共查询到20条相似文献,搜索用时 15 毫秒
1.
Purely Organic Thermally Activated Delayed Fluorescence Materials for Organic Light‐Emitting Diodes 下载免费PDF全文
The design of thermally activated delayed fluorescence (TADF) materials both as emitters and as hosts is an exploding area of research. The replacement of phosphorescent metal complexes with inexpensive organic compounds in electroluminescent (EL) devices that demonstrate comparable performance metrics is paradigm shifting, as these new materials offer the possibility of developing low‐cost lighting and displays. Here, a comprehensive review of TADF materials is presented, with a focus on linking their optoelectronic behavior with the performance of the organic light‐emitting diode (OLED) and related EL devices. TADF emitters are cross‐compared within specific color ranges, with a focus on blue, green–yellow, orange–red, and white OLEDs. Organic small‐molecule, dendrimer, polymer, and exciplex emitters are all discussed within this review, as is their use as host materials. Correlations are provided between the structure of the TADF materials and their optoelectronic properties. The success of TADF materials has ushered in the next generation of OLEDs. 相似文献
2.
Combined Inter‐ and Intramolecular Charge‐Transfer Processes for Highly Efficient Fluorescent Organic Light‐Emitting Diodes with Reduced Triplet Exciton Quenching 下载免费PDF全文
Chang‐Ki Moon Katsuaki Suzuki Katsuyuki Shizu Chihaya Adachi Hironori Kaji Jang‐Joo Kim 《Advanced materials (Deerfield Beach, Fla.)》2017,29(17)
Inter‐ and intramolecular charge‐transfer processes are combined using an exciplex‐forming host and a thermally activated delayed fluorescent dopant, for fabricating efficient fluorescent organic light‐emitting diodes along with the reduced efficiency roll‐off at high current densities. Extra conversion on the host from triplet exciplexes to singlet exciplexes followed by energy transfer to the dopant reduces population of triplet excitons on dopant molecules, thereby reducing the triplet exciton annihilations at high current densities. 相似文献
3.
Yuan‐Lan Zhang Quan Ran Qiang Wang Yuan Liu Christian Hnisch Sebastian Reineke Jian Fan Liang‐Sheng Liao 《Advanced materials (Deerfield Beach, Fla.)》2019,31(42)
Researchers have spared no effort to design new thermally activated delayed fluorescence (TADF) emitters for high‐efficiency organic light‐emitting diodes (OLEDs). However, efficient long‐wavelength TADF emitters are rarely reported. Herein, a red TADF emitter, TPA–PZCN, is reported, which possesses a high photoluminescence quantum yield (ΦPL) of 97% and a small singlet–triplet splitting (ΔEST) of 0.13 eV. Based on the superior properties of TPA–PZCN, red, deep‐red, and near‐infrared (NIR) OLEDs are fabricated by utilizing different device structure strategies. The red devices obtain a remarkable maximum external quantum efficiency (EQE) of 27.4% and an electroluminescence (EL) peak at 628 nm with Commission Internationale de L'Eclairage (CIE) coordinates of (0.65, 0.35), which represents the best result with a peak wavelength longer than 600 nm among those of the reported red TADF devices. Furthermore, an exciplex‐forming cohost strategy is adopted. The devices achieve a record EQE of 28.1% and a deep‐red EL peak at 648 nm with the CIE coordinates of (0.66, 0.34). Last, nondoped devices exhibit 5.3% EQE and an NIR EL peak at 680 nm with the CIE coordinates of (0.69, 0.30). 相似文献
4.
5.
Light‐Emitting Diodes: Efficient Vacuum‐Processed Light‐Emitting Diodes Based on Carbene–Metal–Amides (Adv. Mater. 35/2018) 下载免费PDF全文
Patrick J. Conaghan S. Matthew Menke Alexander S. Romanov Saul T. E. Jones Andrew J. Pearson Emrys W. Evans Manfred Bochmann Neil C. Greenham Dan Credgington 《Advanced materials (Deerfield Beach, Fla.)》2018,30(35)
6.
Organic Light‐Emitting Diodes: Achieving Nearly 30% External Quantum Efficiency for Orange–Red Organic Light Emitting Diodes by Employing Thermally Activated Delayed Fluorescence Emitters Composed of 1,8‐Naphthalimide‐Acridine Hybrids (Adv. Mater. 5/2018) 下载免费PDF全文
Weixuan Zeng Hsin‐Yu Lai Wei‐Kai Lee Min Jiao Yi‐Jiun Shiu Cheng Zhong Shaolong Gong Tao Zhou Guohua Xie Monima Sarma Ken‐Tsung Wong Chung‐Chih Wu Chuluo Yang 《Advanced materials (Deerfield Beach, Fla.)》2018,30(5)
7.
