Article
Chemistry, Multidisciplinary
Haifa Wu, Guoliang Wang, Daqing Zhang, Xin Jin, Xin Luo, Shiyan Guo, Haitao Zhou, Yanqin Miao, Jinhai Huang, Jianhua Su
Summary: This paper reports two new bipolar host materials with excellent stability and appropriate energy levels, which have great potential in organic light-emitting diode (OLED) applications.
NEW JOURNAL OF CHEMISTRY
(2022)
Article
Materials Science, Multidisciplinary
Sook Hee Jeong, Seung Chan Kim, Jun Yeob Lee
Summary: In this study, two carbazole-benzonitrile-based bipolar hosts, 3-CzPB and 4-CzPB, were proposed to improve the efficiency of blue phosphorescent organic light-emitting diodes (PhOLEDs). The efficient hole and electron transport properties of these hosts demonstrated their effective bipolar host characteristics. Blue PhOLEDs using the 3-CzPB host achieved high external quantum efficiencies in sky-blue and deep-blue devices, and 3-CzPB-hosted blue TADF and multi-resonance TADF devices also achieved high external quantum efficiencies. This study highlights the potential use of the 3-CzPB host as a universal host for blue organic light-emitting diodes.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Haonan Zhao, Jongchan Kim, Kan Ding, Mina Jung, Yongxi Li, Harald Ade, Jun Yeob Lee, Stephen R. Forrest
Summary: By incorporating a sterically bulky, electron-transporting host material into a conventional single host-guest emissive layer, the phase separation of the host matrix can be suppressed, leading to improved efficiency and operational lifetime of deep-blue phosphorescent organic light-emitting diodes (PHOLEDs). This bulky host allows for homogeneous mixing of the emissive layer molecules while preventing single host aggregation and nonradiative recombination. The controlled amorphous phase morphology of the mixed-host device reduces nonradiative exciton decay and enhances external quantum efficiency by 120 +/- 6% compared to a similar single-host device. Additionally, the mixed host facilitates the conduction of both charge carriers, reducing the probability of exciton annihilation and doubling the operational lifetime of deep-blue PHOLEDs.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Sandhya Rani Nayak, Shahnawaz, Iram Siddiqui, Jwo-Huei Jou, Sabita Patel, Sivakumar Vaidyanathan
Summary: A series of purposefully designed and synthesized luminophores showed deep blue emission and good thermal stability. They can be used in optoelectronics and selective detection of nitroaromatic compounds, as well as hosts for phosphorescent organic light-emitting diodes (PhOLEDs). Additionally, the luminophores can be used as emitters for fluorescent OLEDs and hosts for triplet dopants in PhOLEDs.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Applied
Ting Zhang, Min Zhu, Jiuyan Li, Yuyang Zhang, Xuchun Wang
Summary: By designing bipolar host materials with high triplet energies and bipolar charge transporting abilities, high efficiencies and slow efficiency roll-off were achieved in blue and green PhOLEDs, demonstrating high practical value for commercial applications.
Article
Chemistry, Applied
Yu Zheng, Zhijun Wang, Ziting Zhong, Xianhui Wang, Xin Jiang Feng, Gang He, Zujin Zhao, Hua Lu
Summary: In this study, a stable host TSPiF was designed and synthesized, leading to highly efficient phosphorescence organic light-emitting diodes. The green device exhibited excellent performance, while the blue device showed remarkable efficiencies at high doping concentrations.
Article
Chemistry, Multidisciplinary
Kai Song, Jiuyan Li, Di Liu, Ying Lan, Chen Wu, Botao Liu, Chunlong Shi
Summary: Three novel compounds were developed as bipolar host materials for OLEDs, with BCz and CNPy as the transporting groups. The molecular conformation, triplet energy, and charge transporting abilities varied depending on the linking style. Among them, o-CNPyBCz exhibited the highest triplet energy and more balanced charge transporting ability, making it suitable for sky blue and green OLEDs with excellent performance.
