Direct population of triplet excited states through singlet–triplet transition for visible-light excitable organic afterglow

Yuan, Jie; Chen, Runfeng; Tang, Xingxing; Tao, Ye; Shen, Xu; Jin, Lu; Chen, Cailin; Zhou, X. H.; Zheng, Chao; Huang, Wei

doi:10.1039/c8sc05198d

Cited by 99 publications

(85 citation statements)

References 37 publications

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“…To uncover the mechanism of the pristine CP‐RTP and stimuli‐responsive CP‐OURTP, a set of experimental and theoretical investigations were performed. From time‐dependent density functional theory (TD‐DFT) predicated singlet and triplet excited energies, there are three possible ISC channels between S 1 and T n on the single molecular state with a small singlet and triplet splitting energy (Δ E ST ) lower than 0.37 eV (Tables S2–S5), according to the energy gap law . Owing to the inherently favorable n–π* transition by the heteroatom incorporation of N and O as required by EI‐Sayed′s rule, the spin orbital coupling (SOC) values of these three channels are quite large for efficient ISC as simulated by Dalton calculations (Table S6) .…”

Section: Resultsmentioning

confidence: 99%

Stimuli‐Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence

et al. 2020

Angew Chem Int Ed

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Purely organic materials showing room temperature phosphorescence (RTP) and ultralong RTP (OURTP) have recently attracted much attention. However, it is challenging to integrate circularly polarized luminescence (CPL) into RTP/OURTP. Here, we show a strategy to realize CPL‐active OURTP (CP‐OURTP) by binding an achiral phosphor group directly to the chiral center of an ester chain. Engineering of this flexible chiral chain enables efficient chirality transfer to carbazole aggregates, resulting in strong CP‐OURTP with a lifetime of over 0.6 s and dissymmetry factor of 2.3×10−3 after the conformation regulation upon photo‐activation. The realized CP‐OURTP is thus stable at room temperature but can be deactivated quickly at 50 °C to CP‐RTP with high CPL stability during the photo‐activation/thermal‐deactivation cycles. Based on this extraordinary photo/thermal‐responsive and highly reversible CP‐OURTP/RTP, a CPL‐featured lifetime‐encrypted combinational logic device has been successfully established.

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Section: Resultsmentioning

confidence: 99%

Stimuli‐Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence

et al. 2020

Angew Chem Int Ed

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“…perform exciton conversion to achieve solid-state PL emission in the system, directly populate the triplet excited state, [103] and promote the energy transfer between T 1 and T 1 * in the molecule. [104] In Chapter 5, we will summarize several strategies for realizing solid-state PL of CQDs.…”

Section: Df Processesmentioning

confidence: 99%

Carbon‐Based Quantum Dots with Solid‐State Photoluminescent: Mechanism, Implementation, and Application

Wang

et al. 2020

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Carbon‐based quantum dots (CQDs), including spherical carbon dots and graphene quantum dots, are an emerging class of photoluminescent (PL) materials with unique properties. Great progress has been made in the design and fabrication of high‐performance CQDs, however, the challenge of developing solid‐state PL CQDs have aroused great interest among researchers. A clear PL mechanism is the basis for the development of high‐performance solid‐state CQDs for light emission and is also a prerequisite for the realization of multiple practical applications. However, the extremely complex structure of a CQD greatly limits the understanding of the solid‐state PL mechanism of CQDs. So far, a variety of models have been proposed to explain the PL of solid‐state CQDs, but they have not been unified. This review summarizes the current understanding of the solid‐state PL of solid‐state CQDs from the perspective of energy band theory and electronic transitions. In addition, the common strategies for realizing solid‐state PL in CQDs are also summarized. Furthermore, the applications of CQDs in the fields of light‐emitting devices, anti‐counterfeiting, fingerprint detection, etc., are proposed. Finally, a brief outlook is given, highlighting current problems, and directions for development of solid‐state PL of CQDs.

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“…Thus, organic afterglow efficiency is doomed to be low, considering that only a small part of photoexcited singlet excitons can be transformed to triplet ones through ISC under weak SOC values of purely organic molecules and the nonradiative transitions dominate the triplet exciton decay with the low phosphorescence efficiency at room temperature 8 . Many efforts have been devoted to address this issue, ranging from promoting the ISC process to efficiently populate T 1 and T 1 *,11 , enhancing the intra/ intermolecular interactions to suppress the nonradiative transition 12,13 , to incorporating heavy atoms to facilitate both SOC and ISC rates for emission and exciton transformation [13][14][15][16][17] . But, very few attempts succeed in increasing organic afterglow efficiency to 10%, especially in heavy-atom-free molecules 18,19 ( Supplementary Fig.…”

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confidence: 99%

Thermally activated triplet exciton release for highly efficient tri-mode organic afterglow

et al. 2020

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Developing high-efficient afterglow from metal-free organic molecules remains a formidable challenge due to the intrinsically spin-forbidden phosphorescence emission nature of organic afterglow, and only a few examples exhibit afterglow efficiency over 10%. Here, we demonstrate that the organic afterglow can be enhanced dramatically by thermally activated processes to release the excitons on the stabilized triplet state (T 1 *) to the lowest triplet state (T 1) and to the singlet excited state (S 1) for spin-allowed emission. Designed in a twisted donor-acceptor architecture with small singlet-triplet splitting energy and shallow exciton trapping depth, the thermally activated organic afterglow shows an efficiency up to 45%. This afterglow is an extraordinary tri-mode emission at room temperature from the radiative decays of S 1 , T 1 , and T 1 *. With the highest afterglow efficiency reported so far, the tri-mode afterglow represents an important concept advance in designing high-efficient organic afterglow materials through facilitating thermally activated release of stabilized triplet excitons.

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Direct population of triplet excited states through singlet–triplet transition for visible-light excitable organic afterglow

Abstract: Direct population of triplet states via singlet-to-triplet absorption red-shifts the excitation wavelength and improves the organic afterglow efficiency under ambient conditions.

Cited by 99 publications

References 37 publications

Stimuli‐Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence

Stimuli‐Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence

Carbon‐Based Quantum Dots with Solid‐State Photoluminescent: Mechanism, Implementation, and Application

Thermally activated triplet exciton release for highly efficient tri-mode organic afterglow

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