Patrick J. Conaghan S. Matthew Menke Alexander S. Romanov Saul T. E. Jones Andrew J. Pearson Emrys W. Evans Manfred Bochmann Neil C. Greenham Dan Credgington 《Advanced materials (Deerfield Beach, Fla.)》2018,30(35)
Efficient vacuum‐processed organic light‐emitting diodes are fabricated using a carbene–metal–amide material, CMA1. An electroluminescence (EL) external quantum efficiency of 23% is achieved in a host‐free emissive layer comprising pure CMA1. Furthermore external quantum efficiencies of up to 26.9% are achieved in host–guest emissive layers. EL spectra are found to depend on both the emissive‐layer doping concentration and the choice of host material, enabling tuning of emission color from mid‐green (Commission Internationale de l'Éclairage co‐ordinates [0.24, 0.46]) to sky blue ([0.22 0.35]) without changing dopant. This tuning is achieved without compromising luminescence efficiency (>80%) while maintaining a short radiative lifetime of triplets (<1 μs). 相似文献
8.
9.
10.
Inheriting the Characteristics of TADF Small Molecule by Side‐Chain Engineering Strategy to Enable Bluish‐Green Polymers with High PLQYs up to 74% and External Quantum Efficiency over 16% in Light‐Emitting Diodes 下载免费PDF全文
Guohua Xie Jiajia Luo Manli Huang Tianheng Chen Kailong Wu Shaolong Gong Chuluo Yang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(11)
11.
Degradation in organic light‐emitting diodes (OLEDs) is a complex problem. Depending upon the materials and the device architectures used, the degradation mechanism can be very different. In this Progress Report, using examples in both small molecule and polymer OLEDs, the different degradation mechanisms in two types of devices are examined. Some of the extrinsic and intrinsic degradation mechanisms in OLEDs are reviewed, and recent work on degradation studies of both small‐molecule and polymer OLEDs is presented. For small‐molecule OLEDs, the operational degradation of exemplary fluorescent devices is dominated by chemical transformations in the vicinity of the recombination zone. The accumulation of degradation products results in coupled phenomena of luminance‐efficiency loss and operating‐voltage rise. For polymer OLEDs, it is shown how the charge‐transport and injection properties affect the device lifetime. Further, it is shown how the charge balance is controlled by interlayers at the anode contact, and their effects on the device lifetime are discussed. 相似文献
12.
13.
Light‐Emitting Diodes: Highly Efficient Orange and Red Phosphorescent Organic Light‐Emitting Diodes with Low Roll‐Off of Efficiency using a Novel Thermally Activated Delayed Fluorescence Material as Host (Adv. Mater. 27/2015) 下载免费PDF全文
Hui Wang Lingqiang Meng Xingxing Shen Xiaofang Wei Xiuli Zheng Xiaopeng Lv Yuanping Yi Ying Wang Pengfei Wang 《Advanced materials (Deerfield Beach, Fla.)》2015,27(27):4104-4104
14.
High‐Performance Fluorescent Organic Light‐Emitting Diodes Utilizing an Asymmetric Anthracene Derivative as an Electron‐Transporting Material 下载免费PDF全文
Xiaozeng Song Minghan Cai Zhengyang Bin Tianyu Huang Lian Duan 《Advanced materials (Deerfield Beach, Fla.)》2018,30(26)
Fluorescent organic light‐emitting diodes with thermally activated delayed fluorescent sensitizers (TSF‐OLEDs) have aroused wide attention, the power efficiencies of which, however, are limited by the mutual exclusion of high electron‐transport mobility and large triplet energy of electron‐transporting materials (ETMs). Here, an asymmetric anthracene derivative with electronic properties manipulated by different side groups is developed as an ETM to promote TSF‐OLED performances. Multiple intermolecular interactions are observed, leading to a kind of “cable‐like packing” in the crystal and favoring the simultaneous realization of high electron‐transporting mobility and good exciton‐confinement ability, albeit the low triplet energy of the ETM. The optimized TSF‐OLEDs exhibit a record‐high maximum external quantum efficiency/power efficiency of 24.6%/76.0 lm W?1, which remain 23.8%/69.0 lm W?1 at a high luminance of even 5000 cd m?2 with an extremely low operation voltage of 3.14 V. This work opens a new paradigm for designing ETMs and also paves the way toward practical application of TSF‐OLEDs. 相似文献
15.