NEW JOURNAL OF CHEMISTRY
(2022)
Article
Chemistry, Physical
Pooja S. Singh, Purav M. Badani, Rajesh M. Kamble
Summary: This study designed and synthesized carbazole-based dyes, characterized by spectroscopic methods to demonstrate the D-A assembly properties. The dyes exhibited blue-yellow emission and aggregation-induced emission in solution state, showing potential for applications in optoelectronic devices.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
(2021)
Article
Chemistry, Applied
Haifa Wu, Yu Zhang, Min Zhao, Xin Jin, Haitao Zhou, Yanqin Miao, Yan Huang, Jinhai Huang, Hua Wang, Jianhua Su
Summary: Two new bipolar host materials with excellent thermal stability and appropriate triplet energy levels were synthesized, and they were used to fabricate green PhOLEDs with good performance and extremely small efficiency rolloff.
Article
Chemistry, Applied
Hongyan Yang, Yanmei Li, Yuling Zhao, Shupei Yu, Hailin Ma, Long Qian, Ruidong Wang, Tianzhi Yu, Wenming Su
Summary: Four new indolo [3,2-b]carbazole derivatives with imidazole-derived moieties were successfully synthesized for highly efficient blue light-emitting devices. These hybrid compounds exhibited strong blue emissions in solutions and showed promising electroluminescence performance.
Article
Materials Science, Multidisciplinary
Jingwen Xu, Hao Liu, Jinshi Li, Zujin Zhao, Ben Zhong Tang
Summary: This study designed and synthesized four bipolar molecules with twisted donor-acceptor structures, demonstrating good luminescent properties and improving the efficiency and stability of deep-blue emissions in OLEDs.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Biochemical Research Methods
Nguyen Van Trang, Nguyen Minh Tam, Tran Ngoc Dung, Minh Tho Nguyen
Summary: A series of host molecules modified by adding nitrogen-containing group have been designed for phosphorescent organic light-emitting diode devices, showing potential as blue phosphorescent materials.
JOURNAL OF MOLECULAR GRAPHICS & MODELLING
(2021)
Article
Materials Science, Multidisciplinary
Dong Jun Kim, Sunhee Lee, Yong Hui Lee, Hyungkeun Jang, Kwang-Hyun Ahn, Won-Sik Han
Summary: Effective host materials play a crucial role in enhancing the performance of phosphorescent organic light-emitting diodes. In this study, a series of triazine-dibenzofuran-based n-type host materials were synthesized, with the position of dibenzofuran substitution found to significantly impact the chemical structure and properties. Among the developed materials, the green PhOLEDs utilizing DBT4/BPCz as a mixed host exhibited the best EL performance, showcasing high current efficiency, external quantum efficiency, power efficiency, and a device lifetime of 180 hours at 10,000 nits.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Ayato Arai, Hisahiro Sasabe, Kohei Nakao, Yuki Masuda, Junji Kido
Summary: In this study, by designing and developing benzothienocarbazole-based host materials, the pi conjugation of the carbazole unit was expanded to enhance OLED lifetime. The new material m1BTCBP demonstrated higher performance compared to mCBP, with an operational luminescence half-life of 300 hours.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Pengfei Yu, Yin Xiao
Summary: In this study, four bipolar blue-emitting materials were designed and synthesized, with carbazole, imidazole, and biphenyl as donor, acceptor, and p bridge, respectively. The incorporation of twisted phenylimidazole acceptor and appropriate substituents on the carbazole donor led to the successful development of a high-performance deep-blue OLED.
