Chemistry of Materials
DOI: 10.1021/acs.chemmater.9b04464
Shared posts
03 Jan 01:02
[ASAP] Origin of the High Donor–Acceptor Composition Tolerance in Device Performance and Mechanical Robustness of All-Polymer Solar Cells
by Jin-Woo Lee†?, Boo Soo Ma‡?, Joonhyeong Choi†, Junbok Lee†, Seungjin Lee†, Kin Liao§, Wonho Lee*?, Taek-Soo Kim*‡, and Bumjoon J. Kim*†
02 Jan 13:38
Environmental Control of Triplet Emission in Donor–Bridge–Acceptor Organometallics
by Jiale Feng,
Lupeng Yang,
Alexander S. Romanov,
Jirawit Ratanapreechachai,
Antti‐Pekka M. Reponen,
Saul T. E. Jones,
Mikko Linnolahti,
Timothy J. H. Hele,
Anna Köhler,
Heinz Bässler,
Manfred Bochmann,
Dan Credgington
How to gently tune emission from green to blue? The luminescence of organic emitters can be blueshifted via triplet diffusion and electrostatic interactions with surrounding molecules without chemical modifications while preserving excellent molecular and photophysical properties.
Abstract
Carbene‐metal‐amides (CMAs) are a promising family of donor–bridge–acceptor molecular charge‐transfer (CT) emitters for organic light‐emitting diodes. A universal approach is demonstrated to tune the energy of their CT emission. A blueshift of up to 210 meV is achievable in solid state via dilution in a polar host matrix. The origin of this shift has two components: constraint of thermally‐activated triplet diffusion, and electrostatic interactions between guest and polar host. This allows the emission of mid‐green CMA archetypes to be tuned to sky blue without chemical modifications. Monte‐Carlo simulations based on a Marcus‐type transfer integral successfully reproduce the concentration‐ and temperature‐dependent triplet diffusion process, revealing a substantial shift in the ensemble density of states in polar hosts. In gold‐bridged CMAs, this shift does not lead to a significant change in luminescence lifetime, thermal activation energy, reorganization energy, or intersystem crossing rate. These discoveries offer new insight into coupling between the singlet and triplet manifolds in CMA materials, revealing a dominant interaction between states of CT character. The same approach is employed using materials which have been chemically modified to alter the energy of their CT state directly, shifting the emission of sky‐blue chromophores into the practical blue range.
以昇陳 likes this
02 Jan 03:11
[ASAP] Harnessing a New Co-Host System and Low Concentration of New TADF Emitters Equipped with Trifluoromethyl- and Cyano-Substituted Benzene as Core for High-Efficiency Blue OLEDs
by Chih-Lun Yi†, Chang-Lun Ko‡, Tzu-Chin Yeh†, Chih-Yang Chen‡, Yi-Sheng Chen†, Deng-Gao Chen†, Pi-Tai Chou†, Wen-Yi Hung*‡§, and Ken-Tsung Wong*†?
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b18272
Rong-Huei Yi, Ye Shaofeng and one other like this
02 Jan 03:08
[ASAP] Room-Temperature Dual Fluorescence of a Locked Green Fluorescent Protein Chromophore Analogue
by Soumit Chatterjee§, Ketan Ahire, and Peter Karuso*
Journal of the American Chemical Society
DOI: 10.1021/jacs.9b05096
31 Dec 07:02
Charge‐Transfer Exciton Manipulation Based on Hydrogen Bond for Efficient White Thermally Activated Delayed Fluorescence
by Jianan Sun,
Jing Zhang,
Qianqian Liang,
Ying Wei,
Chunbo Duan,
Chunmiao Han,
Hui Xu
White organic light‐emitting diodes (WOLED) based on full thermally activated delayed fluorescence (TADF) systems are optmized by charge‐transfer exciton manipulation for optimal exciton allocation. Through introducing steric hindrance–modulated hydrogen bond networks, exciton delocalization in the blue matrix is optimized to balance the blue and yellow emissions for state‐of‐the‐art external quantum efficiency beyond 20%, and excellent white light stability.
