Solution-Processed Metal-Oxide p–n Charge Generation Junction for High-Performance Inverted Quantum-Dot Light-Emitting Diodes

Kim, Hyo‐Min; Kim, Jeonggi; Cho, Sinyoung; Jang, Jin

doi:10.1021/acsami.7b14584

Cited by 28 publications

(22 citation statements)

References 28 publications

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“…Figure shows the schematic device structure and the energy band diagram of blue QLEDs. Various organic materials such as poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)‐benzidine] (poly‐TPD); 4,4′‐bis(carbazole‐9‐yl)biphenyl (CBP); 4,4′,4″‐tri(9‐carbazoyl)‐triphenylamine (TcTa); and N,N′‐dicarbazolyl‐3,5‐benzene (mCP) have been used as HTLs for QLEDs . For appropriate HTLs, the materials should have deep‐lying HOMO levels and high hole mobility so that hole injection is efficient.…”

Section: Resultsmentioning

confidence: 99%

“…Various organic materials such as poly[N,N 0 -bis(4-butylphenyl)-N,N 0 -bis(phenyl)-benzidine] (poly-TPD); 4,4 0 -bis(carbazole-9-yl)biphenyl (CBP); 4,4 0 ,4″tri(9-carbazoyl)-triphenylamine (TcTa); and N,N 0dicarbazolyl-3,5-benzene (mCP) have been used as HTLs for QLEDs. 14,16,[24][25][26][27] For appropriate HTLs, the materials should have deep-lying HOMO levels and high hole mobility so that hole injection is efficient. In addition, the HTLs also function as electron blocking layer, and therefore, they should have low LUMO levels to block the excess electrons overflowing from the QDs.…”

Section: Introductionmentioning

confidence: 99%

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The influence of the hole transport layers on the performance of blue and color tunable quantum dot light‐emitting diodes

Huang

et al. 2018

J Soc Info Display

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The performance of the blue quantum dot light‐emitting diodes (QLEDs) is largely affected by the hole transport layers (HTLs). As a consequence of the deep valance band level of blue quantum dots (QDs), hole injection is relatively difficult in blue QLEDs. To favor the hole injection, HTLs with high hole mobility and deep‐lying highest occupied molecular orbital level are desired. In this work, various HTLs and their influence on the performance of blue QLEDs are demonstrated. Devices with poly(N‐vinylcarbazole) (PVK) HTL exhibit the highest external quantum efficiency while devices with poly[9,9‐dioctylfluorene‐co‐N‐(4‐(3‐methylpropyl))‐diphenylamine] (TFB) exhibit the lowest driving voltage. By combining the advantages of PVK and TFB, the blue QLEDs with TFB/PVK bilayered HTL simultaneously exhibit a low driving voltage of 2.6 V and a high external quantum efficiency of 5.9%. Moreover, the exciplex emission at the interface of HTL/QDs is also observed, and the emission intensity can be tuned by modulating the hole injection. By utilizing PVK doped with 25% poly(3‐hexylthiophene) (P3HT) as HTL, exciplex emission is significantly enhanced at low driving voltage while QD emission is dominant at high driving voltage. By combining the exciplex emission and the QD emission, the emission color can be effectively tuned from red to blue as the driving voltage changing from 2 to 10 V.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The influence of the hole transport layers on the performance of blue and color tunable quantum dot light‐emitting diodes

Huang

et al. 2018

J Soc Info Display

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“…As a demonstration of the resolution enabled by this measurement method, we analyze another sample consisting of a copper oxide CuO 2 / zinc oxide ZnO thin-film p/n junction deposited on a fluorinedoped tin oxide (FTO) conducting glass. Such composite oxide materials find application in sensing [20], energy conversion [21,22] and lighting [23], and their nanoscale characterization is needed for understanding their functionality. Figure 3(a) shows that the junction of the two semiconductors presents a typical diode-like IVC, with current flowing only for positive applied bias (orange curve).…”

