scholarly journals Negative Singlet–Triplet Excitation Energy Gap in Triangle-Shaped Molecular Emitters for Efficient Triplet Harvesting

2021 ◽  
Author(s):  
J. Sanz-Rodrigo ◽  
G. Ricci ◽  
Y. Olivier ◽  
J. C. Sancho-García
Keyword(s):  
Excitation Energy ◽  
Energy Gap ◽  
Triplet Excitation ◽  
Triplet Harvesting

scholarly journals Two-photon-excited ultralong organic room temperature phosphorescence by dual-channel triplet harvesting

2019 ◽  
Vol 10 (31) ◽  
pp. 7352-7357 ◽  
Author(s):  
Zhu Mao ◽  
Zhan Yang ◽  
Chao Xu ◽  
Zongliang Xie ◽  
Long Jiang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Energy Gap ◽  
Infrared Laser ◽  
Concentration Quenching ◽  
Ambient Conditions ◽  
Room Temperature Phosphorescence ◽  
Small Energy ◽  
Two Photon ◽  
Dual Channel ◽  
Triplet Harvesting

Small energy gap boosts dual-channel triplet harvesting via TADF and UOP, which suppresses long-lived triplet concentration quenching. An infrared laser (808 nm) is able to induce persistent emission under ambient conditions.

Synthesis, optical characterization, and TD-DFT studies of novel mero/bis-mero cyanine dyes based on N-Bridgehead heterocycles

2019 ◽  
Vol 97 (3) ◽  
pp. 219-226
Author(s):  
Ahmed I. Koraiem ◽  
Islam M. Abdellah ◽  
Ahmed El-Shafei ◽  
Fathy F. Abdel-Latif ◽  
Reda M. Abd El-Aal
Keyword(s):  
Excitation Energy ◽  
Density Functional ◽  
Energy Gap ◽  
Solvent Polarity ◽  
Cyanine Dyes ◽  
Spectral Studies ◽  
Functional Theory ◽  
Td Dft ◽  
Homo Lumo ◽  
Good Agreement

Novel mero/bis-mero cyanine dyes based on N-Bridgehead imidazo[1,2-g]quinolino[2,1-a][2,6]naphthyridine have been synthesized and characterized to evaluate intramolecular charge transfer (ICT) effect on the energy gap (E0-0). The UV–vis and emission spectral studies revealed that dyes are absorbed in the region of λmax 485–577 nm and emitted at 567–673 nm. Their solvatochromic behavior in solvents of various polarities, CCl4, C6H6, H2O, CHCl3, acetone, and DMF, was studied to emphasize the effect of solvent polarity on the absorption maxima, molar extinction coefficients of the dyes, and excitation energy of the dyes. Their electron cloud delocalization in HOMO/LUMO levels were studied by DFT using Gaussian 09 software. Time-dependent density functional theory (TD-DFT) was applied to theoretically explore the first excitation energy (E0-0) of these dyes, which was in good agreement with experimental results.

UPS of a-Si:H: What is the energy of the Er 4f states?

2000 ◽  
Vol 609 ◽  
Author(s):  
Leandro R. Tessler ◽  
Cínthia Piamonteze ◽  
Ana Carola Iniguez ◽  
Abner de Siervo ◽  
Richard Landers ◽  
...  
Keyword(s):  
Binding Energy ◽  
Excitation Energy ◽  
Cross Section ◽  
Energy Gap ◽  
Valence States ◽  
Erbium Doped ◽  
Order Of Magnitude ◽  
Synchrotron Light ◽  
The Cross ◽  
Er Doped

ABSTRACTOne very important problem concerning erbium-doped silicon is the electronic structure of the Er3+ impurities. In particular, it is still not clear if the 4f levels can be treated as frozen core levels or their overlap with s and p states of their neighbors must be considered explicitly. For crystalline Si, the 4f levels have been supposed to be anywhere between 20 eV below the valence band and within the energy gap. In this paper we report on the first ultraviolet photoemission spectroscopy (UPS) measurements on Er-doped a-Si:H. Samples of a-Si:H<Er> with different Er contents (up to 1 at. % Er) were prepared by co-sputtering from a Si target partially covered with metallic Er platelets. In order to enhance the Er states relative to the Si and H states, the excitation energy was tuned between 40 and 140 eV with a synchrotron light source. At 140 eV excitation energy the cross-section of the Er 4f and 5p states is more than an order of magnitude higher than the cross section of the Si 3s or 3p states. As the Er concentration increases, a shoulder and then a peak appears at 10.0±0.5 eV binding energy. The intensity and width of this peak is well correlated with the Er concentration, and with the Er 5p and 5p½ levels at 26 and 32 eV binding energy, respectively. We attribute the peak at 10.0±0.5 eV binding energy to the Er 4f level. These are the only occupied states that can be related to the presence of Er, indicating that these levels are not valence states and consequently can be treated as frozen core levels.

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