Triplet Excitation Energy Transfer in Choleic Acid Crystals

국성근 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.12

Time resolved phosphorescence of Dibromobenzophenone (DBBP) choleic acid crystal was observed at 4.2 K as functions of excitation energy and delay time. The experimental results reveal that the energy transfer efficiency is dependent on the excitation energy, i.e. the density of acceptors sites. As the excitation energy or delay time increases, the resonance phosphorescence does not broaden and shift gradually, rather a broad luminescence band develops about 290 cm-1 to lower energy of the resonance phosphorescence. The observation implies that energy transfer from high to low energy sites in this system is controlled by emission of phonons or vibrons. The data of time resolved experiments were analyzed in terms of a mechanism involving direct donor-acceptor excitation transport by exchange coupling. It was concluded that an isotropic two-dimensional exchange interaction topology is consistent with energy transfer in this system.

Color mixing between phosphorescence and fluorescence by incomplete F?rster energy transfer

조성민,Jaesoo Choi,Dong-Hyun Lee,채희엽,박진호 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.1

We have successfully showed the color mixing between fluorescence and phosphorescence by the incomplete Förster energy transfer. The emission color from fluorescent Rubrene and phosphorescent Ir(ppy)3 was found possible to be mixed for a single-layer device doped with both dyes, maintaining the high luminance efficiency of the phosphorescence. We also found out that the Förster energy transfer was very efficient and independent of the applied voltage with no loss of energy during the transfer

Triplet Excitation Energy Transfer in Choleic Acid Crystals

Kook, Seong-Keun Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.12

Time resolved phosphorescence of Dibromobenzophenone (DBBP) choleic acid crystal was observed at 4.2 K as functions of excitation energy and delay time. The experimental results reveal that the energy transfer efficiency is dependent on the excitation energy, i.e. the density of acceptors sites. As the excitation energy or delay time increases, the resonance phosphorescence does not broaden and shift gradually, rather a broad luminescence band develops about 290 cm?1 to lower energy of the resonance phosphorescence. The observation implies that energy transfer from high to low energy sites in this system is controlled by emission of phonons or vibrons. The data of time resolved experiments were analyzed in terms of a mechanism involving direct donor-acceptor excitation transport by exchange coupling. It was concluded that an isotropic twodimensional exchange interaction topology is consistent with energy transfer in this system.

Deep blue phosphorescent iridium(III) cyclometalates with <i>o</i>-carboranes

Kim, Minji,Lee, Min Hyung Elsevier Sequoia 2018 Journal of organometallic chemistry Vol.870 No.-

<P><B>Abstract</B></P> <P>Heteroleptic iridium(III) cyclometalates, [5-(2-MeCB)dfppy]<SUB>2</SUB>Ir(LX) (2-MeCB = 2-methyl-<I>o</I>-carboran-1-yl; dfppy = 2-(4,6-difluorophenyl)pyridinato-C<SUP>2</SUP>,N; LX = picolinate (<B>5a</B>) or tetrakis(1-pyrazolyl)borate (<B>5b</B>)), with <I>o</I>-carborane at the 5-position of the phenyl ring of the dfppy ligand were prepared to investigate the impact of the <I>o</I>-carborane cage on the blue phosphorescence of complexes. X-ray diffraction analysis of <B>5a</B> revealed a distorted octahedral coordination geometry around the iridium center with the peripheral carborane substitution of the dfppy ligand. The absorption and emission bands of <B>5a</B> and <B>5b</B> were hypsochromically shifted relative to those of the sky blue (dfppy)<SUB>2</SUB>Ir(pic) (FIrpic) complex, resulting in deep blue phosphorescence (<I>λ</I> <SUB>PL</SUB> = 459 nm for <B>5a</B> and 452 nm for <B>5b</B> vs. 468 nm for FIrpic). The complexes showed high to moderate quantum efficiencies in toluene (Φ<SUB>PL</SUB> = 0.89 for <B>5a</B>; 0.47 for <B>5b</B>) and in PMMA film (Φ<SUB>PL</SUB> = 0.45 for <B>5a</B>; 0.34 for <B>5b</B>), despite a large decrease in quantum efficiency in THF. A slight decrease in quantum efficiency was observed with increasing doping concentrations of the complexes in PMMA films, indicating suppression of the emission quenching owing to the steric bulkiness of the 2-Me-<I>o</I>-carborane cage. Anodic shifts in the oxidation potentials of <B>5a</B> and <B>5b</B> compared with that of FIrpic indicated that the stabilization of the HOMO level by the inductive electron-withdrawing effect of the <I>o</I>-carborane is responsible for the deep blue emission of <B>5a</B> and <B>5b</B>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>o</I>-Carborane-appended heteroleptic Ir(III) cyclometalates [5-(2-MeCB)dfppy]<SUB>2</SUB>Ir(LX) were prepared. </LI> <LI> The complexes exhibited deep blue phosphorescence. </LI> <LI> The stabilization of the HOMO level by <I>o</I>-carborane substitution was responsible for the deep blue emission. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Pure blue phosphorescence by new <i>N-</i>heterocyclic carbene-based Ir(III) complexes for organic light-emitting diode application