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confidence: 99%

Fast Multifrequency Measurement of Nonlinear Conductance

et al. 2019

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We describe a phase-coherent multifrequency lock-in measurement technique that uses the inverse Fourier transform to reconstruct the nonlinear current-voltage characteristic (IVC) of a nanoscale junction. The method provides for a separation of the galvanic and displacement currents in the junction, and easy cancellation of the parasitic displacement current from the measurement leads. These two features allow us to overcome traditional limitations imposed by the low conductance of the junction and high capacitance of the leads, thus providing an increase in measurement speed of several orders of magnitude. We demonstrate the method in the context of conductive atomic force microscopy, acquiring IVCs at every pixel while scanning at standard imaging speed.The sensitive measurement of small currents in nanometer-scale junctions is a central problem in modern experimental physics. Characterization of numerous novel materials and devices, in applications ranging from topological quantum computers [1, 2] to energy harvesting and energy conversion [3][4][5][6][7][8][9][10], struggles with the same basic limitations imposed by the small measurement current and the large stray capacitance of the macroscopic leads. We describe how to circumvent these limitations using phase-coherent multifrequency lock-in measurement and inverse Fourier transform to achieve a dramatic improvement in the speed of measurement, or alternatively, in the signal-to-noise ratio at the same measurement speed. In addition, our frequency-domain approach allows for active cancellation of parasitic current due to the lead capacitance and it provides for unambiguous separation of the galvanic and displacement currents flowing in the nanoscale junction.One area where this improvement is particularly useful is scanning probe microscopy (SPM), where a measurement of the nonlinear current-voltage characteristic (IVC) is desired at each tip location. In scanning tunneling microscopy (STM) the IVC allows for mapping energy dependence of the local density of electronic states [11]. In conducting atomic force microscopy (AFM) it can be used to map energy-conversion efficiency in photoactive nanocomposite materials [12]. Due to the aforementioned limitations, present-day SPM has two basic modes of operation. In imaging mode the current is measured while scanning the surface with a constant tip-sample voltage, quickly generating an image but with only limited information. Multiple scans at different bias are required to get the full IVC, greatly increasing measurement time and introducing problems due to instrument drift and tip wear. In spectroscopic mode the IVC is recorded at each tip position, but the voltage must be swept slowly so as to minimize displacement current in the parallel capacitance of the measurement leads. This large background current puts a limit on the achievable gain and sensitivity of current measurement, and the slow sweep greatly limits the speed of the scan, or equivalently spatial resolution in a given measurement time. We demonstra...

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“…We recently reported Li:CuO/Li:ZnO (p-type oxide/n-type oxide) as the solution-processed CGJ. 6 However, the p-type oxide Li:CuO requires a long-time and high-temperature annealing process (250 o C for 1 hour), whereas n-type Li:ZnO requires annealing process at 160 o C for 10 min. For tandem QLEDs with Li:CuO/Li:ZnO as CGJ, the QD EML is damaged by long-time and high-temperature annealing process of p-type oxide Li:CuO, leading to the poor device performance.…”

Section: Introductionmentioning

confidence: 99%

47‐3: AMQLED Display with Highly Efficient Oxide N‐P Charge Generation Junction

Kim¹,

Kim²,

Lee³

et al. 2019

Symp Digest of Tech Papers

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We have developed high efficiency tandem quantum-dot lightemitting diode (QLED) by using oxide n-p charge generation junction (CGJ). The tandem QLED with oxide n-p CGJ exhibits the current efficiency as high as over 120 cd A -1 . The oxide n-p CGJ shows good Ohmic behavior under forward and reverse bias. It is obvious that the reverse current density is nearly equal to the forward current density, which suggest the efficient charge generation in the oxide n-p CGJ. In this work, we demonstrated a 4-inch AMQLED display using high efficiency tandem QLED with oxide n-p CGJ. Author KeywordsHigh efficiency, quantum-dot light-emitting diodes, oxide n-p CGJ, tandem structure, 4-inch AMQLED.

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Solution-Processed Metal-Oxide p–n Charge Generation Junction for High-Performance Inverted Quantum-Dot Light-Emitting Diodes

Cited by 28 publications

References 28 publications

The influence of the hole transport layers on the performance of blue and color tunable quantum dot light‐emitting diodes

The influence of the hole transport layers on the performance of blue and color tunable quantum dot light‐emitting diodes

Fast Multifrequency Measurement of Nonlinear Conductance

47‐3: AMQLED Display with Highly Efficient Oxide N‐P Charge Generation Junction

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