Editorial Material
Chemistry, Multidisciplinary
Jean-Luc Bredas, John R. Reynolds
SCIENCE CHINA-CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Chen Lu, Eunkyung Cho, Zhiyuan Cui, Yuhang Gao, Wenjuan Cao, Jean-Luc Bredas, Veaceslav Coropceanu, Feng Li
Summary: In contrast to closed-shell luminescent molecules, organic luminescent radicals have both spin doublet electronic states, resulting in spin-allowed radiative transitions. The efficiency and stability of donor-acceptor (D-A center dot) type luminescent radicals, which have a donor group covalently attached to an electron-withdrawing radical core, remain challenging to define. Experimental and theoretical results suggest that the luminescence efficiency and stability of the radicals are determined by the degree of conjugation and the number of imine nitrogen atoms in the substituents, with higher conjugation and lower number of imine nitrogen atoms leading to higher efficiency and stability.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Alexander K. Oanta, Kelsey A. Collins, Austin M. Evans, Saied Md Pratik, Lyndon A. Hall, Michael J. Strauss, Seth R. Marder, Deanna M. D'Alessandro, Tijana Rajh, Danna E. Freedman, Hong Li, Jean-Luc Bredas, Lei Sun, William R. Dichtel
Summary: This study introduces a method of embedding electronic spin qubits into two-dimensional polymers and analyzes the spin relaxation times at different spin densities and temperatures. The results show that lower spin densities lead to longer spin relaxation times, while higher spin densities decrease the spin relaxation times. The study demonstrates that dispersing electronic spin qubits within layered 2DPs enables chemical control of their inter-qubit interactions and spin decoherence times.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Subhajit Bhunia, Armando Pena-Duarte, Huifang Li, Hong Li, Mohamed Fathi Sanad, Pranay Saha, Matthew A. . Addicoat, Kotaro Sasaki, T. Amanda Strom, Miguel Jose Yacaman, Carlos R. . Cabrera, Ram Seshadri, Santanu Bhattacharya, Jean-Luc Bredas, Luis Echegoyen
Summary: Designing N-coordinated porous single-atom catalysts (SACs) is a promising approach for enhanced energy conversion. This study reports two efficient SAC systems, Co@rhm-PorBTD and Co@sql-PorBTD, based on Co(II)-porphyrin/ [2,1,3]-benzothiadiazole (BTD) covalent organic frameworks (COFs), for O2 electrocatalysis. Experimental results show that these COFs outperform commercial Pt/C by a large margin. The design and electrochemical performance of these COFs offer a pyrolysis-free bottom-up approach that avoids creating random atomic sites or unpredictable structural features.
Article
Chemistry, Multidisciplinary
Zachery A. Enderson, Harshavardhan Murali, Raghunath R. Dasari, Qingqing Dai, Hong Li, Timothy C. Parker, Jean-Luc Bredas, Seth R. Marder, Phillip N. First
Summary: Compared to conventional wet-chemical synthesis techniques, on-surface synthesis of organic networks in ultrahigh vacuum has fewer control parameters. The deposition rate and substrate temperature are the only adjustable synthesis variables. The creation and control of reducing conditions in the vacuum environment without dedicated sources can significantly influence the Ullmann-like on-surface reaction used for synthesizing 2D COFs. The manipulation of monomer and hydrogen fluxes can produce large self-assembled islands of interest, and the on-surface synthesis of oligomers avoids potential challenges with protracted wet-chemical synthesis and multiple deposition sources.
Article
Chemistry, Physical
Julia T. Kohn, Hong Li, Austin M. Evans, Jean-Luc Bredas, Stefan Grimme
Summary: 2D covalent organic frameworks (COFs) possess desirable mechanical and optoelectronic properties, but experimental structure determination remains challenging due to inseparable isomers and limited computational models. In this study, we go beyond the conventional description of COF building blocks and investigate the impact of different stacking and structural motifs on electronic properties. Using the SQM GFN-xTB method, we analyze the structural, energetic, electronic, and spectroscopic results of an imine-linked COF and compare them to experimental findings.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Physical
Dominique Lungwitz, Syed Joy, Ahmed E. Mansour, Andreas Opitz, Chamikara Karunasena, Hong Li, Naitik A. Panjwani, Karttikay Moudgil, Kan Tang, Jan Behrends, Stephen Barlow, Seth R. Marder, Jean-Luc Bredas, Kenneth Graham, Norbert Koch, Antoine Kahn
Summary: Evidence is provided by n-doping the polymer P(NDI2OD-T-2) with [RhCp*Cp](2), [N-DMBI](2), and cesium, and studying changes in the electronic structure using ultraviolet photoelectron and low-energy inverse photoemission spectroscopies (UPS, LEIPES). The UPS data shows an additional density of states (DOS) in the former empty polymer gap, while the LEIPES data shows an additional DOS above the conduction band edge. These DOS are assigned to the singly occupied and unoccupied sublevels, allowing determination of a U value of approximately 1eV.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Jianhua Bao, Kaitlyn P. P. Martin, Eunkyung Cho, Kyung-Seok Kang, Richard S. S. Glass, Veaceslav Coropceanu, Jean-Luc Bredas, Wallace O'Neil Parker, Jon T. T. Njardarson, Jeffrey Pyun
Summary: Organosulfur polymers derived from elemental sulfur via the inverse vulcanization process are a new and important class of macromolecules. However, the mechanism of inverse vulcanization and structural characterization of high-sulfur-content copolymers remain challenging. In this study, comprehensive structural characterizations were performed on poly-(S-r-DIB), revealing the incorrect assumptions about its repeating units and the significantly more complex polymerization mechanism.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Optics
Li Wan, Rui Zhang, Eunkyung Cho, Hongxiang Li, Veaceslav Coropceanu, Jean-Luc Bredas, Feng Gao
Summary: We propose a widely applicable strategy to fill the spectral gap of circularly polarized light (CPL) detection in the near-infrared (NIR) region by directly inducing chiroptical activity in planar non-fullerene acceptors. This strategy is found to be effective in a wide series of state-of-the-art non-fullerene acceptor families, including ITIC5, o-IDTBR6, and Y6 analogues.