Achieving Nearly 30% External Quantum Efficiency for Orange–Red Organic Light Emitting Diodes by Employing Thermally Activated Delayed Fluorescence Emitters Composed of 1,8‐Naphthalimide‐Acridine Hybrids 下载免费PDF全文
Weixuan Zeng Hsin‐Yu Lai Wei‐Kai Lee Min Jiao Yi‐Jiun Shiu Cheng Zhong Shaolong Gong Tao Zhou Guohua Xie Monima Sarma Ken‐Tsung Wong Chung‐Chih Wu Chuluo Yang 《Advanced materials (Deerfield Beach, Fla.)》2018,30(5)
The combination of rigid acridine donor and 1,8‐naphthalimide acceptor has afforded two orange–red emitters of NAI‐DMAC and NAI‐DPAC with high rigidity in molecular structure and strongly pretwisted charge transfer state. Endowed with high photoluminescence quantum yields (ΦPL), distinct thermally activated delayed fluorescence (TADF) characteristics, and preferentially horizontal emitting dipole orientations, these emitters afford record‐high orange–red TADF organic light‐emitting diodes (OLEDs) with external quantum efficiencies of up to 21–29.2%, significantly surpassing all previously reported orange‐to‐red TADF OLEDs. Notably, the influence of microcavity effect is verified to support the record‐high efficiency. This finding relaxes the usually stringent material requirements for effective TADF emitters by comprising smaller radiative transition rates and less than ideal ΦPLs. 相似文献
16.
Shufen Chen Lingling Deng Jun Xie Ling Peng Linghai Xie Quli Fan Wei Huang 《Advanced materials (Deerfield Beach, Fla.)》2010,22(46):5227-5239
Organic light‐emitting diodes (OLEDs) have rapidly progressed in recent years due to their unique characteristics and potential applications in flat panel displays. Significant advancements in top‐emitting OLEDs have driven the development of large‐size screens and microdisplays with high resolution and large aperture ratio. After a brief introduction to the architecture and types of top‐emitting OLEDs, the microcavity theory typically used in top‐emitting OLEDs is described in detail here. Then, methods for producing and understanding monochromatic (red, green, and blue) and white top‐emitting OLEDs are summarized and discussed. Finally, the status of display development based on top‐emitting OLEDs is briefly addressed. 相似文献
17.
18.
Prediction and Design of Efficient Exciplex Emitters for High‐Efficiency,Thermally Activated Delayed‐Fluorescence Organic Light‐Emitting Diodes 下载免费PDF全文
Xiao‐Ke Liu Zhan Chen Cai‐Jun Zheng Chuan‐Lin Liu Chun‐Sing Lee Fan Li Xue‐Mei Ou Xiao‐Hong Zhang 《Advanced materials (Deerfield Beach, Fla.)》2015,27(14):2378-2383
19.
Sung Yong Byeon Dong Ryun Lee Kyoung Soo Yook Jun Yeob Lee 《Advanced materials (Deerfield Beach, Fla.)》2019,31(34)
The external quantum efficiency (EQE) of organic light‐emitting diodes (OLEDs) has been dramatically improved by developing highly efficient organic emitters such as phosphorescent emitters and thermally activated delayed fluorescent (TADF) emitters. However, high‐EQE OLED technologies suffer from relatively poor device lifetimes in spite of their high EQEs. In particular, the short lifetimes of blue phosphorescent and TADF OLEDs remain a big hurdle to overcome. Therefore, the high‐EQE approach harvesting singlet excitons of fluorescent emitters by energy transfer processes from the host or sensitizer has been explored as an alternative for high‐EQE OLED strategies. Recently, there has been a big jump in the EQE and device lifetime of singlet‐exciton‐harvesting fluorescent OLEDs. Recent progress on the materials and device structure is discussed herein. 相似文献
20.
Blocking Energy‐Loss Pathways for Ideal Fluorescent Organic Light‐Emitting Diodes with Thermally Activated Delayed Fluorescent Sensitizers 下载免费PDF全文
Dongdong Zhang Xiaozeng Song Minghan Cai Lian Duan 《Advanced materials (Deerfield Beach, Fla.)》2018,30(6)
Organic light‐emitting diodes (OLEDs) based on thermally activated delayed fluorescence‐sensitized fluorescence (TSF) offer the possibility of attaining an ultimate high efficiency with low roll‐off utilizing noble‐metal free, easy‐to‐synthesize, pure organic fluorescent emitters. However, the performances of TSF‐OLEDs are still unsatisfactory. Here, TSF‐OLEDs with breakthrough efficiencies even at high brightnesses by suppressing the competitive deactivation processes, including direct charge recombination on conventional fluorescent dopants (CFDs) and Dexter energy transfer from the host to the CFDs, are demonstrated. On the one hand, electronically inert terminal‐substituents are introduced to protect the electronically active core of the CFDs; on the other hand, delicate device structures are designed to provide multiple energy‐funneling paths. As a result, unprecedentedly high maximum external quantum efficiency/power efficiency of 24%/71.4 lm W?1 in a green TSF‐OLED are demonstrated, which remain at 22.6%/52.3 lm W?1 even at a high luminance of 5000 cd m?2. The work unlocks the potential of TSF‐OLEDs, paving the way toward practical applications. 相似文献