| 1. |
- Ahmad, Shargeel, et al.
(författare)
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Photon Up-Conversion via Epitaxial Surface-Supported Metal-Organic Framework Thin Films with Enhanced Photocurrent
- 2018
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:2, s. 249-253
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Tidskriftsartikel (refereegranskat)abstract
- We report a new triplet-triplet annihilation photon up-conversion (TTA-UC) system using an epitaxial Zn-perylene surface-supported metal-organic framework (SURMOF) grown on metal oxide surface as "emitter", and a platinum octaethylporphyrin (PtOEP) as "sensitizer" in [Co(bpy)(3)](2+/3+) acetonitrile solution. It has been demonstrated that the photocurrent can be significantly enhanced relative to epitaxial Zn-perylene SURMOF due to the TTA-UC mechanism. This initial result holds promising applications toward SURMOF-based solar energy conversion devices.
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| 2. |
- Hussain, Mushraf, et al.
(författare)
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Spin-Orbit Charge-Transfer Intersystem Crossing of Compact Naphthalenediimide-Carbazole Electron-Donor-Acceptor Triads
- 2021
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 125:38, s. 10813-10831
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Tidskriftsartikel (refereegranskat)abstract
- Compact electron donor–acceptor triads based on carbazole (Cz) and naphthalenediimide (NDI) were prepared to study the spin–orbit charge-transfer intersystem crossing (SOCT-ISC). By variation of the molecular conformation and electron-donating ability of the carbazole moieties, the electronic coupling between the two units was tuned, and as a result charge-transfer (CT) absorption bands with different magnitudes were observed (ε = 4000–18 000 M–1 cm–1). Interestingly, the triads with NDI attached at the 3-C position or with a phenyl spacer at the N position of the Cz moiety, thermally activated delayed fluorescence (TADF) was observed. Femtosecond transient absorption (fs-TA) spectroscopy indicated fast electron transfer (0.8–1.5 ps) from the Cz to NDI unit, followed by population of the triplet state (150–600 ps). Long-lived triplet states (up to τT = 45–50 μs) were observed for the triads. The solvent-polarity-dependent singlet-oxygen quantum yield (ΦΔ) is 0–26%. Time-resolved electron paramagnetic resonance (TREPR) spectral study of TADF molecules indicated the presence of the 3CT state for NDI-Cz-Ph (zero-field-splitting parameter D = 21 G) and an 3LE state for NDI-Ph-Cz (D = 586 G). The triads were used as triplet photosensitizers in triplet–triplet annihilation upconversion by excitation into the CT absorption band; the upconversion quantum yield was ΦUC = 8.2%, and there was a large anti-Stokes shift of 0.55 eV. Spatially confined photoexcitation is achieved with the upconversion using focusing laser beam excitation, and not the normally used collimated laser beam, i.e., the upconversion was only observed at the focal point of the laser beam. Photo-driven intermolecular electron transfer was demonstrated with reversible formation of the NDI–• radical anion in the presence of the sacrificial electron donor triethanolamine.
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| 3. |
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| 4. |
- Li, Ling, et al.
(författare)
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Efficient organic dye sensitized solar cells based on modified sulfide/polysulfide electrolyte
- 2011
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 21:15, s. 5573-5575
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Tidskriftsartikel (refereegranskat)abstract
- An energy conversion efficiency of up to 5.24% has been attained, under AM 1.5 G illumination for a new dye-sensitized solar cell using TH305, as a low cost organic dye, ((CH3)(4)N)(2)S/((CH3)(4)N)(2)S-2, as an organic electrolyte and CoS as counter electrode.
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| 5. |
- Li, Ling, et al.
(författare)
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Electric characteristics of MgO-doped TiO2 nanocrystalline film in dye-sensitized solar cells
- 2011
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Ingår i: Application Of Chemical Engineering, Pts 1-3. - : Trans Tech Publications Inc.. - 9783037851210 ; , s. 2106-2109
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Konferensbidrag (refereegranskat)abstract
- TiO2 were doped with MgO by thermal hydrolysis, The photoelectrochem. properties of the 1%MgO-doped TiO2 film matched with org. dye TH305 were better than those of the anatase TiO2 film. The conduction band of the MgO doped nanostructured TiO2 synthesized neg. shifted by 60 mV, compared to that of undoped TiO2.
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| 6. |
- Li, Ling, et al.
(författare)
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Highly Efficient CdS Quantum Dot-Sensitized Solar Cells Based on a Modified Polysulfide Electrolyte
- 2011
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 133:22, s. 8458-8460
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Tidskriftsartikel (refereegranskat)abstract
- A modified polysulfide redox couple, [(CH(3))(4)N](2)S/[(CH(3))(4)N](2)S(n), in an organic solvent (3-methoxypropionitrile) was employed in CdS quantum dot (QD)-sensitized solar cells (QDSSCs), and an unprecedented energy conversion efficiency of up to 3.2% was obtained under AM 1.5 G illumination. The QDs were linked to nanoporous TiO(2) via covalent bonds by using thioglycolic acid, and chemical bath deposition in an organic solvent was then used to prepare the QDSSCs, facilitating high wettability and superior penetration capability of the TiO(2) films. A very high fill factor of 0.89 was observed with the optimized QDSSCs.
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| 7. |
- Ni, Wenjun, et al.
(författare)
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Singlet Fission from Upper Excited Electronic States of Cofacial Perylene Dimer
- 2019
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 10:10, s. 2428-2433
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Tidskriftsartikel (refereegranskat)abstract
- Singlet fission directly from the upper excited vibrational and electronic states of cofacial perylene dimers, bypassing the relaxed state S-1, was detected within 50 fs. This process competes well with vibrational cooling in S-1 (4.7-7.0 ps) and S-2 -> S-1 internal conversion (380 fs). The singlet fission has the energy threshold E = 3.06 eV. Other competitive relaxation processes are excimer and dimer cation formation on an ultrafast time scale. Excitation to higher energy levels (4.96 eV) leads to a higher efficiency of singlet fission.
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| 8. |
- Yang, Lei, et al.
(författare)
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Sulfur vs. tellurium: the heteroatom effects on the nonfullerene acceptors
- 2019
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Ingår i: Science in China Series B. - : SCIENCE PRESS. - 1674-7291 .- 1869-1870. ; 62:7, s. 897-903
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Tidskriftsartikel (refereegranskat)abstract
- The effect of chalcogen heteroatom variation on donor materials has been systematically investigated. However, this effect on acceptors has rarely been explored. Herein, nonfullerene acceptors BFPSP and BFPTP were reported by simply changing the chalcogen atoms from S to Te. The differences between BFPSP and BFPTP in light absorption, energy levels, excited-state lifetimes, energy loss, charge mobilities, morphology, and photovoltaic properties were systematically investigated to understand the heteroatom effects. More importantly, the electroluminescence spectra, external quantum efficiency of photovoltaics and TD-DFT calculations revealed that the triplet excited state (T-1) in energy of BFPTP equals to the charge transfer (CT) state in PBDB-T:BFPTP, which allows T-1 excitons, generated by intersystem crossing, to split into free charges to contribute to the efficiency. This contribution provides a strategy for tuning the photophysical properties of nonfullerene acceptors and designing high performance triplet materials for OSCs.
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