Article
Materials Science, Multidisciplinary
Eunkyung Cho, Saied Md Pratik, Jeffrey Pyun, Veaceslav Coropceanu, Jean-Luc Bredas
Summary: Infrared (IR) thermal imaging is gaining attention for its wide range of applications. Due to the limitations of inorganic materials used for IR imaging, there is a push towards developing organic imaging materials. This study computationally assessed the suitability of pi-conjugated carbon-based materials for long-wave (LW) and mid-wave (MW) IR imaging applications. The results show that fullerenes, graphenes, and double-walled carbon nanotubes are transparent in both LWIR and MWIR regions.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Chemistry, Physical
Xiaojuan Ni, Hong Li, Jean-Luc Bredas
Summary: Theoretical investigations on poly(benzodifurandione) (PBDF) reveal its high electrical conductivity and unexpected solubility upon reduction (n-doping), with protons acting as counterions. The formation of polarons and bipolarons in n-doped PBDF and the electronic and magnetic properties of periodic 1D chains are elucidated.
CHEMISTRY OF MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Eunkyung Cho, Veaceslav Coropceanu, Jean-Luc Bredas
Summary: Density functional theory (DFT) calculations reveal that there are no significant differences between the hole and electron transport properties in C60 and C70 and their derivatives. The reorganization energy for hole transport in C70 is slightly lower than for electron transport, and this difference is even larger in functionalized C70 systems. The results suggest that hole mobilities in C70 and its derivatives could be comparable or even larger than the corresponding electron mobilities. Chemical modifications could be exploited to decrease the ionization potential energies of C60 and C70 and facilitate hole injection.
ORGANIC ELECTRONICS
(2023)
Article
Chemistry, Multidisciplinary
Zhanxiang Chen, Manli Huang, Cheng Zhong, Shaolong Gong, Veaceslav Coropceanu, Jean-Luc Bredas, Chuluo Yang
Summary: It is a challenge to achieve high luminescence dissymmetry factor (g) in circularly polarized luminescence (CPL) materials. In this study, we investigated the role of molecular structure on CPL and found that delocalized transition density and optimized chromophore twisting are crucial for obtaining large g-factors. These findings provide molecular-level insights into CPL of organic emitters and have potential applications in the design of chiroptical materials and systems with strong CPL effects.
Article
Materials Science, Multidisciplinary
Xiaojuan Ni, Sadisha Nanayakkara, Hong Li, Jean-Luc Bredas
Summary: Low-dimensional hybrid organic-inorganic perovskites with high compositional and structural flexibilities have attracted significant attention for their distinct optoelectronic properties, such as in light-emitting and photovoltaic applications. In this study, we used density functional theory (DFT) to investigate the electronic and optical properties of two one-dimensional hybrid perovskites containing cyanine or Victoria blue B (VBB) dye cations. Our analyses demonstrated that the highest occupied molecular orbitals of the dye cations align closely with the band edges of the inorganic component, but wavefunction delocalization only occurs in the cyanine-perovskite system with weak electronic couplings between the organic and inorganic components. Time-dependent DFT calculations on finite cluster models revealed a small degree of charge-transfer contributions to the low-lying excited states in the cyanine-perovskite system, resulting in broadening of the lowest absorption band.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Chemistry, Physical
Anubhab Chakraborty, Percy Zahl, Qingqing Dai, Hong Li, Torsten Fritz, Paul Simon, Jean-Luc Bredas, Oliver L. A. Monti
Summary: This study introduces a new concept of using frontier orbital degeneracy to tailor the magnetic state of molecular adsorbates. It is demonstrated for the case of the organic semiconductor HATCN on Ag(111). The study reveals the existence of two different molecular magnetic states for HATCN on Ag(111), which can be determined by scanning tunneling microscopy/spectroscopy measurements.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)