scholarly journals Charge–Transfer Fluorescence and Room-Temperature Phosphorescence from a Bisamide-Based Derivative

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1370
Author(s):  
Chengjian Li ◽  
Chaozheng Zhuo ◽  
Jingwei Sun ◽  
Mi Ouyang
Keyword(s):  
Charge Transfer ◽  
Room Temperature ◽  
Luminescent Properties ◽  
Luminescent Materials ◽  
Room Temperature Phosphorescence ◽  
Single Crystal Structures ◽  
Singlet States ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
The Relationship

The development of organic luminescent materials with bimodal emissions of both fluorescence and room-temperature phosphorescent (RTP) remains a challenge. The investigation of the relationship between fluorescence and RTP performance is especially rare. In this work, we obtained an organic luminescent molecule, 1,4-phenylenebis((9H-carbazol-9-yl)methanone) (PBCM), which exhibits bimodal emissions of cyan fluorescence and yellow RTP in its crystalline state through adopting an electron donor–acceptor–donor (D–A–D) structure. The charge–transfer (CT) effects in the bimodal luminescent properties of PBCM, as well as the single-crystal structures and thermal properties, were investigated. It was found that the CT effect in the singlet states effectively reduces the ∆Est and promotes the ISC processes, resulting in an efficient phosphorescence of PBCM at room temperature. In addition, many strong intermolecular interactions are formed between the donor and acceptor parts of adjacent molecules, leading to the rigid configurations and compact packing of molecules in crystals, which was also confirmed to facilitate the efficient bimodal emissions of PBCM.

scholarly journals A General Design Principle for Aggregation-Induced Room-Temperature Phosphorescence via An sp3-Linked Donor-Acceptor Structure

2020 ◽  
Author(s):  
Tao Wang ◽  
Zhubin Hu ◽  
Xiancheng Nie ◽  
Xiang Sun ◽  
Guoqing Zhang
Keyword(s):  
Single Molecule ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Room Temperature Phosphorescence ◽  
Temperature Estimation ◽  
Emission Color ◽  
Donor And Acceptor ◽  
Color Tunable ◽  
Intramolecular Motion ◽  
Donor Acceptor

<p>Intramolecular motion is commonly more detrimental to room-temperature phosphorescence (RTP) than to prompt fluorescence because long-lived triplet excitons offer more possibilities of quenching. Inspired by the mechanism of aggregation-induced emission (AIE), a single molecule is endowed with AIE and RTP features at the same time. By utilizing triphenylamine (TPA) as AIE activator as well as electron donor and an <i>sp</i><sup>3 </sup>linkers as a bridge between donor and acceptor, five TPA-based AIE-active RTP luminophores were designed. RTP and low-temperature emissions reveal the co-existence of ternary emission, including fluorescence and dual phosphorescence. Single-crystal analyses and theoretical calculations suggest dual phosphorescence derives from local excitation and charge-transfer component. By utilizing hot exciton emission, color-tunable phosphorescence can act as an indicator for temperature estimation. This combinatory approach pioneers a new route for designing versatile AIE-active RTP materials.</p>

scholarly journals Research on Long-Lived Room-Temperature Phosphorescence of Carbazole-Naphthalimide Polylactides

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 790
Author(s):  
Zhiwei Li ◽  
Xingyuan Zhang
Keyword(s):  
Charge Transfer ◽  
Electrochemical Method ◽  
Room Temperature ◽  
Potential Candidate ◽  
Room Temperature Phosphorescence ◽  
Phosphorescence Lifetime ◽  
Donor Acceptor ◽  
Phosphorescence Emission ◽  
Carbazole Group

Two types of naphthalimide derivatives were synthesized by introducing a carbazole group and an n-butyl, respectively, into the naphthalimide system. The electron-donating ability of two kinds of derivatives was investigated by the electrochemical method. These two types of derivatives were used as initiators for the polymerization of d and l-lactide polymerization. Here, the emission and UV-vis absorption serve as the main focus. Compared with solely donor-initiated polylactide (PLA), the PLA with a donor-acceptor structure has a more efficient phosphorescence emission, of which the longest phosphorescence lifetime is up to 407 ms. The experimental results reveal the existence of charge-transfer states in the donor-acceptor-ended polymer. Due to the role of charge-transfer states, a red phosphorescent polymer was developed. Theoretically, these desirable advantages render synthesized PLAs a potential candidate for bioimaging and anti-counterfeiting.

scholarly journals Thermochromic aggregation-induced dual phosphorescence via temperature-dependent sp3-linked donor-acceptor electronic coupling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tao Wang ◽  
Zhubin Hu ◽  
Xiancheng Nie ◽  
Linkun Huang ◽  
Miao Hui ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Electronic Coupling ◽  
Temperature Dependent ◽  
Molecular Systems ◽  
Donor And Acceptor ◽  
Theoretical Investigations ◽  
Donor Acceptor ◽  
And Control ◽  
Two Temperature

AbstractAggregation-induced emission (AIE) has proven to be a viable strategy to achieve highly efficient room temperature phosphorescence (RTP) in bulk by restricting molecular motions. Here, we show that by utilizing triphenylamine (TPA) as an electronic donor that connects to an acceptor via an sp3 linker, six TPA-based AIE-active RTP luminophores were obtained. Distinct dual phosphorescence bands emitting from largely localized donor and acceptor triplet emitting states could be recorded at lowered temperatures; at room temperature, only a merged RTP band is present. Theoretical investigations reveal that the two temperature-dependent phosphorescence bands both originate from local/global minima from the lowest triplet excited state (T1). The reported molecular construct serves as an intermediary case between a fully conjugated donor-acceptor system and a donor/acceptor binary mix, which may provide important clues on the design and control of high-freedom molecular systems with complex excited-state dynamics.

