Bilayer-structure white organic light-emitting diode based on [Alq3:rubrene] and the electron transporting characteristics investigation using impedance spectroscopy

Mo, Bingjie; Zhang, Xiaowen; Li, Liming; Wang, Honghang; Xu, Jiwen; Wang, Hua; Wei, Bin

doi:10.1016/j.optlastec.2014.12.004

Cited by 13 publications

(3 citation statements)

References 17 publications

(33 reference statements)

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“…To further examine the influence of Y doping in the ZnO layer on the device electrical properties, we investigated the device characteristics with impedance spectroscopy. Impedance spectroscopy is a useful tool for studying interfacial electrical properties, such as carrier injection and transportation of devices, and has been widely utilized in the field of OLEDs and organic photovoltaics (OPVs) . The electrical properties of conductivity and resistivity as a function of frequency can be explained according to the impedance,

Z = R - jX

, where R is the real part and X is the imaginary part of the impedance.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Lifetime and Efficiency of Red Quantum Dot Light‐Emitting Diodes with Y‐Doped ZnO Sol–Gel Electron‐Transport Layers by Reducing Excess Electron Injection

et al. 2018

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Charge balance between electrons and holes, which are injected into the quantum dot (QD) emission layer (EML), is critical for realizing stable and efficient QD light‐emitting diodes (QLEDs). ZnO has been widely used as an electron‐transport layer (ETL) because of its superior performance compared to other metal oxides. However, nearly barrier‐free electron injection into the QD EML leads to spontaneous charge transfer and excess electron injection, resulting in reduced device performance. Here, to adjust electron–hole balance and thereby improve the lifetime and efficiency of QLEDs, we introduce an yttrium (Y)‐doped ZnO (YZO) ETL into QLEDs. The sol–gel processed YZO film, with a mobility that could be simply tuned by varying the Y concentration, provides enhanced charge‐transport balance by suppressing excess electron flow to the QD EML. Furthermore, YZO helps suppress QD charging and smooth the surface morphology. Applying the YZO ETL into the inverted‐structure QLED enables us to achieve color‐saturated red emission, an improved external quantum efficiency of up to 8.6%, and an eight times longer lifetime compared to the device with undoped ZnO. This result provides a simple method for enhancing the performance of QLEDs by easily controlling metal doping concentration in the sol–gel processed ZnO ETL.

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Z = R - jX

, where R is the real part and X is the imaginary part of the impedance.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Lifetime and Efficiency of Red Quantum Dot Light‐Emitting Diodes with Y‐Doped ZnO Sol–Gel Electron‐Transport Layers by Reducing Excess Electron Injection

et al. 2018

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“…With the parameter sets R 1 = 50 Ω, R 2 = 5.0 × 10 6 Ω, and C = 10 × 10 −9 F, where R 1 and R 2 are the estimated resistances of the ITO electrode and OLED, respectively, and C is a typical value [14], Equation (6) produces the solid line shown in Figure 3 with a variable parameter of A = 2.88 × 10 6 and 6.35 × 10 5 count C −1 for the ITO/TPD/Alq 3 /Al and ITO/CoPc/Alq 3 /Al devices, respectively. Equations (5) and (6) clearly indicate that ∆I also depends on the time of the reverse-bias application t. Figure 5 depicts the t −1 (i.e., 2f ) dependence of ∆I derived from Figure 2 together with the values calculated using the parameter sets in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Emission by Accumulated Charges at Organic/Metal Interfaces Generated during the Reverse Bias of Organic Light Emitting Diodes

Nozoe

Matsuda

2017

Applied Sciences

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A high frequency rectangular alternating voltage was applied to organic light emitting diodes (OLEDs) with the structure ITO/TPD/Alq 3 /Al and ITO/CoPc/Alq 3 /Al, where ITO is indium-tin-oxide, TPD is 4,4 -bis[N-phenyl-N-(m-tolyl)amino]biphenyl, CoPc is cobalt phthalocyanine, and Alq 3 is Tris(8-quinolinolato)aluminum, and the effect on emission of the reverse bias was examined. The results reveal that the emission intensity under an alternating reverse-forward bias is greater than that under an alternating zero-forward bias. The difference in the emission intensity (∆I) increased both for decreasing frequency and increasing voltage level of the reverse bias. In particular, the change in emission intensity was proportional to the voltage level of the reverse bias given the same frequency. To understand ∆I, this paper proposes a model in which an OLED works as a capacitor under reverse bias, where positive and negative charges accumulate on the metal/organic interfaces. In this model, the emission enhancement that occurs during the alternating reverse-forward bias is rationalized as a result of the charge accumulation at the organic/metal interfaces during the reverse bias, which possibly modulates the vacuum level shifts at the organic/metal interfaces to reduce both the hole injection barrier at the organic/ITO interface and the electron injection barrier at the organic/Al interface under forward bias.

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“…Rubrene and 9,10-diphenylanthracene are common molecules applied in organic light emission diodes (OLEDs) and glow sticks. The quantum efficiency of rubrene ,,− and 9,10-diphenylanthracene is much higher and more stable than that of luciferin. ,,− From the mechanism of chemiluminescence, the derivatives of diphenyl oxalate were the limitation to exciting rubrene and 9,10-diphenylanthracene. Chemiluminescence was able to keep stable light for more than 10 h with a sufficient amount of the derivatives (diphenyl oxalate).…”

Section: Introductionmentioning

confidence: 99%

Firefly-like Water Splitting Cells Based on FRET Phenomena with Ultrahigh Performance over 12%

Lai

Pan

2018

ACS Appl. Mater. Interfaces

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A firefly-like chemiluminescence reaction was utilized in a ZrO nanoparticle matrix of water splitting cells, where the chlorophyll of Lantana camara was used as the major photosensitizer to excite electrons to the conduction band of ZrO. The fluorescence resonance energy transfer (FRET) was induced by rubrene, a firefly-like chemiluminescence molecule, and Lantana camara chlorophyll combined with 9,10-diphenylanthracene. The ZrO nanoparticle film coated by the chlorophyll of Lantana camara and 9,10-diphenylanthracene under chemiluminescence irradiation in 1 M KHCO water solution demonstrated the highest photocurrent density (88.1 A/m) and the highest water splitting efficiency (12.77%).

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Bilayer-structure white organic light-emitting diode based on [Alq3:rubrene] and the electron transporting characteristics investigation using impedance spectroscopy

Cited by 13 publications

References 17 publications

Enhanced Lifetime and Efficiency of Red Quantum Dot Light‐Emitting Diodes with Y‐Doped ZnO Sol–Gel Electron‐Transport Layers by Reducing Excess Electron Injection

Enhanced Lifetime and Efficiency of Red Quantum Dot Light‐Emitting Diodes with Y‐Doped ZnO Sol–Gel Electron‐Transport Layers by Reducing Excess Electron Injection

Enhanced Emission by Accumulated Charges at Organic/Metal Interfaces Generated during the Reverse Bias of Organic Light Emitting Diodes

Firefly-like Water Splitting Cells Based on FRET Phenomena with Ultrahigh Performance over 12%

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