http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Whang, Dong Ryeol,You, Youngmin,Chae, Weon-Sik,Heo, Jeongyun,Kim, Sehoon,Park, Soo Young American Chemical Society 2012 Langmuir Vol.28 No.44
<P>In this study, we have demonstrated the reconstruction of encrypted information by employing photoluminescence spectra and lifetimes of a phosphorescent Ir(III) complex (IrHBT). IrHBT was constructed on the basis of a heteroleptic structure comprising a fluorescent N<SUP>∧</SUP>O ancillary ligand. From the viewpoint of information security, the transformation of the Ir(III) complex between phosphorescent and fluorescent states can be encoded with chemical/photoirradiation methods. Thin polymer films (poly(methylmethacrylate), PMMA) doped with IrHBT display long-lived emission typical of phosphorescence (λ<SUB>max</SUB> = 586 nm, τ<SUB>obs</SUB> = 2.90 μs). Meanwhile, exposure to HCl vapor switches the emission to fluorescence (λ<SUB>max</SUB> = 514 nm, τ<SUB>obs</SUB> = 1.53 ns) with drastic changes in both the photoluminescence color and lifetime. Security printing on paper impregnated with IrHBT or on a PMMA film containing IrHBT and photoacid generator (triphenylsulfonium triflate) enables the bimodal readout of photoluminescence color and lifetime.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2012/langd5.2012.28.issue-44/la3032013/production/images/medium/la-2012-032013_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la3032013'>ACS Electronic Supporting Info</A></P>
Whang, Dong Ryeol,Park, Soo Young Wiley-VCH 2015 ChemSusChem Vol.8 No.19
<P>Herein we report a Pt-II complex containing a 4,4-bis[4-(triphenylsilyl)phenyl]-2,2-bipyridine ligand as a molecular catalyst for water splitting. Systematic studies of the electrochemical and electronic properties of this catalyst, in comparison with two control complexes, reveal electron-reservoir characteristics upon two-electron reduction. A turnover number of 510000 was recorded by employing this complex as a water reduction catalyst in combination with a state-of-the-art photosensitizer and N,N-dimethylaniline as a sacrificial electron donor, which represents a large improvement over the control complexes that do not contain the tetraphenylsilyl ligand substitution.</P>
Yoon, Won Sik,Kim, Dong Won,Park, Jun-Mo,Cho, Illhun,Kwon, Oh Kyu,Whang, Dong Ryeol,Kim, Jin Hong,Park, Jung-Hwa,Park, Soo Young American Chemical Society 2016 Macromolecules Vol.49 No.22
<P>A novel electron-accepting bis-lactam building block, 3,7-dithiophen-2-yl-1,5-dialkyl-1,5-naphthyridine-2,6-dione (NTDT), and a conjugated polymer P(NTDT-BDT) comprising NTDT as an electron acceptor and benzo[1,2-b:4,5-b']dithiophene (BDT) as an electron donor are designed and synthesized for producing efficient organic solar cells. The thermal, electronic, photophysical, electrochemical, and structural characteristics of NTDT and P(NTDT-BDT) are studied in detail and compared with those of the widely used bis-lactam acceptor 3,6-dithiophen-2-yl-2,5-dialkylpyrrolo [3,4-c]pyrrole-1,4-dione (DPPT) and its polymer P(DPPT-BDT). Compared to DPPT derivatives, NTDT and P(NTDT-BDT) exhibit remarkably higher absorption coefficients, deeper highest occupied molecular orbital energy levels, and more planar conformations. A bulk heterojunction solar cells based on P(NTDT-BDT) exhibit power conversion efficiency of up to 8.16% with high short circuit current (J(sc)) of 18.51 mA cm(-2), one of the highest J(sc) values yet obtained for BDT-based polymer. Thus, it is successfully demonstrated that the novel bis-lactam unit NTDT is a promising building block for use in organic photovoltaic devices.</P>
Lee, Min Seok,Whang, Dong Ryeol,Choi, Hyun-Jung,Yang, Mun Ho,Kim, Bong-Gi,Baek, Jong-Beom,Chang, Dong Wook Elsevier 2017 Carbon Vol.122 No.-