Abstract
Despite the success of thermally activated delayed fluorescence (TADF) emitters in monochromatic organic light‐emitting diodes (OLED), only few efficient full‐TADF white OLEDs (WOLED) are reported because of the challenge in rational exciton allocation between blue and other color emitters. Herein, it is demonstrated that the appropriate exciton delocalization in blue TADF matrixes can simultaneously support the sufficient blue emission and the energy loss–free charge and exciton transfer to yellow TADF emitters. Through introducing steric hindrance–modulated intermolecular hydrogen bond networks, a fluorinated carbazole‐phosphine oxide hybrid realizes the balance of exciton localization and delocalization, giving rise to state‐of‐the‐art external quantum efficiency beyond 20% from its simple trilayer full‐TADF WOLEDs, accompanied by excellent spectral stability. The correlation between the efficiencies of the blue TADF matrixes and their intermolecular interactions reveals that the exciton delocalization is crucial for the exciton allocation optimization in multicomponent emission systems.
30 Dec 12:28
Light Detection in Open‐Circuit Voltage Mode of Organic Photodetectors
by Marcin Kielar,
Tasnuva Hamid,
Martin Wiemer,
François Windels,
Lionel Hirsch,
Pankaj Sah,
Ajay K. Pandey
The open‐circuit voltage regime of standard organic photodetector (OPD) operation is revealed as a powerful method for detecting low light signals. In photovoltage mode, light sensitivity across nine orders of magnitude is demonstrated. This opens up new perspectives for resolving low light signals and provides simplified design rules for OPDs.
Abstract
Organic photodetectors (OPDs) are promising candidates for next‐generation light sensors as they combine unique material properties with high‐level performance in converting photons into electrical signals. However, low‐level light detection with OPD is often limited by device dark current. Here, the open‐circuit voltage (Voc ) regime of OPDs is shown to be efficient for detecting low light signals (<100 µW cm−2). It is established that the light‐dependence of Voc exhibits two distinct regimes as function of irradiance: linear and logarithmic. Whereas the observed logarithmic regime is well understood in organic photovoltaic cells (OPVs), it is shown experimentally and theoretically that the linear regime is due to the non‐infinite shunt resistance of the OPD device. Overall, OPDs composed of rubrene and fullerene show photovoltage light sensitivity across nine orders of magnitude with a detection limit as low as 400 pW cm−2. A photovoltage responsivity of 1.75 V m2 W−1 demonstrates highly efficient performance without the necessity to supress high dark current. This approach opens up new possibilities for resolving low light signals and provides simplified design rules for OPDs.
以昇陳 likes this
30 Dec 12:27
Revealing the Interplay between Charge Transport, Luminescence Efficiency, and Morphology in Organic Light‐Emitting Diode Blends
by Mile Gao,
Thomas Lee,
Paul L. Burn,
Alan E. Mark,
Almantas Pivrikas,
Paul E. Shaw
Film morphologies created using atomistic nonequilibrium molecular dynamics simulations mimicking the co‐evaporation of Ir(ppy)3 and TCTA provide insight into the experimentally‐measured hole mobility and photophysical properties. Clustering of the Ir(ppy)3 molecules at different concentrations in the blend is consistent with the measured hole mobility, and partial overlap of the Ir(ppy)3 ligands is required for luminescence quenching to occur.
Abstract
Phosphorescent emissive materials in organic light‐emitting diodes (OLEDs) manufactured using evaporation are usually blended with host materials at a concentration of 3–15 wt% to avoid concentration quenching of the luminescence. Here, experimental measurements of hole mobility and photoluminescence are related to the atomic level morphology of films created using atomistic nonequilibrium molecular dynamics simulations mimicking the evaporation process with similar guest concentrations as those used in operational test devices. For blends of fac‐tris[2‐phenylpyridinato‐C2,N]iridium(III) [Ir(ppy)3] in tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA), it is found that clustering of the Ir(ppy)3 (surface of the molecules within ≈0.4 nm) in the simulated films is directly relatable to the experimentally‐measured hole mobility. Films containing 1–10 wt% of Ir(ppy)3 in TCTA have a mobility of up to two orders of magnitude lower (≈10−6 cm2 V−1 s−1) than the neat TCTA film, which is consistent with the Ir(ppy)3 molecules acting as hole traps due to their smaller ionization potential. Comparison of the simulated film morphologies with the measured photoluminescence properties shows that for luminescence quenching to occur, the Ir(ppy)3 molecules have to have their ligands partially overlapping. Thus, the results show that the effect of guest interactions on charge transport and luminescence are markedly different for OLED light‐emitting layers.
