Article
Biochemistry & Molecular Biology
Zhiwei Peng, Yuhan Gao, Guohua Xie
Summary: PQDs have low-conductive ligands and defects in devices, requiring careful management of charge injection and transport for optimal electroluminescent performances. This study found that doping p-dopants into the hole transporting layer can improve electroluminescent performances in LED devices, with F4-TCNQ showing a 27% improvement in peak external quantum efficiency. Capacitance and transient electroluminescent measurements were used to analyze interactions in the doped HTL and at the interface between the HTL and PQDs.
Article
Nanoscience & Nanotechnology
Qiangqiang Wang, Xuanyu Zhang, Lei Qian, Chaoyu Xiang
Summary: Perovskite quantum dot light-emitting diodes (QLEDs) have potential for next-generation displays. The electron-accepting property of poly-[bis-(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) leads to the charging of quantum dot (QD) films, resulting in imbalance of charge injection and increased nonradiative recombination, affecting the QLEDs performance. This study compared two polymers, poly-(methyl methacrylate) (PMMA) and poly-(vinylpyrrolidone) (PVP), as hole interface buffer layers for QD films. The devices with PMMA achieved a maximum external quantum efficiency of 20.71%.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Shiyun Lei, Yuanyuan Xiao, Kanglin Yu, Biao Xiao, Ming Wan, Liyong Zou, Qingliang You, Renqiang Yang
Summary: This study investigates the hole injection mechanism in quantum dot light-emitting diodes (QLEDs) through a combination of experiments and simulations. It reveals that applied bias reduces the barrier height, facilitating hole injection and confining electrons within the quantum dots. The research also demonstrates that thermally assisted tunneling is the predominant pathway for hole injection. This study is significant for understanding the hole injection mechanism in QLEDs.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Engineering, Environmental
Qiqing Lu, Jingkun Wang, Yanqin Miao, Yuanyuan Guo, Guoliang Wang, Jianhua Dong, Min Zhao, Hua Wang
Summary: In this work, Ti3C2Tx-MXene nanosheets were successfully synthesized and used as hole injection layers in organic light-emitting diodes (OLEDs). The Ti3C2Tx-MXene nanosheets-based devices showed lower turn-on voltage and higher current efficiency, power efficiency, and external quantum efficiency compared to PEDOT:PSS-based reference devices. Furthermore, blue and red devices with Ti3C2Tx-MXene nanosheets as hole injection layers also demonstrated significantly improved efficiency, demonstrating the universal applicability of Ti3C2Tx-MXene nanosheets in OLEDs as hole injection materials.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Chemistry, Physical
Wanqi Ren, Kyung Rock Son, Tae Geun Kim
Summary: Blue TADF top-emission organic light-emitting diodes (OLEDs) with a second-order microcavity structure exhibit high external quantum efficiency (-20.2%) and narrow full width at half maximum (29 nm) by incorporating a Ni-doped SiO2 buffer layer that balances injection charges. The wide bandgap of SiO2 prevents rapid hole injection from the anode and modifies the anode-organic layer interface, while tuning of the Ni doping concentration reduces the turn-on voltage of the device through co-sputtering. The charge balance mechanism is elucidated by analyzing tunneling effects across the buffer layer and the bonding states of Ni atoms in the SiO2 film. This study can promote the development of TADF top-emission devices with high efficiency and color purity.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Seung-Gyun Choi, Hae-Jun Seok, Seunghyun Rhee, Donghyo Hahm, Wan Ki Bae, Han-Ki Kim
Summary: A novel V2O5 film was developed in this study to replace traditional PEDOT:PSS or solution-processed metal oxide HIL in QLEDs. By optimizing the sputtering conditions and oxygen flow rate, the V2O5 film achieved high optical transparency and a suitable work function, resulting in excellent performance of QLEDs.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Xinyu Shen, Hua Wu, Xiaoyu Zhang, Meili Xu, Junhua Hu, Jinyang Zhu, Bin Dong, William W. Yu, Xue Bai
Summary: The all-solution process for inorganic perovskite nanocrystals (PNCs) LEDs shows great potential for new-generation illumination and displays, but the challenge lies in the injection barriers and charge injection imbalance. The introduction of CBP into the hole transport layer (HTL) efficiently modulates the charge carrier mobility and energy level, resulting in barrier-free charge injection and optimal performance for solution-processed PNC LEDs. The luminance of red LEDs reaches 2990 cd m(-2) and the external quantum efficiency achieves 8.1%, with improved turn-on voltage and roll-off due to more balanced charge injection.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Apostolis Verykios, Giorgos Pistolis, Lambros Bizas, Charalambos Tselios, Dimitris Tsikritzis, Stella Kennou, Christos L. Chochos, Dionysis E. Mouzakis, Panagiotis N. Skandamis, Abd Rashid bin Mohd Yusoff, Leonidas C. Palilis, Panagiotis Argitis, Maria Vasilopoulou, Anastasia Soultati
Summary: In this study, a simple and effective approach was proposed to modify the optoelectronic properties of PEDOT:PSS through the addition of TPS salts, resulting in improved hole injection and transport in OLEDs. The composite film PEDOT:PSS:TPSTriflate showed the highest luminous and power efficiency among all tested films, attributed to the increased conductivity and the formation of an interface exciplex between TPS-Triflate and the emissive copolymer.
