ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Yuanyuan Wang,Dawei Yang,Heng Zhang
Although high-performance quantum-dot light-emitting diodes (QLEDs) have been achieved, their stability is still limited due to the use of unstable PEDOT:PSS as the hole injection layer (HIL). Here, we developed a PEDOT:PSS-free QLED by using a binary PTAA:F4-TCNQ HIL. Because the PTAA, with a highest occupied molecular orbital (HOMO) level of ∼5.20 eV, can facilitate hole injection from ITO to the hole transport layer, and the F4-TCNQ can act as the electron acceptor dopant to improve the hole density and hole mobility of PTAA, the PTAA:F4-TCNQ HIL can exhibit excellent hole injection capability. As a result, the PEDOT:PSS-free QLED can exhibit a high EQE of 24.19% and an impressive brightness of 367,200 cd/m2, which are significantly higher than those of conventional QLEDs. Moreover, due to the improvement of device performance and the removal of PEDOT:PSS, the PEDOT:PSS-free QLED can also exhibit a high T95 operational lifetime of 4206 h at 1000 cd/m2 and an excellent T80 shelf lifetime of 207.41 h at 136400 cd/m2, which are about 1.6- and 3.3-fold those of conventional QLEDs, respectively. We believe that the demonstrated PEDOT:PSS-free QLED, with higher performance and stability, will promote the practical application of QLEDs in displays.
研究领域:
材料科学
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电子工程
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高影响因子
Advanced Materials Interfaces
·
2024
·
IF 4.3
Wei-Zhi Liu,Hong-Wei Duan,Shu-Guang Meng,Dong-Ying Zhou,Liang-Sheng Liao
The development of scalable and cost-effective solution processes for large-area quantum light-emitting diodes (QLEDs) remains a pressing challenge. In this work, the blade-coating process is explored for fabricating bottom-emitting QLEDs using a poly(3,4- ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) layer modified with methanol (MeOH) and polyethylene glycol (PEG). By incorporating MeOH into the PEDOT:PSS solution, a significant reduction in surface tension is achieved, resulting in thinner and more uniform films. The addition of PEG further enhanced the film quality by suppressing PEDOT aggregation and improving phase separation, which is confirmed via atomic force microscopy (AFM). These modifications not only enhanced the conductivity of the PEDOT:PSS film due to the conformation changes, but also improved energy level alignment, leading to improved hole-injecting properties and reduced driving voltages in QLED devices. Small-area QLEDs with the optimized PEDOT:PSS/MeOH/PEG layer demonstrated peak current efficiencies (CE) and external quantum efficiencies (EQE) comparable to those of spin-coated devices. The best performance is observed at a PEG concentration of 0.1 mg mL −1 , yielding a CE of 33.1 cd A −1 and an EQE of 26.0%. Additionally, large-area QLEDs (25 × 25 mm) fabricated with this approach showed uniform emission and high efficiencies, underscoring the potential of the blade-coating method for scalable production of high-performance QLEDs.
研究领域:
材料科学
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ORGANIC ELECTRONICS
·
2020
·
IF 3.31
Yaoyao Liu,Luhua Lan,Benchang Liu,Hong Tao,Min Li,Hua Xu,Jianhua Zou,Miao Xu,Lei Wang,Junbiao Peng,Yong Cao
Quantum dot light-emitting diodes (QLEDs) have received extensive academic and industrial attention for the exceptional properties of QDs including size-tunable emission wavelengths , narrow emission linewidths and inherent photo-physical stability. It is vital for the QLEDs performance to select appropriate hole transport materials due to the imbalance carrier injection caused by the higher electron mobility in most devices. In this paper, a small molecular material 1,1-bis [4-[N,N′-di (p-tolyl)amino]phenyl]-cyclohexane (TAPC) with high hole mobility was used to physically blend with poly-N-vinylcarbazole (PVK) as the hole transport layer (HTL) by solution processing. In the inverted red QLEDs, when the optimized mass ratio of the mixture HTL (2:1 of PVK:TAPC) was adopted, the device turn-on voltage drops from 4.0 V to 2.4 V, the maximum current efficiency (CE max ) reaches 19.3 cd/A, which is 50% higher than that of the standard devices (with only PVK as HTL), the maximum power efficiency (PE max ) significantly increases from 5.2 lm/W to 16.7 lm/W, increased by more than 3 times, the external quantum efficiency (EQE) reaches 45% enhancement from 8.7% to 12.6%, and the optimized device lifetime is enhanced by 4.5 times. The improvement of performances can be mainly attributed to the addition of TAPC with high hole mobility and suitable energy levels, and the unique charge generation between PVK:TAPC and hole injection layer (HIL) interface. The results demonstrate that the blending of the small-molecule and polymer hole transport materials will be a feasible approach to improve the performance in the QLEDs.