Sarada, Ganguri,Maheshwaran, Athithan,Cho, Woosum,Lee, Taegyun,Han, Si Hyun,Lee, Jun Yeob,Jin, Sung-Ho Elsevier 2018 Dyes and pigments Vol.150 No.-

<P><B>Abstract</B></P> <P>Pure blue phosphorescence with high quantum yield is crucial, yet highly challenging to achieve, for the successful application of phosphorescent organic light-emitting diodes (PhOLEDs) in display and lighting technologies. This study presents the design of three meridional tris-cyclometalated Ir(III) complexes (Ir1, Ir2 and Ir3) by introducing diphenylphosphine oxide (Ph<SUB>2</SUB>P = O) and/or fluorine (-F) group(s) on <I>N</I>-heterocyclic carbene (NHC) ligands (3-phenyl-3<I>H</I>-imidazo[4,5-<I>b</I>]pyridine or 1-phenyl-1<I>H</I>-imidazole) with the aim of achieving pure blue phosphorescence. Particularly, the introduction of –F on the NHC ligand greatly enhances the triplet (T<SUB>1</SUB>) energy and photoluminescence (PL) intensity of the Ir(III) complex (Ir3). Consequently, Ir3 exhibits ‘pure’ blue phosphorescence with high quantum yield (95%) and short triplet lifetimes (τ), the latter being beneficial for high radiative decay rates. Moreover, the Ir3 emitter shows pure blue Commission Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.08), especially the ‘pure’ blue CIE <I>y</I> coordinate, in the PhOLEDs. However, Ir1 shows a maximum external quantum efficiency (EQE) of 8.6% at higher dopant concentration (20 wt%) with CIE coordinates of (0.16, 0.12).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three <I>N-</I>heterocyclic carbene based Ir(III) complexes were synthesized. </LI> <LI> Investigated the functionalization with diphenylphosphine oxide or fluorine. </LI> <LI> Achieved pure ‘blue’ coordinates (0.16, 0.08) for Ir3. </LI> <LI> The triplet energies of the phosphors are increased by the functionalization. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Highly Efficient Red Phosphorescent Dopants in Organic Light‐Emitting Devices

Kim, Do Han,Cho, Nam Sung,Oh, Hyoung‐,Yun,Yang, Joong Hwan,Jeon, Woo Sik,Park, Jung Soo,Suh, Min Chul,Kwon, Jang Hyuk WILEY‐VCH Verlag 2011 ADVANCED MATERIALS Vol.23 No.24

<P><B>Highly efficient red phosphorescent</B> <B>dopants</B> in organic light‐emitting devices have been explored by using a cyclometalated iridium complex with a fully methylated phenyl ring and a quinoline ring as well as a sterically crowded ancillary ligand. The red phosphorescent devices with these dopants give extremely high external quantum efficiencies.</P>

Phosphorescence-based cell-free DNA detection using lipid-polymer hybrid nanoparticles having organic phosphors

