Recent progress in the use of fluorescent and phosphorescent organic compounds for organic light-emitting diode lighting

Hyocheol, Jeong; Shin, Hoon−Kyu; Lee, Jae-Hyun; Kim, Beomjin; Park, Young-Il; Yook, Kyoung Soo; An, Byeong‐Kwan; Park, Jong‐Wook

doi:10.1117/1.jpe.5.057608

Cited by 51 publications

(23 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the pioneering work of Tang and Van Slyke, OLEDs have attracted tremendous attention from both industry and academia, and the research field has experienced a rapid progress. Until now, OLEDs have already been industrialized as lightening devices, portable displays for smart phones, and even large‐sized TV displays . They are regarded as the dominant lightening and flat‐panel displaying technology in the future .…”

Section: Introductionmentioning

confidence: 99%

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Wei

Voit

2018

Macromol. Rapid Commun.

122

100

View full text Add to dashboard Cite

several organic layers like hole injection layer, hole-and electron transport layer, and most importantly, the emissive layers (EML), inserted between the electrodes (Figure 1). Under external voltage, opposite charge carriers of holes and electrons are injected from anode and cathode and finally recombined to produce photons within the EML. [10][11][12] Emitters can largely determine not only the performance but also the processing methods of devices, and therefore they are the key material among all the components of the OLEDs. During the past three decades, the emitter materials have seen a rapid progress, from traditional fluorescent, phosphorescent, and triplet-triplet annihilation (TTA) materials into the era of thermally activated delayed fluorescent (TADF) materials, and from small molecules to polymers. [13] According to spin statistics, singlet and triplet excitons are formed within the EML at the ratio of 1:3, when OLED devices are working under electrical excitation; however, the organic emitters have different capabilities to utilize the exciton to induce photons which results in different efficiencies of OLED devices. The electricity-photon conversion efficiency of OLED can be evaluated by the quantum efficiency (QE), referring to the numeral ratio of photons to the injected electronhole pairs. [14,15] QE can be further subdivided into internal quantum efficiency (IQE) and external quantum efficiency (EQE). The IQE, defined as photon generation within the EML, is directly determined by the emitters, [16] while EQE refers to the numerical ratio of total photons emitting out of the device to the charge pairs injected. Since the photons are generated within and emitted out from the EML, the chemical structure of the emitter and the resulting properties can deeply influence the device efficiency. The traditional fluorescent emitters can only take advantages of singlet excitons for luminescence, with maximal IQE of roughly 25%. Given that out-coupling efficiency is normally 20%, the maximal EQE is only 5%, far below expectation. Phosphorescent OLEDs have the capability to reach 100% IQE, because phosphorescent emitters usually contain heavy atoms like iridium or platinum to harvest both, singlet and triplet excitons for phosphorescence through significant spin-orbit coupling, but the heavy metals usually bring about serious issues of comparable high costs and low long-term stability in OLEDs. [17] TTA fluorescent emitters can only reach a maximum IQE of 62.5% through conversion of two triplet excitons into one singlet exciton, and show mainly blue emission. [18] TADF materials, however, can harvest triplet Organic Light-Emitting Diodes Thermally activated delayed fluorescent (TADF) polymers are promising emitting materials to realize highly efficient, large-scale, and low-cost organic light-emitting diodes (OLEDs) since they exhibit various advantages such as heavy-metal-free structures, 100% theoretical internal quantum efficiency, and ease of large-area fabrication through solution process. At present,...

show abstract

Section: Introductionmentioning

confidence: 99%

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Wei

Voit

2018

Macromol. Rapid Commun.

122

100

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5] In view of exciton statistical rule, traditional fluorescent compounds can only utilize singlet excitons with 25% energy utilization to achieve electroluminescence. One of the most key components in OLEDs is emitting materials.…”

Section: Introductionmentioning

confidence: 99%

Solution-processed OLEDs based on phosphorescent PtAu₂ complexes with phenothiazine-functionalized acetylides

Zeng

Wang

et al. 2016

J. Mater. Chem. C

View full text Add to dashboard Cite

Two triphosphine-participated PtAu2 heterotrinuclear complexes with phenothiazine-functionalized acetylides were prepared. The crystal structural determination indicates that PtAu2 heterotrinuclear array is supported by double triphosphine ligands with substantial Pt-Au intermetallic contact in view of a short Pt-Au distance of 2.9549(4) Å. The PtAu2 complexes show moderate phosphorescent emission in fluid solution and powder state, but intense orange and yellow phosphorescence in doped PMMA films with quantum yields of 73.7% and 48.9%, respectively. The phosphorescence arises from an admixture of 3 [ (phenothiazine-acetylide)  * (triphosphine)] 3 LLCT and 3 [ (phenothiazine-acetylide)  p/s (PtAu2)] 3 LMCT triplet excited states. Utilizing blended host materials composed of both hole-transport TAPC and electron-transport OXD-7 doping with 8% phosphorescent PtAu2 complex as emitting layer, solution-processed OLEDs gave orange electroluminescence with the highest current efficiency (CE) of 35.4 cd A -1 and external quantum efficiency (EQE) of 18.7%. Scheme 1. Synthetic routes to PtAu2 complexes 1 and 2.

show abstract

“…Finally, device lifetime of type C-devices was investigated. Indeed, for future applications in displays and lighting, operational stability of devices is a critical issue [23,24]. Devices were operated at room temperature and at constant applied voltage starting from an initial luminance of 1500 cd/m 2 .…”

Section: Resultsmentioning

confidence: 99%

Organic Light-Emitting Diodes Based on Phthalimide Derivatives: Improvement of the Electroluminescence Properties

2018

View full text Add to dashboard Cite

Abstract:In this study, a phthalimide-based fluorescent material has been examined as a green emitter for multilayered organic light-emitting diodes (OLEDs). By optimizing the device stacking, a maximum brightness of 28,450 cd/m 2 at 11.0 V and a maximum external quantum efficiency of 3.11% could be obtained. Interestingly, OLEDs fabricated with Fluo-2 presented a 20-fold current efficiency improvement compared to the previous results reported in the literature, evidencing the crucial role of the device stacking in the electroluminescence (EL) performance of a selected emitter. Device lifetime was also examined and an operational stability comparable to that reported for a standard triplet emitter i.e., bis(4-methyl-2,5-diphenyl-pyridine)iridium(III) acetylacetonate [(mdppy) 2 Iracac] was evidenced.

show abstract

Recent progress in the use of fluorescent and phosphorescent organic compounds for organic light-emitting diode lighting

Cited by 51 publications

References 69 publications

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Solution-processed OLEDs based on phosphorescent PtAu₂ complexes with phenothiazine-functionalized acetylides

Organic Light-Emitting Diodes Based on Phthalimide Derivatives: Improvement of the Electroluminescence Properties

Contact Info

Product

Resources

About

Recent progress in the use of fluorescent and phosphorescent organic compounds for organic light-emitting diode lighting

Cited by 51 publications

References 69 publications

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Solution-processed OLEDs based on phosphorescent PtAu2 complexes with phenothiazine-functionalized acetylides

Organic Light-Emitting Diodes Based on Phthalimide Derivatives: Improvement of the Electroluminescence Properties

Contact Info

Product

Resources

About

Solution-processed OLEDs based on phosphorescent PtAu₂ complexes with phenothiazine-functionalized acetylides