28 Dec 15:54
Tailoring and Modifying an Organic Electron Acceptor toward the Cathode Interlayer for Highly Efficient Organic Solar Cells
by Qing Liao,
Qian Kang,
Yi Yang,
Cunbin An,
Bowei Xu,
Jianhui Hou
Novel cathode interlayers (CILs) are developed by tailoring an organic electron acceptor, viz. ITIC. A high efficiency of 16.6% is achieved in an organic solar cell with S‐3 as the CIL. It is demonstrated that the difference of electrostatic surface potential between the CIL molecule and the polymer donor can promote exciton dissociation, contributing to additional charge generation.
Abstract
With the rapid advance of organic photovoltaic materials, the energy level structure, active layer morphology, and fabrication procedure of organic solar cells (OSCs) are changed significantly. Thus, the photoelectronic properties of many traditional electrode interlayers have become unsuitable for modifying new active layers; this limits the further enhancement in OSC efficiencies. Herein, a new design strategy of tailoring the end‐capping unit, ITIC, to develop a cathode interlayer (CIL) material for achieving high power conversion efficiency (PCE) in OSCs is demonstrated. The excellent electron accepting capacity, suitable energy level, and good film‐forming ability endow the S‐3 molecule with an outstanding electron extraction property. A device with S‐3 shows a PCE of 16.6%, which is among the top values in the field of OSCs. More importantly, it is demonstrated that the electrostatic potential difference between the CIL molecule and the polymer donor plays a crucial role in promoting exciton dissociation at the CIL/active layer interface, contributing to additional charge generation; this is crucial for enhancement of the current density. The results of this work not only develop a new design strategy for high‐performance CIL, but also demonstrate a reliable approach of density functional theory (DFT) calculation to predict the effect of the CIL chemical structure on exciton dissociation in OSCs.
27 Dec 11:58
[ASAP] Rational Design of Low Band Gap Polymers for Efficient Solar Cells with High Open-Circuit Voltage: The Profound Effect of Me and Cl Substituents with a Similar van Der Waals Radius
by Xiao Kang†‡?, Di Zhou‡§?, Qian Wang‡, Dangqiang Zhu‡, Xichang Bao*‡?, Xiyue Yuan‡, Fushuai Liu‡, Yonghai Li‡, Shanlin Qiao*†, and Renqiang Yang*‡?
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b18278
以昇陳, JIANG ZHI XUAN and 4 others like this
27 Dec 11:55
[ASAP] Suppression of Interfacial Disorders in Solution-Processed Metal Oxide Thin-Film Transistors by Mg Doping
by Jae Sang Heo†‡?, Seong-Pil Jeon†?, Insoo Kim‡, Woobin Lee§, Yong-Hoon Kim*§, and Sung Kyu Park*†
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b17642
以昇陳 likes this
27 Dec 11:54
[ASAP] Aggregation-Induced Emission Active Donor–Acceptor Fluorophore as a Dual Sensor for Volatile Acids and Aromatic Amines
by Kingshuk Debsharma, Jampani Santhi, Beeraiah Baire*, and Edamana Prasad*
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b17988
27 Dec 11:49
[ASAP] Lead Oxalate-Induced Nucleation Retardation for High-Performance Indoor and Outdoor Perovskite Photovoltaics
by Chong Dong†, Meng Li†, Yue Zhang†, Kai-Li Wang†, Shuai Yuan†, Femi Igbari†, Yingguo Yang‡, Xingyu Gao‡, Zhao-Kui Wang*†, and Liang-Sheng Liao*†
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b18230
xiaodaibudai, 以昇陳 and one other like this
27 Dec 11:48
[ASAP] Design of Blue Thermally Activated Delayed Fluorescent Emitter with Efficient Exciton Gathering Property for High-Performance Fully Solution-Processed Hybrid White OLEDs
by Xinxin Ban†, Yan Liu†, Jie Pan†, Feng Chen†, Aiyun Zhu†, Wei Jiang*‡, Yueming Sun‡, and Yajie Dong§
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b20903
以昇陳, Qing Zhang likes this
26 Dec 06:05
Dopant‐Free, Donor–Acceptor‐Type Polymeric Hole‐Transporting Materials for the Perovskite Solar Cells with Power Conversion Efficiencies over 20%
by Guofeng You,
Qixin Zhuang,
Lijun Wang,
Xinyu Lin,
Ding Zou,
Zhenghuan Lin,
Hongyu Zhen,
Wenliu Zhuang,
Qidan Ling
Two electron donor (D)–electron acceptor (A)‐type polymers PBDTT and PBTTT are developed as hole‐transporting materials for perovskite solar cells (PVSCs). Both polymers endow the PVSCs promising device performance. A power conversion efficiency of 20.28% is achieved from the devices with dopant‐free PBDTT. High device stability can be expected by employing these compact and hydrophobic polymeric hole‐transporting layers.
