OLEDs, the narrowed emission band emerges above a threshold thickness of the emitting layer, and narrows down to a full width at half maximum of only 5-10 nm. The results demonstrate that this narrowed emission is due to irregular waveguide modes that leak from the ITO to the glass substrate at a grazing angle. While measurements of variable stripe length l devices exhibit an apparent weak optical gain 0≤g≤1.86 cm−1, there is no observable threshold current or bias associated with this spectral narrowing. In addition, in the phosphorescent guest-host OLEDs, there is no decrease in the emission decay time of the narrowed edge emission relative to the broad surface emission. It is suspected that the apparent weak optical gain is due to misalignment of the axis of the waveguided mode and the axis of the collection lens of the probe. However, it is not clear if such a misalignment can account for all the effects of the observed evolution of the edgeemission spectra with l. KeywordsAmes Laboratory, Organic light emitting diodes, Glass waveguides, Spontaneous emission, Cathodes, Emission spectra A dramatic spectral line narrowing of the edge emission at room temperature from tris͑quinolinolate͒ Al ͑Alq 3 ͒, N , , 4Ј-diamine ͑NPD͒, 4,4Ј-bis͑2,2Ј-diphenyl-vinyl͒-,1Ј-biphenyl ͑DPVBi͒, and some guest-host small molecular organic light-emitting diodes ͑OLEDs͒, fabricated on indium tin oxide ͑ITO͒-coated glass, is described. In all but the DPVBi OLEDs, the narrowed emission band emerges above a threshold thickness of the emitting layer, and narrows down to a full width at half maximum of only 5-10 nm. The results demonstrate that this narrowed emission is due to irregular waveguide modes that leak from the ITO to the glass substrate at a grazing angle. While measurements of variable stripe length l devices exhibit an apparent weak optical gain 0 Յ g Յ 1.86 cm −1 , there is no observable threshold current or bias associated with this spectral narrowing. In addition, in the phosphorescent guest-host OLEDs, there is no decrease in the emission decay time of the narrowed edge emission relative to the broad surface emission. It is suspected that the apparent weak optical gain is due to misalignment of the axis of the waveguided mode and the axis of the collection lens of the probe. However, it is not clear if such a misalignment can account for all the effects of the observed evolution of the edge-emission spectra with l.

show abstract

“…We therefore attribute this to the existence of leaky waves with propagation angles close to the critical angle for TIR and travelling in a direction nearly parallel to the layer interface. [14,15] The fluorescence inside the film effectively couples to these leaky modes leading to the much wider edge emission.…”

mentioning

confidence: 99%