Large area organic light emitting diodes with multilayered graphene anodes

Moon, Jaehyun; Hwang, Ji Hyun; Choi, Hong Kyw; Kim, Taek Yong; Choi, Sung‐Yool; Joo, Chul Woong; Han, Jun; Shin, Jong-Yeol; Lee, Bong Joon; Cho, Doo Hee; Huh, Jin Woo; Park, Seung Koo; Cho, Nam Sung; Chu, Hye Yong; Lee, Jeong Ik

doi:10.1117/12.928065

Cited by 3 publications

(4 citation statements)

References 13 publications

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“…The efficiency can be enhanced by adjusting the total thickness of organics to be an integer multiple of the characteristic wavelength of the emitter. 6 To induce the microcavity enhancement effect, reflectance of the organic/electrode strongly matters. If the reflectance is low, it is difficult to induce the microcavity effect.…”

Section: Resultsmentioning

confidence: 99%

“…Because of the thinness of the organic layers, internal interference or microcavity can influence the efficiency of OLEDs. The efficiency can be enhanced by adjusting the total thickness of organics to be an integer multiple of the characteristic wavelength of the emitter . To induce the microcavity enhancement effect, reflectance of the organic/electrode strongly matters.…”

Section: Resultsmentioning

confidence: 99%

“…Graphene is a two-dimensional carbon material in which carbon atoms are arranged in a planar hexagonal lattice. Multilayered polycrystalline graphene films grown by a chemical vapor deposition (CVD) method possess high optical transparency ( T ≈ 83%) in the visible range and acceptable sheet resistance (∼150 Ω/sq), which is suitable for optoelectronic applications. , Presumably, because the work function of graphene (∼4.6 eV) is similar to that of indium tin oxide (ITO), it has been predominantly investigated as a transparent anode in organic light-emitting diodes (OLEDs). − In this work, we investigate the technical possibility of using graphene as a cathode material. Our motivation stemmed from the burgeoning active matrix (AM)-OLED display applications in TV, mobile display, and virtual reality gears.…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Understanding of Improved Performance of Graphene Cathode Inverted Organic Light-Emitting Diodes by Photoemission and Impedance Spectroscopy

Moon

Cho

Maeng

et al. 2018

ACS Appl. Mater. Interfaces

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Modification of multilayer graphene films was investigated for a cathode of organic light-emitting diodes (OLEDs). By doping the graphene/electron transport layer (ETL) interface with Li, the driving voltage of the OLED was reduced dramatically from 24.5 to 3.2 V at a luminance of 1000 cd/m. The external quantum efficiency was also enhanced from 3.4 to 12.9%. Surface analyses showed that the Li doping significantly lowers the lowest unoccupied molecular orbital level of the ETL, thereby reducing the electron injection barrier and facilitating electron injection from the cathode. Impedance spectroscopy analyses performed on electron-only devices (EODs) revealed the existence of distributed trap states with a well-defined activation energy, which is successfully described by the Havriliak-Negami capacitance functions and the temperature-independent frequency dispersion parameters. In particular, the graphene EOD showed a unique high-frequency feature as compared to the indium tin oxide one, which could be explained by an additional parallel capacitance element.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanistic Understanding of Improved Performance of Graphene Cathode Inverted Organic Light-Emitting Diodes by Photoemission and Impedance Spectroscopy

Moon

Cho

Maeng

et al. 2018

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…As an ordinary course, graphene and multilayered graphene have been experimented in a variety of applications. As being thin, electrically conductive, optically transparent and mechanically flexible, graphene has gained extensive attention as a possible replacement for indium tin oxide (ITO), which has been so far dominantly used as the material for anode or transparent electrode in OLEDs [5][6][7]. Potentially, due to its thinness, electrical conductivity and mechanical compliance, graphene films can be used in various flexible electronics.…”

Section: Introductionmentioning

confidence: 99%