scholarly journals Tuning the singlet-triplet energy gap: a unique approach to efficient photosensitizers with aggregation-induced emission (AIE) characteristics

2015 ◽  
Vol 6 (10) ◽  
pp. 5824-5830 ◽  
Author(s):  
Shidang Xu ◽  
Youyong Yuan ◽  
Xiaolei Cai ◽  
Chong-Jing Zhang ◽  
Fang Hu ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Energy Gap ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Triplet Energy ◽  
Aggregation Induced Emission ◽  
Unique Approach ◽  
Triplet Excited States

The efficiency of the intersystem crossing process can be improved by reducing the energy gap between the singlet and triplet excited states (ΔEST), which offers the opportunity to improve the yield of the triplet excited state.

Preparation of Bodipy–ferrocene dyads and modulation of the singlet/triplet excited state of bodipy via electron transfer and triplet energy transfer

2016 ◽  
Vol 4 (14) ◽  
pp. 2843-2853 ◽  
Author(s):  
Xueyan Wu ◽  
Wenting Wu ◽  
Xiaoneng Cui ◽  
Jianzhang Zhao ◽  
Mingbo Wu
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Excited State ◽  
Excited States ◽  
Singlet Excited State ◽  
Triplet Excited State ◽  
Triplet Energy ◽  
Triplet Excited States ◽  
Triplet Energy Transfer

Bodipy–ferrocene dyads were prepared for reversible electrochemical switching of the singlet excited state (fluorescence), as well as the triplet excited states of Bodipy.

scholarly journals Orthogonally Aligned Cyclic BODIPY Arrays with Long-lived Triplet Excited States as Efficient Heavy-Atom-Free Photosensitizers

2021 ◽  
Author(s):  
Zhaoyang Zhu ◽  
Xue Zhang ◽  
Xing Guo ◽  
Qing-Hua Wu ◽  
Zhongxin Li ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Excited State ◽  
Excited States ◽  
Heavy Atom ◽  
Triplet Excited State ◽  
Transfer Processes ◽  
Excited State Lifetimes ◽  
Triplet Excited States

Photosensitizers with long triplet excited state lifetimes are key to their efficient electron transfer or energy transfer processes. Herein, we report a novel class of cyclic trimeric BODIPY arrays which...

scholarly journals Computational investigation on the large energy gap between the triplet excited-states in acenes

RSC Advances ◽  
2017 ◽  
Vol 7 (43) ◽  
pp. 26697-26703 ◽  
Author(s):  
Y. Y. Pan ◽  
J. Huang ◽  
Z. M. Wang ◽  
D. W. Yu ◽  
B. Yang ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Organic Materials ◽  
Energy Gap ◽  
Great Influence ◽  
Accurate Description ◽  
Large Energy ◽  
Computational Investigation ◽  
State Behavior ◽  
Triplet Excited States

Accurate description triplet excited states is a challenge of organic materials. In this work, we investigate excited state behavior of acenes. The results show that the symmetry of the transition orbital have a great influence on the energy gap.

scholarly journals Interaction of Triplet Excited States of Ketones with Nucleophilic Groups: (π,π*) and (n,π*) versus (σ*,π*) States. Substituent-Induced State Switching in Triplet Ketones

2017 ◽  
Vol 70 (4) ◽  
pp. 387 ◽  
Author(s):  
Götz Bucher
Keyword(s):  
Excited State ◽  
Excited States ◽  
Intramolecular Interaction ◽  
Triplet States ◽  
Triplet Excited State ◽  
Excitation Energies ◽  
Exciplex Formation ◽  
Lone Pairs ◽  
Triplet Excited States ◽  
Spin Densities

The intramolecular interaction of ketone triplet excited states with nucleophilic substituents is investigated by studying the electronic properties of phenalenone and a range of phenalenones functionalized in position 9 as a model system. In accordance with the literature, a (π,π*) triplet excited state is predicted for phenalenone. Similarly, 9-fluoro-, 9-chloro-, and 9-methoxyphenalenone are calculated to have (π,π*) lowest triplet excited states, whereas the lowest triplet states of 9-bromo-, 9-iodo, 9-methylthio, and 9-dimethylaminophenalenone are predicted to have (σ*,π*) character. As a result of the interaction between halogen and oxygen lone pairs increasing with increasing orbital size, the antibonding linear combination of substituent lone pairs with oxygen lone pairs sufficiently rises in energy to change the character of the lowest triplet excited state of the 9-substituted phenalenones from (π,π*) to (σ*,π*). These unusual triplet excited states or exciplexes should essentially behave like (n,π*) triplets states, but will differ from pure (n,π*) states by showing significant spin densities at the substituent heteroatoms, predicted to reach values of 0.25 for 9-iodophenalenone, and ~0.5 for 9-dimethylaminophenalenone. Vertical T1–T2 excitation energies calculated indicate that the stabilization of the (σ*,π*) relative to the (π,π*) state can reach 1 eV. Preliminary calculations on the triplet excited states of 2-iodobenzophenone, 4-iodo-2-butanone, and iodoacetone indicate that intramolecular triplet exciplex formation should be a general phenomenon, as long as the ring being formed is at least a five-membered ring.