Abstract
The rich molecular design of electron donor (D)–acceptor (A) polymers offers many valuable clues to obtain high‐efficiency hole‐transporting materials (HTMs) for use in perovskite solar cells (PVSCs). The fused aromatic or heteroaromatic units can increase the conjugation of the polymer backbone to facilitate electron delocalization, which increases the rigidity of adjacent units to prevent rotational disorder and lower the reorganization energy, leading to improved carrier mobility and optimized film morphology. In this work, fused‐ring ladder‐type indacenodithiophene and indacenodithieno[3,2‐b]thiophene are used as D units, benzodithiophene‐4,8‐dione as the A unit, and thienothiophene as a π‐bridge to form the D–A polymers PBDTT and PBTTT, respectively. Both polymers exhibit favorable properties as HTMs including suitable energy levels, high hole mobility, and excellent film quality. Both dopant‐free HTMs endow n‐i‐p PVSCs with promising performance and stability. A maximum power conversion efficiency of 20.28% is achieved for PBDTT‐based devices, which is among the highest values reported to date.
以昇陳 likes this
25 Dec 03:56
Revealing the Interplay between Charge Transport, Luminescence Efficiency, and Morphology in Organic Light‐Emitting Diode Blends
by Mile Gao,
Thomas Lee,
Paul L. Burn,
Alan E. Mark,
Almantas Pivrikas,
Paul E. Shaw
Film morphologies created using atomistic nonequilibrium molecular dynamics simulations mimicking the co‐evaporation of Ir(ppy)3 and TCTA provide insight into the experimentally‐measured hole mobility and photophysical properties. Clustering of the Ir(ppy)3 molecules at different concentrations in the blend is consistent with the measured hole mobility, and partial overlap of the Ir(ppy)3 ligands is required for luminescence quenching to occur.
Abstract
Phosphorescent emissive materials in organic light‐emitting diodes (OLEDs) manufactured using evaporation are usually blended with host materials at a concentration of 3–15 wt% to avoid concentration quenching of the luminescence. Here, experimental measurements of hole mobility and photoluminescence are related to the atomic level morphology of films created using atomistic nonequilibrium molecular dynamics simulations mimicking the evaporation process with similar guest concentrations as those used in operational test devices. For blends of fac‐tris[2‐phenylpyridinato‐C2,N]iridium(III) [Ir(ppy)3] in tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA), it is found that clustering of the Ir(ppy)3 (surface of the molecules within ≈0.4 nm) in the simulated films is directly relatable to the experimentally‐measured hole mobility. Films containing 1–10 wt% of Ir(ppy)3 in TCTA have a mobility of up to two orders of magnitude lower (≈10−6 cm2 V−1 s−1) than the neat TCTA film, which is consistent with the Ir(ppy)3 molecules acting as hole traps due to their smaller ionization potential. Comparison of the simulated film morphologies with the measured photoluminescence properties shows that for luminescence quenching to occur, the Ir(ppy)3 molecules have to have their ligands partially overlapping. Thus, the results show that the effect of guest interactions on charge transport and luminescence are markedly different for OLED light‐emitting layers.