ORGANIC ELECTRONICS
(2021)
Article
Nanoscience & Nanotechnology
Han Bin Cho, Ju Yeon Han, Ha Jun Kim, Noolu Srinivasa Manikanta Viswanath, Yong Min Park, Jeong Wan Min, Sung Woo Jang, Heesun Yang, Won Bin Im
Summary: Quantum dot light-emitting diodes (QLEDs) are promising for display applications. Polyethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) is commonly used as a hole injection layer (HIL) material due to its high conductivity and work function. However, PEDOT:PSS-based QLEDs have a high energy barrier for hole injection, resulting in low device efficiency. Here, we demonstrate a bilayer-HIL using VO2 and a PEDOT:PSS-based QLED, which shows an 18% external quantum efficiency (EQE), 78 cd/A current efficiency (CE), and 25,771 cd/m(2) maximum luminance. This is compared to the PEDOT:PSS-based QLED with an EQE of 13%, CE of 54 cd/A, and maximum luminance of 14,817 cd/m(2). The increase in EQE is attributed to the reduction in the energy barrier between indium tin oxide (ITO) and PEDOT:PSS by the insertion of a VO(2) HIL. Therefore, our results demonstrate the effectiveness of a bilayer-HIL in increasing the EQE in QLEDs.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
Shanshan Liang, Yunqi Wang, Hui Qi, Shujie Wang, Zuliang Du
Summary: The dual hole injection structure fabricated through the introduction of Ti3C2Tx film significantly enhances the external quantum efficiency of blue QLEDs. The modified Ti3C2Tx devices exhibit a 67% increase in peak EQE compared to the reference devices. This improvement can be attributed to the reduced energy barrier between ITO and PEDOT:PSS and the enhanced electrical stability of the ITO/PEDOT:PSS interface due to the Ti3C2Tx hole injection layer.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Chemistry, Physical
Maopeng Xu, Desui Chen, Jian Lin, Xiuyuan Lu, Yunzhou Deng, Siyu He, Xitong Zhu, Wangxiao Jin, Yizheng Jin
Summary: Researchers developed a set of NiOx HILs with controlled work functions for QLEDs, finding that using HILs with higher work functions can improve efficiency roll-off and operational stability.
Article
Chemistry, Physical
Maopeng Xu, Desui Chen, Jian Lin, Xiuyuan Lu, Yunzhou Deng, Siyu He, Xitong Zhu, Wangxiao Jin, Yizheng Jin
Summary: Researchers developed a new type of hole-injection layer with controlled work functions to improve the efficiency and stability of quantum-dot light-emitting diodes (QLEDs). The study found that hole-injection layers with higher work functions can enhance the efficiency and lifetime of the devices. This research provides important guidance for the future design of QLEDs.
Article
Multidisciplinary Sciences
Shofu Matsuda, Chikara Itagaki, Kyoya Tatsuguchi, Masamichi Ito, Hiroto Sasaki, Minoru Umeda
Summary: This study investigates the effect of Au/fullerene-doped TPA interface on efficient hole injection, finding that using C-70 as a dopant can significantly reduce the hole injection barrier. The ion-dipole interaction between TPA and fullerenes is considered to play a role in reducing the barrier height based on cyclic voltammetry.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Multidisciplinary
Bochen Liu, Yue Guo, Qiang Su, Yunfeng Zhan, Zhao Chen, Yang Li, Baogui You, Xiaonan Dong, Shuming Chen, Wai-Yeung Wong
Summary: A new strategy is developed to synthesize red, green, and blue quantum dots using CdZnS as the outermost shell. The inner ZnS and ZnSe shells confine the excitons inside the QD cores, while the CdZnS shell reduces the energy barrier for hole injection, resulting in high-performance QLEDs.
Article
Chemistry, Physical
Jeong Ha Hwang, Junmo Kim, Byong Jae Kim, Myeongjin Park, Yong Woo Kwon, Myungchan An, Dong Yeol Shin, Jae Min Jeon, Jun Young Kim, Wonho Lee, Jaehoon Lim, Donggu Lee
Summary: This study introduces a multilayered hole transport layer structure to enhance the efficiencies and lifetimes of quantum dot light-emitting diodes. QD-LEDs with optimized HTL exhibit improved performance and long lifetimes.
APPLIED SURFACE SCIENCE
(2021)