Do Hyun Kang,Jinsang Kim 한국생산제조학회 2020 한국생산제조시스템학회 학술발표대회 논문집 Vol.2020 No.10

발광 재료용 다이포스핀-다이골드 착물의 합성과 특성 연구

김준호(Kim JunHo),손병청(Sohn ByungChung),하윤경(Ha YunKyoung) 한국유화학회 2002 한국응용과학기술학회지 Vol.19 No.2

Diphosphine dinuclear gold(I) complexes were synthesized from the reaction of bridged diphosphines and gold ions. As a bridged diphosphine, 1,2-bis(diphenylphosphino)metbane (dppm) or 1,1 -Bis(diphenylphosphino) ferrocene (dppf) was introduced. As anionic ligands, CI was first coordinated to Au, resulting in (diphosphine)(AuCl)_{2}. Then, the ligand, SPh, was substituted for Cl in the chloride complex to give (diphosphine)(AuSPh)_{2. As a result, three digold complexes, (dppm)(AuCl)_{2}. (I), (dppf)$(AuCl)_{2}. (II), and (dppf)(AuSPh_{2}. (III) were prepared in this study. The thermal properties were investigated at first hand to confirm that the gold complexes were in fact formed. The digold complexes were decomposed above 200^{\circ}C while the ligand, dppm or dppf, melts under 180^{\circ}CThe photoluminescence (PL) spectra of the spin-coated thin films showed the maximum peak at 590, 595, and 540nm for the complex, I, II, and III, respectively. These complexes were found to give the orange color phosphorescence. Therefore, these digold complexes can be candidates for orange-red phosphorescent materials in organic electroluminescent devices (OELD). Further studies on application of the complexes as a dopant in an emitting layer are in progress in our laboratory.

Phosphorescent Azacrown Ether-appended Iridium (III) Complex for the Selective Detection of Hg^2+ in Aqueous Acetonitrile

Yinan Li,윤웅찬,현명호 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.1

A new phosphorescent cyclometalated heteroleptic iridium (III) complex with an ancillary ligand of 4-azacrownpicolinate was prepared and its metal ion selective phosphorescent chemosensing behavior was investigated. The new iridium (III) complex exhibits notable phosphorescence quenching for Hg^2+ in aqueous 50% acetonitrile solution with respect to the selective phosphorescent detection of various metal ions including Li^+, Na^+, K^+, Cs^+, Mg^2+, Ca^2+,Ba^2+, Fe^2+, Ni^2+, Cu^2+, Zn^2+, Ag^+, Pb^2+, Cd^2+, Cr^2+, Cr^3+ and Hg^2+. The phosphorescence quenching for Hg^2+ increased linearly with increasing concentration of Hg^2+ in the range of 10 μM - 700 μM even in the presence of other metal ions,except for Cu^2+. Consequently, the new iridium (III) complex has the potential to be utilized for the determination of parts per million levels of Hg^2+ in aqueous acetonitrile media.

Phosphorescent Azacrown Ether-appended Iridium (III) Complex for the Selective Detection of Hg²⁺ in Aqueous Acetonitrile

Li, Yinan,Yoon, Ung-Chan,Hyun, Myung-Ho Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.1

A new phosphorescent cyclometalated heteroleptic iridium (III) complex with an ancillary ligand of 4-azacrownpicolinate was prepared and its metal ion selective phosphorescent chemosensing behavior was investigated. The new iridium (III) complex exhibits notable phosphorescence quenching for Hg2+ in aqueous 50% acetonitrile solution with respect to the selective phosphorescent detection of various metal ions including $Li^+,Na^+,K^+,Cs^+,Mg^{2+},Ca^{2+},Ba^{2+},Fe^{2+},Ni^{2+},Cu^{2+},Zn^{2+},Ag^+,Pb^{2+},Cd^{2+},Cr^{2+},Cr^{3+}$ and $Hg^{2+}$. The phosphorescence quenching for $Hg^{2+}$ increased linearly with increasing concentration of $Hg^{2+}$ in the range of $10{\mu}M-700{\mu}M$ even in the presence of other metal ions, except for $Cu^{2+}$. Consequently, the new iridium (III) complex has the potential to be utilized for the determination of parts per million levels of $Hg^{2+}$ in aqueous acetonitrile media.