以昇陳, Qing Zhang likes this
25 Dec 03:55
[ASAP] Coordination-Induced Thermally Activated Delayed Fluorescence: From Non-TADF Donor–Acceptor-Type Ligand to TADF-Active Ag-Based Complexes
by Ji-Hui Jia†§, Dong Liang†?, Rongmin Yu†, Xu-Lin Chen†‡, Lingyi Meng†‡, Jian-Fei Chang†§, Jian-Zhen Liao†, Mingxue Yang†§, Xiao-Ning Li†, and Can-Zhong Lu*†‡
Chemistry of Materials
DOI: 10.1021/acs.chemmater.9b04585
Ye Shaofeng, 以昇陳 likes this
25 Dec 03:03
[ASAP] Open-Shell Effects on Optoelectronic Properties: Antiambipolar Charge Transport and Anti-Kasha Doublet Emission from a N-Substituted Bisphenalenyl
by Muhammad Imran†, Caleb M. Wehrmann†, and Mark S. Chen*
Journal of the American Chemical Society
DOI: 10.1021/jacs.9b10677
jingjiniao, Qing Zhang and one other like this
24 Dec 13:06
Constitutional Isomerization Enables Bright NIR‐II AIEgen for Brain‐Inflammation Imaging
by Shunjie Liu,
Chao Chen,
Yuanyuan Li,
Haoke Zhang,
Junkai Liu,
Ran Wang,
Sherman T. H. Wong,
Jacky W. Y. Lam,
Dan Ding,
Ben Zhong Tang
On the basis of the molecular design philosophy for aggregation‐induced emission (AIE), here, a constitutional isomerization strategy involving the combination of backbone distortion and rotor twisting is demonstrated. The resultant AIEgen displays a high quantum yield of 11% with an emission peak of 1030 nm. Further, neutrophils are creatively used as carriers to detect brain inflammation with a high signal‐to‐background ratio of 30.6.
Abstract
The shortage of high quantum yield (QY) organic fluorophores in the second near‐infrared window (NIR‐II) has become a bottleneck in bioimaging field. Now, a simple strategy is proposed to address this: constitutional isomerization on the basis of the molecular design philosophy of aggregation‐induced emission. With the combination of backbone distortion and rotor twisting, the resultant NIR‐II fluorophore 2TT‐oC6B displays an emission peak at 1030 nm and a QY of 11% in nanoparticles, one of the highest reported so far. Control molecules confirm that the distorted backbone and twisted rotors play equally important roles in determining the fluorescence properties of the NIR‐II fluorophores. To allow for the targeting ability to reach deeply located diseases, neutrophils (NEs) are used to penetrate the brain tissues and accumulate in the inflammation site. Herein, it is shown that NEs carrying 2TT‐oC6B nanoparticles can penetrate the blood‐brain‐barrier and visualize the deeply located inflammation through an intact scalp and skull. Notably, the bright 2TT‐oC6B contributes to a significantly enhanced signal‐to‐background ratio of 30.6 in the brain inflammation site.
以昇陳 likes this
24 Dec 13:05
Light Detection in Open‐Circuit Voltage Mode of Organic Photodetectors
by Marcin Kielar,
Tasnuva Hamid,
Martin Wiemer,
François Windels,
Lionel Hirsch,
Pankaj Sah,
Ajay K. Pandey
The open‐circuit voltage regime of standard organic photodetector (OPD) operation is revealed as a powerful method for detecting low light signals. In photovoltage mode, light sensitivity across nine orders of magnitude is demonstrated. This opens up new perspectives for resolving low light signals and provides simplified design rules for OPDs.
Abstract
Organic photodetectors (OPDs) are promising candidates for next‐generation light sensors as they combine unique material properties with high‐level performance in converting photons into electrical signals. However, low‐level light detection with OPD is often limited by device dark current. Here, the open‐circuit voltage (Voc ) regime of OPDs is shown to be efficient for detecting low light signals (<100 µW cm−2). It is established that the light‐dependence of Voc exhibits two distinct regimes as function of irradiance: linear and logarithmic. Whereas the observed logarithmic regime is well understood in organic photovoltaic cells (OPVs), it is shown experimentally and theoretically that the linear regime is due to the non‐infinite shunt resistance of the OPD device. Overall, OPDs composed of rubrene and fullerene show photovoltage light sensitivity across nine orders of magnitude with a detection limit as low as 400 pW cm−2. A photovoltage responsivity of 1.75 V m2 W−1 demonstrates highly efficient performance without the necessity to supress high dark current. This approach opens up new possibilities for resolving low light signals and provides simplified design rules for OPDs.