<P>report efficient modulation of the electrocatalytic activity of imine-rich nitrogen-doped graphene nanosheets (IRnGs) in the oxygen reduction reaction (ORR) by chemical functionalization. IRnGs are prepared by a simple acid-catalyzed dehydration reaction between graphene oxide and aniline derivatives. Various electron-donating and electron-withdrawing substituents are introduced in the para-position of aniline to afford diverse IRnG electrocatalysts. Cyclic voltammetry and rotating ring disk electrode measurements show that the electrocatalytic activity of IRnGs for ORR is highly sensitive to the electronic characteristics of functionalities present in their chemical structures. Thus, the above ORR activities are significantly improved by increasing the electron-withdrawing capability of substituents, since this promotes the beneficial polarization of electrocatalytically active imine bond (-C=N-) in IRnGs. In addition, metal-free IRnGs electrocatalysts offer additional advantages of high selectivity, good long-term stability and excellent tolerance to methanol crossover for ORR in alkaline solution. (C) 2017 Elsevier Ltd. All rights reserved.</P>
Enhanced open-circuit voltages of trifluoromethylated quinoxaline-based polymer solar cells
Putri, Sella Kurnia,Jin, Ho Cheol,Whang, Dong Ryeol,Kim, Joo Hyun,Chang, Dong Wook Elsevier 2019 ORGANIC ELECTRONICS Vol.65 No.-
<P><B>Abstract</B></P> <P>Three quinoxaline-based conjugated polymers with donor-π-acceptor configurations have been synthesized by Stille coupling reaction. The electron-donating 2,3-dioctylthienyl- substituted benzodithiophene (BDT) unit was linked to the electron-accepting 2,3-diphenylquinoxaline (DPQ) group through a thiophene bridge, to produce a reference polymer <B>PTBDT-Qx</B>. Furthermore, the strong electron-withdrawing trifluoromethyl moieties were introduced at the <I>para</I>-position of the phenyl groups in the 2,3-positions of DPQ and 6,7-difluorinated DPQ, to afford <B>PTBDT-QxCF3</B> and <B>PTBDT-FQxCF3</B>, respectively. Owing to the continuous reduction in their HOMO energy levels with increasing number of electron-withdrawing groups, the open-circuit voltage (<I>V</I> <SUB>oc</SUB>) in polymer solar cells (PSCs) shows a gradual improvement in the order of <B>PTBDT-Qx</B> < <B>PTBDT-QxCF3</B> < <B>PTBDT-FQxCF3</B>. The inverted-type PSC based on <B>PTBDT-FQxCF3</B> with a configuration of ITO/ZnO/polymer:PC<SUB>71</SUB>BM/MoO<SUB>3</SUB>/Al provides the best power conversion efficiency of 6.47%, together with a <I>V</I> <SUB>oc</SUB> of 0.99 V, a short-circuit current of 10.03 mA/cm<SUP>2</SUP>, and a fill factor of 65.1%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A series of conjugated polymers based on quinoxaline have been synthesized. </LI> <LI> Incorporation of trifluoromethyl group on the quinoxaline acceptors. </LI> <LI> Optical, electrochemical and photovoltaic properties have been investigated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A series of trifluoromethylated quinoxaline-based polymers were systematically synthesized by Stille coupling reaction. The results obtained in this study clearly reveal the significant contribution of the electron-withdrawing trifluoromethyl groups in enhancing the open-circuit voltages, as well as producing a sharp improvement in the power conversion efficiencies of polymer solar cells with bulk-heterojunction structure.</P> <P>[DISPLAY OMISSION]</P>
Lee Seok Woo,Fan Xiangyang,Whang Dong Ryeol,Jang Ji Won,Choi Hyosung,Chang Dong Wook,Lee Bo Ram 한국정보디스플레이학회 2023 Journal of information display Vol.24 No.3
Optoelectronic devices with organic semiconductors, such as organic light-emitting diodes (OLEDs), have received much attention because they offer ease of processing and device flexibility. However, practical application of these devices is still hindered by relatively poor device performance and lack of cost-effective fabrication process, which represent properties largely determined by the molecular dipole moments of the organic molecules. In this study, we designed and prepared novel quinoxaline-phosphine oxide small molecules (QPSMs) as the electron transport layer (ETL) for the solution-processable OLEDs by tuning the end functional group of the aromatic QPSMs. A key design criterion was controlling the dipole moments of QPSMs, which confers (1) convenient deposition on the emission layer without further annealing through solubility in isopropanol and (2) improved electron injection/transport behavior through effective band level matching of the devices. In particular, the optimized OLEDs with (4-(2,3-bis(4-methoxyphenyl)quinoxalin-5-yl)phenyl)diphenylphosphine oxide (MQxTPPO1) exhibit external quantum efficiency (EQE) of 6.12%. Our results demonstrate the potential application of QPSMs as next-generation ETLs in organic semiconductors.