scholarly journals Influence of energy gap between charge-transfer and locally excited states on organic long persistence luminescence

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zesen Lin ◽  
Ryota Kabe ◽  
Kai Wang ◽  
Chihaya Adachi
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Energy Gap ◽  
Persistent Luminescence ◽  
Triplet Excited State ◽  
Exciton Energy ◽  
Selection Strategies ◽  
Molecular Selection ◽  
Spectra Properties

AbstractOrganic long-persistent luminescence (LPL) is an organic luminescence system that slowly releases stored exciton energy as light. Organic LPL materials have several advantages over inorganic LPL materials in terms of functionality, flexibility, transparency, and solution-processability. However, the molecular selection strategies for the organic LPL system still remain unclear. Here we report that the energy gap between the lowest localized triplet excited state and the lowest singlet charge-transfer excited state in the exciplex system significantly controls the LPL performance. Changes in the LPL duration and spectra properties are systematically investigated for three donor materials having a different energy gap. When the energy level of the lowest localized triplet excited state is much lower than that of the charge-transfer excited state, the system exhibits a short LPL duration and clear two distinct emission features originating from exciplex fluorescence and donor phosphorescence.

scholarly journals Triplet energies and excimer formation in meta - and para -linked carbazolebiphenyl matrix materials

2015 ◽  
Vol 373 (2044) ◽  
pp. 20140446 ◽  
Author(s):  
Sergey A. Bagnich ◽  
Alexander Rudnick ◽  
Pamela Schroegel ◽  
Peter Strohriegl ◽  
Anna Köhler
Keyword(s):  
Excited State ◽  
Triplet State ◽  
Spectroscopic Investigation ◽  
Triplet Excited State ◽  
Conjugation Length ◽  
Triplet Energy ◽  
Excimer Formation

We present a spectroscopic investigation on the effect of changing the position where carbazole is attached to biphenyl in carbazolebiphenyl (CBP) on the triplet state energies and the propensity to excimer formation. For this, two CBP derivatives have been prepared with the carbazole moieties attached at the ( para ) 4- and 4 ′ -positions ( p CBP) and at the ( meta ) 3- and 3 ′ -positions ( m CBP) of the biphenyls. These compounds are compared to analogous m CDBP and p CDBP, i.e. two highly twisted carbazoledimethylbiphenyls, which have a high triplet energy at about 3.0 eV and tend to form triplet excimers in a neat film. This torsion in the structure is associated with localization of the excited state onto the carbazole moieties. We find that in m CBP and p CBP, excimer formation is prevented by localization of the triplet excited state onto the central moiety. As conjugation can continue from the central biphenyls into the nitrogen of the carbazole in the para -connected p CBP, emission involves mainly the benzidine. By contrast, the meta -linkage in m CBP limits conjugation to the central biphenyl. The associated shorter conjugation length is the reason for the higher triplet energy of 2.8 eV in m CBP compared with the 2.65 eV in p CBP.

Effects of extending the π-conjugation of the acetylide ligand on the photophysics and reverse saturable absorption of Pt(ii) bipyridine bisacetylide complexes

2016 ◽  
Vol 18 (41) ◽  
pp. 28674-28687 ◽  
Author(s):  
Taotao Lu ◽  
Chengzhe Wang ◽  
Levi Lystrom ◽  
Chengkui Pei ◽  
Svetlana Kilina ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Substituent Effect ◽  
Excited State Absorption ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Triplet Excited State ◽  
Near Ir ◽  
Terminal Substituent ◽  
Acetylide Ligand

Extending the acetylide ligand π-conjugation diminishes the terminal substituent effect on the lowest excited states, but expands the triplet excited-state absorption to the near-IR region.

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