Ma Lanchao, 以昇陳 likes this
24 Dec 13:05
Excited State Dynamics of a Self‐Doped Conjugated Polyelectrolyte
by Demetra Tsokkou,
Lisa Peterhans,
David Xi Cao,
Cheng‐Kang Mai,
Guillermo C. Bazan,
Thuc‐Quyen Nguyen,
Natalie Banerji
The ultrafast photophysical properties of a self‐doped conjugated polyelectrolyte are experimentally studied to shed light on optoelectronic properties of doping‐induced polarons and their interactions with their surroundings. Here, important evidence that polarons not only affect their environment via Coulomb effects but also strongly couple electronically to nearby neutral sites is provided.
Abstract
The growing number of applications of doped organic semiconductors drives the development of highly conductive and stable materials. Lack of understanding about the formation and properties of mobile charges limits the ability to improve material design. Thus the largely unexplored photophysics of doped systems are addressed here to gain insights about the characteristics of doping‐induced polarons and their interactions with their surroundings. The study of the ultrafast optical processes in a self‐doped conjugated polyelectrolyte reveals that polarons not only affect their environment via Coulomb effects but also strongly couple electronically to nearby neutral sites. This is unambiguously demonstrated by the simultaneous depletion of both the neutral and polaronic transitions, as well as by correlated excited state dynamics, when either transition is targeted during ultrafast experiments. The results contrast with the conventional picture of localized intragap polaron states but agree with revised models for the optical transitions in doped organic materials, which predict a common ground level for polarons and neighboring neutral sites. Such delocalization of polarons into the frontier transport levels of their surroundings could enhance the electronic connectivity between doped and undoped sites, contributing to the formation of conductive charges.
以昇陳, wanghonglanzhou likes this
24 Dec 06:02
Record High External Quantum Efficiency of 19.2% Achieved in Light‐Emitting Diodes of Colloidal Quantum Wells Enabled by Hot‐Injection Shell Growth
by Baiquan Liu,
Yemliha Altintas,
Lin Wang,
Sushant Shendre,
Manoj Sharma,
Handong Sun,
Evren Mutlugun,
Hilmi Volkan Demir
Light‐emitting diodes based on colloidal quantum wells (CQWs) exhibit an external quantum efficiency close to the theoretical maximum of 20%. The core/hot‐injection shell CQWs show a near‐unity photoluminescence quantum yield, retaining 87% in film even after five times cleaning. A luminance of 23 490 cd m−2, along with an extremely stable color point of saturated red electroluminescence is achieved.
Abstract
Colloidal quantum wells (CQWs) are regarded as a highly promising class of optoelectronic materials, thanks to their unique excitonic characteristics of high extinction coefficients and ultranarrow emission bandwidths. Although the exploration of CQWs in light‐emitting diodes (LEDs) is impressive, the performance of CQW‐LEDs lags far behind other types of soft‐material LEDs (e.g., organic LEDs, colloidal‐quantum‐dot LEDs, and perovskite LEDs). Herein, high‐efficiency CQW‐LEDs reaching close to the theoretical limit are reported. A key factor for this high performance is the exploitation of hot‐injection shell (HIS) growth of CQWs, which enables a near‐unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films, and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape‐, composition‐, and device‐engineering, the CQW‐LEDs using CdSe/Cd0.25Zn0.75S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23 490 cd m−2, extremely saturated red color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.715, 0.283), and stable emission are obtained. The findings indicate that HIS‐grown CQWs enable high‐performance solution‐processed LEDs, which may pave the path for future CQW‐based display and lighting technologies.