High efficient T-shape deep-red thermally activated delayed fluorescence emitter: substitution position effect

2021 ◽  
Author(s):  
Kai Zhang ◽  
Jianzhong Fan ◽  
Chuankui Wang ◽  
Lili Lin
Keyword(s):  
Charge Transfer ◽  
Position Effect ◽  
Luminescent Properties ◽  
Delayed Fluorescence ◽  
Molecular Structures ◽  
Transfer Property ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
High Efficient ◽  
The Relationship

Modulating the relationship between molecular structures and luminescent properties as well as the charge transfer property for deep-red thermally activated delayed fluorescence (TADF) emitters has always been a powerful challenge,...

scholarly journals Regioisomeric Effect on the Excited-State Fate Leading to Room-Temperature Phosphorescence or Thermally Activated Delayed Fluorescence in a Dibenzophenazine-Cored Donor–Acceptor–Donor System

2021 ◽  
Author(s):  
Takumi Hosono ◽  
Nicolas Oliveira Decarli ◽  
Paola Zimmermann Crocomo ◽  
Tsuyoshi Goya ◽  
Leonardo Evaristo de Sousa ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Room Temperature Phosphorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor Acceptor ◽  
Emission Behavior

Exploring design principle for switching thermally activated dealyed fluorescecne (TADF) and room temperature phosphorescence (RTP) is a fundamentally imporant research in developing triplet-mediated photofunctional organic materials. Herein systematic studies on the regioisomeric and substituents effects in a twisted donor–acceptor–donor (D–A–D) scaffold (A = dibenzo[a,j]phenazine; D = dihydrophenazasiline) on the fate of the excited state have been performed. The study revealed that the regiosiomerism clearly affects the emission behavior of the D–A–D compounds. Distinct difference in TADF, dual TADF & RTP, and dual RTP were observed, depending on the host used. Furthermore, OLED organic light-emitting diodes (OLEDs) fabricated with the developed emitters achieved high external quantum yields for RTP-based OLEDS up to 7.4%.

scholarly journals Molecular insertion regulates the donor-acceptor interactions in cocrystals for the design of piezochromic luminescent materials

2021 ◽  
Author(s):  
Chunguang Zhai ◽  
Xiu Yin ◽  
Shifeng Niu ◽  
Mingguang Yao ◽  
Shuhe Hu ◽  
...  
Keyword(s):  
Intermolecular Interactions ◽  
Luminescent Properties ◽  
Blue Shift ◽  
Luminescent Materials ◽  
Conformation Change ◽  
Emission Enhancement ◽  
Donor Acceptor ◽  
Fine Manipulation

Abstract Developing a universal strategy to design new piezochromic luminescent materials with desirable properties remains challenging. Here, we report that insertion of a non-emissive molecule into a donor (perylene) and acceptor (TCNB) binary cocrystal can realize fine manipulation of intermolecular interactions between perylene and TCNB for desirable piezochromic luminescent properties. A continuous pressure-induced emission enhancement up to 3 GPa and a blue shift from 655 nm to 619 nm have been observed in perylene-TCNB cocrystals upon THF insertion, in contrast to the red-shifted and quenched emission observed when compressing perylene-TCNB cocrystals and other cocrystals reported earlier. By combining experiment with theory, it is further revealed that the inserted non-emissive THF forms blue-shifted H-bonds with neighboring TCNB molecules and promote a conformation change of perylene molecules upon compression, causing the blue-shifted and enhanced emission. This strategy remains valid when inserting other molecules as non-emissive component into perylene-TCNB cocrystals for abnormal piezochromic luminescent behaviors. Our strategy could also be extended to other cocrystals with different donor-acceptor components, opening a new way for designing novel piezochromic luminescent materials for future applications.

scholarly journals Synthesis and Luminescent Properties of Eu3+/Tb3+ Rare Earth Ions Doped Li2SrSiO4 Phosphors

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Kaitao Yu ◽  
Lifang Wei ◽  
Jiaqi Shen
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Band ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Rare Earth Ions ◽  
Luminescent Materials ◽  
Excitation Spectra ◽  
Solid State Method ◽  
X Ray ◽  
Uv Visible

The series of luminescent materials of Eu3 +, Tb3 + doped Li2SrSiO4 were synthesized by a high-temperature solid-state method. The phase purity of the samples was measured by X-ray powder diffraction (XRD). The luminescent properties of the samples were studied by UV-visible excitation spectra and emission spectra The It is found that the strong absorption of Eu3 + doped Li2-xSr1-xEuxSiO4 is from the 250 ~ 290 nm charge transfer band of Eu3 + and the 7F0 → 5L6 absorption transition of 393 nm. The strongest emission of the emission spectra at 393 nm is 614 nm and 701 nm, respectively, from the 5D0 → 7F2 and 5D0 → 7F4 transitions of Eu3 +. Tb3 + doped sample Li2-xSr1-xTb xSiO4 excitation spectrum is mainly composed of Tb3 + ion fd transition and charge transfer band composed of broadband, the strongest absorption at 269 nm, the emission of the main emission of 5D4 → 7F5 transition (542 nm).

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