研究领域:
材料科学
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光电技术
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高影响因子
Science Advances
·
2024
·Vol. 10
·期 33
·
IF 11.7
Xitong Zhu,Xiao Luo,Yunzhou Deng,Huan Wei,Feng Peng,Lei Ying,Fei Huang,Yuanyuan Hu,Yizheng Jin
Quantum-dot light-emitting diodes (QLEDs) are solution-processed electroluminescence devices with great potential as energy-saving, large-area, and low-cost display and lighting technologies. Ideally, the organic hole-transport layers (HTLs) in QLEDs should simultaneously deliver efficient hole injection and transport, effective electron blocking, and robust electrochemical stability. However, it is still challenging for a single HTL to fulfill all these stringent criteria. Here, we demonstrate a general design of doping-bilayer polymer-HTL architecture for stabilizing high-efficiency QLEDs. We show that the bilayer HTLs combining the electrochemical-stable polymer and the electron-blocking polymer unexpectedly increase the hole injection barrier. We mitigated the problem by p-doping of the underlying sublayer of the bilayer HTLs. Consequently, green QLEDs with an unprecedented maximum luminance of 1,340,000 cd m−2 and a record-long operational lifetime (T95 lifetime at an initial luminance of 1000 cd m−2 is 17,700 hours) were achieved. The universality of the strategy is examined in various polymer-HTL systems, providing a general route toward high-performance solution-processed QLEDs.
研究领域:
材料科学
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电气工程
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光电子学
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Materials Today Communications
·
2024
·
IF 3.7
Zenan Zhang,Haotian Gu,Tenglong Sun,Yongfeng Liu,Muzhi Cai,Junjie Si,Gongxun Bai,Laurent Calvez,Shiqing Xu
Poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS) has emerged as a promising candidate for high-cost transparent conductive oxide (TCO) electrodes. However, achieving high conductivity in PEDOT:PSS typically requires treatment with strong acids, which presents inherent risks. In this study, we propose an alternative approach utilizing a mild methane sulfonic acid (MSA) treatment for PEDOT:PSS as a transparent conductive electrode (TCE). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses unveil heightened phase separation between PEDOT and PSS by MSA treatment, accompanied by structural modifications in PEDOT. Moreover, the interfacial morphology between the MSA-treated electrode and the hole injection layer underwent significant changes. It is precisely this improved interface morphology, combined with enhanced conductivity, that significantly improves the efficiency of the obtained TCO-free blue quantum dot light-emitting diode (QLED) by 300 % compared to the reference device. Finally, leveraging the high performance of the TCO-free blue QLEDs, we fabricate the above device on a yellow-emissive phosphors-in-glass substrate, enabling a white light-emitting LED (WLED) device. This experiment not only elucidates the structural changes in PEDOT:PSS under mild acid treatment but also introduces an innovative strategy for developing high-performance PEDOT:PSS electrodes.