jingjiniao, 以昇陳 and -1 others like this
23 Dec 02:26
[ASAP] Effects of Monofluorinated Positions at the End-Capping Groups on the Performances of Twisted Non-Fullerene Acceptor-Based Polymer Solar Cells
by Haimei Wu†?, Baofeng Zhao†?, Heng Zhao‡, Liuchang Wang§, Weiping Wang†, Zhiyuan Cong†, Jianqun Liu†, Wei Ma*‡, and Chao Gao*†
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b18301
JIANG ZHI XUAN, Fiona-moon and 3 others like this
23 Dec 02:25
[ASAP] Molecular Engineering of Thermally Activated Delayed Fluorescence Emitters with Aggregation-Induced Emission via Introducing Intramolecular Hydrogen-Bonding Interactions for Efficient Solution-Processed Nondoped OLEDs
by Fulong Ma, Guimin Zhao, Yu Zheng, Fangru He, Kamran Hasrat, and Zhengjian Qi*
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.9b17545
以昇陳 likes this
22 Dec 15:22
Photochemical Carbopyridylation of Alkenes Using N‐Alkenoxypyridinium Salts as Bifunctional Reagents
by Gangadhar Rao Mathi,
Yujin Jeong,
Yonghoon Moon,
Sungwoo Hong
On the double: Visible‐light‐induced carbopyridylation of alkenes has been achieved using N‐alkenoxypyridinium salts as both α‐carbonyl radical precursors and pyridine sources. Regioselective addition of an α‐carbonyl radical onto an olefin followed by pyridylation led to the introduction of two valuable chemical entities in an atom‐economical fashion to eventually provide synthetically useful γ‐pyridyl ketones.
Abstract
N‐Alkenoxypyridinium salts have been used as synthons for the umpolung reaction of enolates for the preparation of α‐functionalized carbonyl compounds. In contrast, we found that the photoreduction of N‐alkenoxypyridinium salts generates α‐carbonyl radicals after cleavage of the N−O bond, thereby allowing simultaneous incorporation of α‐keto and pyridyl groups across unactivated alkenes. In the process, the formed α‐carbonyl radicals engage unactivated alkenes to afford alkyl radical intermediates poised for subsequent addition to pyridinium salts, which ultimately affords a variety of γ‐pyridyl ketones under mild reaction conditions. This transformation is characterized by a broad substrate scope and good functional‐group compatibility, and the utility of this transformation was further demonstrated by the late‐stage functionalization of complex biorelevant molecules.
21 Dec 15:07
Indandione‐Terminated Quinoids: Facile Synthesis by Alkoxide‐Mediated Rearrangement Reaction and Semiconducting Properties
by Tian Du,
Ruiheng Gao,
Yunfeng Deng,
Cheng Wang,
Qian Zhou,
Yanhou Geng
Electronic building blocks: 1,3‐Indandione‐terminated quinoids with various termini and central cores were synthesized by an alkoxide‐mediated rearrangement reaction. Their properties can be regulated by tuning the central cores and the aryl termini. These compounds display unipolar n‐type semiconductor characteristics with electron mobilities of up to 0.38 cm2 V−1 s−1.
Abstract
A series of 1,3‐indandione‐terminated π‐conjugated quinoids were synthesized by alkoxide‐mediated rearrangement reaction of the respective alkene precursors, followed by air oxidation. This new protocol allows access to quinoidal compounds with variable termini and cores. The resulting quinoids all show LUMO levels below −4.0 eV and molar extinction coefficients above 105 L mol−1 cm−1. The optoelectronic properties of these compounds can be regulated by tuning the central cores as well as the aryl termini ascribed to the delocalized frontier molecular orbitals over the entire molecular skeleton involving aryl termini. n‐Channel organic thin‐film transistors with electron mobility of up to 0.38 cm2 V−1 s−1 were fabricated, showing the potential of this new class of quinoids as organic semiconductors.
