Ultralong Room-Temperature Phosphorescence from Supramolecular Behavior via Intermolecular Electronic Coupling in Pure Organic Crystals

Pan, Saifei; Chen, Zhentian; Zheng, Xulian; Wu, Donghui; Chen, Guilin; Xu, Jing; Feng, Hui; Qian, Zhaosheng

doi:10.1021/acs.jpclett.8b01697

Cited by 47 publications

(16 citation statements)

References 25 publications

(49 reference statements)

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“…On the other hand, in the case of persistent RTP observed in aggregated state such as crystals, molecular design with charge transfer (CT) characteristics is expected as an important factor for inducing very rigid intermolecular interactions, and this design principle has been verified extensively . That said, some metal‐free aromatic molecules without CT characteristics still show persistent RTP in crystalline state . Particularly, the discussion of the origin of the suppressed k nr (RT) + k q (RT) in crystalline state has not progressed beyond the understanding that it may be induced by the rigidity of the crystalline state.…”

Section: Calculated Parameters Of Transfer Integral Reorganization Ementioning

confidence: 99%

Suppressed Triplet Exciton Diffusion Due to Small Orbital Overlap as a Key Design Factor for Ultralong‐Lived Room‐Temperature Phosphorescence in Molecular Crystals

et al. 2019

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of intramolecular vibrational relaxation and the nonradiative rate (k q (RT)) of triplet quenching due to interactions with ambient surrounding are much larger than k p . Therefore, reports of RTP from metal-free aromatic molecules in ambient condition have been scarce. [8,9] However, in the past 5 years, RTP from metal-free aromatics under ambient conditions has been successfully realized by suppressing k nr (RT) + k q (RT) in various materials, such as host-guest systems, carbon nanodots, and aromatic crystals. [10][11][12][13][14][15][16] In some of these materials, ultralong-lived RTP (persistent RTP) has sufficient intensity and lifetime in air for an observation by naked eye after ceasing the irradiation. [12][13][14][15][16] Due to its ultralong lifetime at RT on the order of seconds, the detection of persistent RTP is not affected by autofluorescence or scattering of the excitation light, [17] and as such can be measured experimentally with low-cost detectors, thus fulfilling one of the requirements for application in bioimaging, optical sensing, and security. [18][19][20][21] For the appearance of persistent RTP under ambient conditions, high efficiency of intersystem crossing (ISC) from the lowest singlet excited state (S 1 ) to the lowest triplet excited state (T 1 ) and suppression of k nr (RT) + k q (RT) are crucial. Efficient ISC from S 1 to T 1 can be obtained by molecular design based on symmetry rules or the El-Sayed rule. [22][23][24] Therefore, the elucidation of the mechanism of suppression of k nr (RT) + k q (RT) is very important factor for persistent RTP. Some heavy atomfree conjugated molecules dispersed in polymers show weak persistent RTP under inert conditions because of the potential suppression of k nr (RT) + k q (RT). [25][26][27][28] However, the analysis of the mechanism of k nr (RT) and k q (RT) suppression was complicated because the experimental separation of the k nr (RT) component from k nr (RT) + k q (RT) was inconclusive. [29] On the other hand, in the case of host-guest systems, the separation of the two nonradiative processes k nr (RT) and k q (RT) was realized by introducing very rigid host matrix with high T 1 energy. The rigid matrix can suppress thermally activated energy transfer over large energy difference from guest molecules to the host and protect from oxygen, resulting in large decrease k nr (RT) + k q (RT) and leading to efficient persistent RTP under ambient conditions. [12] Later, experiments in such rigid hosts revealed that k nr (RT) and k p were intrinsically comparable, [24] Persistent room-temperature phosphorescence (RTP) under ambient conditions is attracting attention due to its strong potential for applications in bioimaging, sensing, or optical recording. Molecular packing leading to a rigid crystalline structure that minimizes nonradiative pathways from triplet state is often investigated for efficient RTP. However, for complex conjugated systems a key strategy to suppress the nonradiative deactivation is not found yet. Here, the origin of small ra...

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Section: Calculated Parameters Of Transfer Integral Reorganization Ementioning

confidence: 99%

Suppressed Triplet Exciton Diffusion Due to Small Orbital Overlap as a Key Design Factor for Ultralong‐Lived Room‐Temperature Phosphorescence in Molecular Crystals

et al. 2019

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“…This causes the energy of the triplet state to return to the ground state in a non-radiative manner. [45][46][47][48][49]…”

Section: Long Lifetime Phosphorescence Propertymentioning

confidence: 99%

A novel strategy for realizing dual state fluorescence and low-temperature phosphorescence

Lei

Dai

Liu

et al. 2019

Mater. Chem. Front.

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“…Two critical strategies, the inhibition of energy dissipation caused by non-radiative transitions and the promotion of intersystem crossing (ISC), have been proposed to develop efficient pure organic RTP materials. The method often adopted to suppress non-radiative transitions is to embed the phosphorescent chromophores into rigid matrixes, such as crystalline − or amorphous hosts at an appropriate concentration. − In the rigid matrix, non-radiative transition channels induced by molecular vibration can be efficiently suppressed and radiative transition turns into the dominant process. It is demonstrated that the enhanced n → π* transition can promote the ISC process, which is beneficial to the generation of efficient RTP. , The organic molecules containing heteroatoms such as O, N, and S or functional groups with lone electron pairs (aldehyde groups, carbonyl groups, CN, etc.)…”

Section: Introductionmentioning

confidence: 99%

Phase- and Halogen-Dependent Room-Temperature Phosphorescence Properties of Biphenylnitrile Derivatives

Xie

Wang

et al. 2021

J. Phys. Chem. C

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The photophysical properties of halogenated biphenylnitrile derivatives (X-BPhN, X = F, Cl, and Br) were systematically investigated, and bromobiphenylnitrile (Br-BPhN)-based solids exhibit phase-dependent room-temperature phosphorescence (RTP) characteristics. The perfect crystalline, lower-quality crystalline, and amorphous solids of Br-BPhN were prepared and exhibited different RTP properties. Two kinds of crystals obtained by slow vacuum gradient sublimation (crystal 1: highquality crystal) and quick solvent evaporation (crystal 2: low-quality crystal) are attributed to an identical crystalline phase. The absolute phosphorescence quantum yields (Φ P ) for crystal 1 and crystal 2 are 9.1 and 6.0%, respectively, while the amorphous sample Br-BPhN has an extremely low Φ P of 1.4%. Theoretical calculations and experimental results demonstrate that multiple intermolecular interactions including halogen bond-induced rigid supramolecular frameworks in the crystalline phase can enhance the RTP of Br-BPhN-based solids. This contribution presents a useful mode molecule to study the mechanism of organic RTP and may provide a feasible approach to develop pure organic phosphors with efficient RTP feature.

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Ultralong Room-Temperature Phosphorescence from Supramolecular Behavior via Intermolecular Electronic Coupling in Pure Organic Crystals

Cited by 47 publications

References 25 publications

Suppressed Triplet Exciton Diffusion Due to Small Orbital Overlap as a Key Design Factor for Ultralong‐Lived Room‐Temperature Phosphorescence in Molecular Crystals

Suppressed Triplet Exciton Diffusion Due to Small Orbital Overlap as a Key Design Factor for Ultralong‐Lived Room‐Temperature Phosphorescence in Molecular Crystals

A novel strategy for realizing dual state fluorescence and low-temperature phosphorescence

Phase- and Halogen-Dependent Room-Temperature Phosphorescence Properties of Biphenylnitrile Derivatives

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