研究领域:
材料科学
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光电工程
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MATERIALS RESEARCH BULLETIN
·
2023
·
IF 5.4
Meijing Ning,Ke Zhao,Lijia Zhao,Sheng Cao,Jialong Zhao,Yonghui Gao,Xi Yuan
ZnO nanoparticles (NPs) are considered the most promising materials for electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs). Herein, we employed a synergistic strategy of Mg doping and ZnMgO shell coating to modify the defect states and energy levels of ZnO NPs. Mg doping mitigated the exciton luminescence quenching caused by charge transfer. A ZnMgO shell was also applied to coat the Mg-doped ZnO (ZMO) NPs to passivate surface oxygen defects further. Consequently, QLEDs utilizing ZMO@ZnMgO ETL demonstrate external quantum efficiency and maximum current efficiency of 9.0 % and 11.5 cd A −1 . This work shows an effective defect passivation strategy to enhance the performance of red-emitting InP-based QLEDs.
研究领域:
材料科学
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光电技术
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2025
·Vol. 36
·期 14
·1-9
·
IF 2.8
Qu Xuan,Jiang Jing,Ding Ting,Wang Meng-Wei,Song Yin-Man,Gao Pei-Li,Huang Zi-Bin,Li Ming-En,Su Shi-Chen,Wang Shuang-Peng
Quantum dot light-emitting diodes (QLEDs) hold great potential for next-generation displays, offering outstanding efficiency and exceptional color purity. Nevertheless, their performance remains constrained by poor hole injection and device instability. In this study, a bilayer structure of NiO/NiO x :Mg is proposed for the hole injection layer (HIL) in QLEDs to address these challenges. This bilayer structure enhances the work function, facilitates hole injection, and thereby improves the performance of QLEDs. As a result, the optimized device exhibits nearly twice the current efficiency compared to its NiO-based counterpart, along with an extended T 50 lifetime—approximately eight times longer than that of the NiO-based device. Additionally, Mg doping effectively mitigates photoluminescence quenching in quantum dots, and capacitance–voltage analysis, along with other measurements, confirms the reduction of hole injection barriers. These results suggest that employing bilayer HILs significantly improves QLEDs performance, with possible applications in other optoelectronic devices like perovskite solar cells.
研究领域:
材料科学
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光电子学
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高影响因子
Light-Science & Applications
·
2022
·Vol. 11
·期 1
·1-10
·
IF 20.257
Yu Peng,Cao Sheng,Shan Yuliang,Bi Yuhe,Hu Yaqi,Zeng Ruosheng,Zou Bingsuo,Wang Yunjun,Zhao Jialong
InP-based quantum dot light-emitting diodes (QLEDs), as less toxic than Cd-free and Pb-free optoelectronic devices, have become the most promising benign alternatives for the next generation lighting and display. However, the development of green-emitting InP-based QLEDs still remains a great challenge to the environmental preparation of InP quantum dots (QDs) and superior device performance. Herein, we reported the highly efficient green-emitting InP-based QLEDs regulated by the inner alloyed shell components. Based on the environmental phosphorus tris(dimethylamino)phosphine ((DMA) 3 P), we obtained highly efficient InP-based QDs with the narrowest full width at half maximum (~35 nm) and highest quantum yield (~97%) by inserting the gradient inner shell layer ZnSe x S 1−x without further post-treatment. More importantly, we concretely discussed the effect and physical mechanism of ZnSe x S 1– x layer on the performance of QDs and QLEDs through the characterization of structure, luminescence, femtosecond transient absorption, and ultraviolet photoelectron spectroscopy. We demonstrated that the insert inner alloyed shell ZnSe x S 1− x provided bifunctionality, which diminished the interface defects upon balancing the lattice mismatch and tailored the energy levels of InP-based QDs which could promote the balanced carrier injection. The resulting QLEDs applying the InP/ZnSe 0.7 S 0.3 /ZnS QDs as an emitter layer exhibited a maximum external quantum efficiency of 15.2% with the electroluminescence peak of 532 nm, which was almost the highest record of InP-based pure green-emitting QLEDs. These results demonstrated the applicability and processability of inner shell component engineering in the preparation of high-quality InP-based QLEDs.