20 Dec 16:25
[ASAP] Fine-Tuning Semiconducting Polymer Self-Aggregation and Crystallinity Enables Optimal Morphology and High-Performance Printed All-Polymer Solar Cells
by Yilei Wu†, Sebastian Schneider‡§, Christopher Walter†, Ashraful Haider Chowdhury?, Behzad Bahrami?, Hung-Chin Wu†, Qiquan Qiao?, Michael F. Toney*§, and Zhenan Bao*†
Journal of the American Chemical Society
DOI: 10.1021/jacs.9b10935
KunYang, Jabranejouha and 9 others like this
17 Dec 06:46
Accurate Determination of the Minimum HOMO Offset for Efficient Charge Generation using Organic Semiconducting Alloys
by Jianyun Zhang,
Wenrui Liu,
Guanqing Zhou,
Yuanping Yi,
Shengjie Xu,
Feng Liu,
Haiming Zhu,
Xiaozhang Zhu
Exciton dissociation into free charges is the most important optoelectronic process in organic solar cells, which is driven by the energy‐level offset of electron‐donor and ‐acceptor materials. With the continuously tunable HOMO level achieved by organic semiconducting alloys, the minimum HOMO offset of ≈40 meV is shown to be necessary to achieve the most efficient exciton dissociation and photovoltaic performance.
Abstract
Current research indicates that exciton dissociation into free charge carriers can be achieved in material combinations with the highest occupied molecular orbital (HOMO) offset lowered to 0 eV in non‐fullerene organic solar cells. However, the quantitative relationship between the HOMO offset and exciton dissociation has not been established because of the difficulty in achieving continuously tunable HOMO offsets. Here, the binary blends of PTQ10:ZITI‐S and PTQ10:ZITI‐N are combined to form the positive and negative HOMO offsets of 0.20 and −0.07 eV, respectively. While the PTQ10:ZITI‐S binary blend delivers a decent power conversion efficiency (PCE) of 10.69% with a short‐circuit current (J sc) of 16.94 mA cm−2, the PTQ10:ZITI‐N with the negative offset shows a much lower PCE of 7.06% mainly because of the low J sc of 12.03 mA cm−2. Because the tunable HOMO levels can be realized in organic semiconducting alloys based on ZITI‐N and ZITI‐S acceptors, the transformation of the HOMO energy offset from negative to positive values is achieved in the PTQ10:ZITIN:ZITI‐S ternary blends, delivering much‐improved PCEs up to 13.26% with a significant, 74% enhancement of J sc to 20.93 mA cm−2. With detailed investigations, the study reveals that the minimum HOMO offset of ≈40 meV is required to achieve the most‐efficient exciton dissociation and photovoltaic performance.
17 Dec 06:44
[ASAP] Designing High Performance Nonfullerene Electron Acceptors with Rylene Imides for Efficient Organic Photovoltaics
by Nagesh B. Kolhe†‡, Sarah M. West†‡, Duyen K. Tran†‡, Xiaomei Ding†, Daiki Kuzuhara§, Noriyuki Yoshimoto§, Tomoyuki Koganezawa?, and Samson A. Jenekhe*†
Chemistry of Materials
DOI: 10.1021/acs.chemmater.9b03329
15 Dec 09:56
Polymorph‐Dependent Thermally Activated Delayed Fluorescence Emitters: Understanding TADF from a Perspective of Aggregation State
by Kailu Zheng,
Fan Ni,
Zhanxiang Chen,
Cheng Zhong,
Chuluo Yang
Multifunctional organic emitters : An organic luminescent material exhibits multifarious properties of thermally activated fluorescence (TADF), aggregation‐induced emission (AIE), multi‐color mechanochromic luminescence (MCL), and polymorphism.
Abstract
Current research on thermally activated fluorescence (TADF) emitters is mainly based on the molecular levels, while the aggregation states of TADF emitters are to be explored deeply. Now two multifunctional emitters are reported with simultaneous TADF, aggregation induced emission (AIE), and multicolor mechanochromic luminescence (MCL) features. Both emitters also show polymorph‐dependent TADF emission. Crystal structure analysis reveals that the polymorphism is ascribed to the mutable conformations in different aggregation states. This work brings new insight to TADF emitters from a perspective of aggregation states.
Ye Shaofeng, YC Hu and 4 others like this
14 Dec 07:52
[ASAP] P-Chiral Phosphines Enabled by Palladium/Xiao-Phos-Catalyzed Asymmetric P–C Cross-Coupling of Secondary Phosphine Oxides and Aryl Bromides
by Qiang Dai†, Wenbo Li†, Zhiming Li§, and Junliang Zhang*†§
Journal of the American Chemical Society
DOI: 10.1021/jacs.9b11938