研究领域:
材料科学
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光电子学
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纳米技术
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高影响因子
ACS Applied Nano Materials
·
2022
·
IF 6.14
Yan Wang,Xinyao Shan,Yingjie Tang,Tianyu Liu,Binghan Li,Peng Jin,Kun Liang,Dingwei Li,Yang Michael Yang,Huaibin Shen,Bowen Zhu,Botao Ji
Developing techniques of advanced patterning for colloidal nanocrystals (NCs) is essential to construct high-performance electronic/optoelectronic devices. However, conventional NC patterning methods require complicated photolithography processes and/or delicately designed photocrosslinkers. Here, we develop a direct, photoresist-free method to pattern functional NCs while avoiding any photosensitive molecules. In our approach, the solubility of NCs is switched through cleaving native organic ligands under UV light exposure. Developing with the mother solvent produces fine patterns with feature sizes (as low as 10 μm) comparable to that of conventional photolithography. Importantly, the obtained patterns of NCs allow postpatterning ligand exchange. As representatives, we demonstrate patterned NC-based thin-film transistors (TFTs) and quantum dot light-emitting diodes (QLEDs). The In2O3 NC-based TFTs are turned from inactive to active using the patterning process and display substantially enhanced electronic performances upon ligand exchange with inorganic ligands. Furthermore, exquisite fluorescence quantum dot (QD) patterns are enabled. The QLEDs fabricated with ZnCl2-treated green QD patterns exhibit electroluminescence performances that are comparable to those of unpatterned QLEDs. Our strategy offers a powerful yet simple patterning technique for fabricating low-temperature thin-film electronics and optoelectronics, which is expected to be a versatile and extensible approach for solution-processed NC-based thin-film device manufacturing.
研究领域:
材料科学
·
电子工程
·
光学工程
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高影响因子
Laser & Photonics Reviews
·
2023
·Vol. 17
·期 5
·2200749
·
IF 11
Jinxing Zhao,Lijin Wang,Peiwen Lv,Fenghe Wang,Xu Li,Song Chen,Lei Qian,Aiwei Tang
Although cadmium (Cd)-based nanocrystals have enabled high-performance quantum-dot light-emitting diodes (QLEDs), their mass production is likely to be affected by environmental protection policies. Among all the potential Cd-free candidates, Cu-In-Zn-S (CIZS) nanocrystals (NCs) have attracted particular interests. Still, the performance of the corresponding LED is currently limited by imbalanced charge injection and luminescence quenching, which are both related to the ZnO-based electron transporting layer (ETL). This work demonstrates that ZnO nanoparticles (NPs) doped with Sn, Mg (Zn 1− x − y Sn x Mg y O), and passivated with Cl are promising to resolve the above issues. All-solution-processed QLEDs based on Cd-free CIZS NCs are fabricated by using Zn 0.9 Sn 0.1 O NPs as the ETL, and the peak external quantum efficiency (EQE max ) was nearly twice that of ZnO (EQE max = 1.74%). The main reason is that the incorporation of Sn can reduce the conductivity of ZnO by an order of magnitude. Combining the advantages of Zn 0.9 Sn 0.1 O, Zn 0.8 Sn 0.1 Mg 0.1 O@Cl NPs are designed by the co-doping of Mg and Cl passivation. The EQE max and current efficiency based on Zn 0.8 Sn 0.1 Mg 0.1 O and Zn 0.8 Sn 0.1 Mg 0.1 O@Cl as ETLs are further increased to 4.84%, 14.00 cd A −1 and 5.53%, 15.99 cd A −1 , respectively. The positive effects of Mg ions can remarkably optimize energy level structure to balance charge injection, while Cl can further passivate defects. The findings offer a new guideline for developing Cd-free light-emitting diodes.
研究领域:
材料科学
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光电技术
·
纳米技术
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高影响因子
ACS Applied Electronic Materials
·
2021
·
IF 3.314
Haodong Tang,Siqi Jia,Shihao Ding,Pai Liu,Jingrui Ma,Xiangtian Xiao,Xiangwei Qu,Haochen Liu,Hongcheng Yang,Bing Xu,Wei Chen,Guangyu Li,Zoe Pikramenou,Carl Anthony,Kai Wang,Xiao Wei Sun
Ink-jet printing is a promising deposition technology, which is capable of large-area fabrication and mask-free patterning. For ink-jet-printed quantum dot (QD) light-emitting diodes (LEDs), the QDs are commonly dissolved in a mixture of solvent and thickener ink system. However, the hole transport layer could be eroded by this QD ink, leading to a rough surface morphology and resulting in the leakage of carriers and low device performance. This phenomenon was first and directly observed by using an atomic force microscope and a cross-sectional scanning electron microscope. We, therefore, redesigned the annealing process of the hole transport layer to achieve an optimized smooth surface with a reduced number of defects for ink-jet-printed QD LEDs (QLEDs). Optimized morphology brings back a maximum luminance of over 30,000 cd/m2 and an external quantum efficiency of 7.52% for the ink-jet-printed red QLEDs using CdSe QDs, which are comparable to those of the spin-coated device. Moreover, the operation lifetime of the ink-jet-printed device is also enhanced by the restored surface morphology. An enhanced T50 lifetime of the ink-jet-printed device at 1000 cd/m2 is improved from 26 to 127 h, which converted to a long T50 lifetime of 8013 h, when operated at 100 cd/m2.
研究领域:
材料科学
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电子工程
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高影响因子
ACS Photonics
·
2018
·
IF 6.88
Fei Chen,Zhenyang Liu,Zhongyuan Guan,Zheming Liu,Xu Li,Zhenbo Deng,Feng Teng,Aiwei Tang
Colloidal ZnO nanoparticles (NPs) are widely used as an electron-transporting layer (ETL) in the solution-processed quantum-dot light-emitting diodes (QD-LEDs). However, the inherent drawbacks including surface defect sites and unbalanced charge injection prevent the device from realizing their further performance enhancement. In this work, a series of Mg doped ZnO (ZnO:Mg) and chloride-passivated ZnO (Cl@ZnO) NPs were synthesized by using a solution-precipitation strategy, and they exhibited tunable optical bandgaps and upward-shift of conduction-band maximum (CBM). Solution-processed QD-LEDs based on cadmium-free Cu-In-Zn-S/ZnS (CIZS/ZnS) nanocrystals (NCs) were fabricated by using ZnO:Mg and Cl@ZnO NPs as the ETLs, whose maximum peak external quantum efficiency (EQE) was nearly twice as high as that of QD-LEDs using ZnO NPs as the ETL (EQE = 1.54%). To take advantage of the benefits of ZnO:Mg and Cl@ZnO NPs, Cl@ZnO:Mg NPs were developed through the integration of Mg doping and Cl-passivation. Surprisingly, the cadmium-free QD-LEDs with the Cl@ZnO:Mg NPs as the ETL exhibited a maximum peak EQE of 3.72% and current efficiency of 11.08 cd A–1, which could be enhanced to be 4.05% and 12.17 cd A–1 by optimizing the Cl amount, respectively. The positive effects of the Mg doping and Cl-passivation on the cadmium-free QD-LEDs are primarily ascribed to the reduced electron injection barrier of ETL/the emitting layer interface and slower electron mobility, which can be verified by the ultraviolet photoelectron spectroscopy (UPS) measurements and current density–voltage characteristics of electron-only devices.
研究领域:
材料科学
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光电领域
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高影响因子
危险品化学品经营许可证（带存储）