Understanding the potential for efficient triplet harvesting with hot excitons

2019 ◽  
Vol 216 ◽  
pp. 395-413 ◽  
Author(s):  
T. Northey ◽  
T. Keane ◽  
J. Eng ◽  
T. J. Penfold
Keyword(s):  
Excited State ◽  
Excited States ◽  
Disordered Systems ◽  
State Energy ◽  
Electronically Excited States ◽  
Excited State Energy ◽  
Natural Systems ◽  
Electronically Excited ◽  
Significant Attention ◽  
Triplet Harvesting

Excited state energy transfer in disordered systems has attracted significant attention owing to the importance of this phenomenon in both artificial and natural systems that operate in electronically excited states.

scholarly journals Theoretical Electronic and Rovibrational Studies for Anions of Interest to the DIBs

2013 ◽  
Vol 9 (S297) ◽  
pp. 344-348 ◽  
Author(s):  
R. C. Fortenberry
Keyword(s):  
Excited State ◽  
Excited States ◽  
State Of The Art ◽  
Spectroscopic Constants ◽  
Coupled Cluster ◽  
Electronic Excitations ◽  
Electronically Excited States ◽  
Coupled Cluster Theory ◽  
Electronically Excited ◽  
Enolate Anion

AbstractThe dipole-bound excited state of the methylene nitrile anion (CH2CN−) has been suggested as a candidate carrier for a diffuse interstellar band (DIB) at 803.8 nm. Its corresponding radical has been detected in the interstellar medium (ISM), making the existence for the anion possible. This work applies state-of-the-art ab initio methods such as coupled cluster theory to reproduce accurately the electronic excitations for CH2CN− and the similar methylene enolate anion, CH2CHO−. This same approach has been employed to indicate that 19 other anions may possess electronically excited states, five of which are valence in nature. Concurrently, in order to assist in the detection of these anions in the ISM, work has also been directed towards predicting vibrational frequencies and spectroscopic constants for these anions through the use of quartic force fields (QFFs). Theoretical rovibrational work on anions has thus far included studies of CH2CN−, C3H−, and is currently ongoing for similar systems.

GROUND AND EXCITED STATE PHOTOLUMINESCENCE MAPPING ON InAs/InGaAs QUANTUM DOT STRUCTURES

2007 ◽  
Vol 06 (05) ◽  
pp. 383-387
Author(s):  
T. V. TORCHYNSKA ◽  
E. VELÁZQUEZ LOZADA ◽  
M. DYBIEC ◽  
S. OSTAPENKO ◽  
P. G. ELISEEV ◽  
...  
Keyword(s):  
Excited State ◽  
Quantum Dot ◽  
Excited States ◽  
Long Range ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Excited State Energy ◽  
Photoluminescence Study ◽  
Range Variation

This paper presents the photoluminescence study at 12 K and scanning photoluminescence spectroscopy investigation of the ground and excited states at 80 and 300 K on InAs QDs inserted in In 0.15 Ga 0.85 As / GaAs QW structures and created at different QD growth temperatures. It is shown that investigated structures are characterized by the long range variation of an average QD size in QD ensemble across the wafer. This long range QD size inhomogeneity was used for investigation of the multi-excited state energy trend versus ground state energy (or QD sizes).

scholarly journals Cyclometalated Iridium-Coumarin Ratiometric Oxygen Sensors: Improved Signal Resolution and Tunable Dynamic Ranges

2021 ◽  
Author(s):  
Yanyu Wu ◽  
Gregory D. Sutton ◽  
Michael D. S. Halamicek ◽  
Thomas S. Teets
Keyword(s):  
Excited State ◽  
Excited States ◽  
State Energy ◽  
Dynamic Range ◽  
Oxygen Sensors ◽  
Oxygen Quenching ◽  
Dual Emission ◽  
Excited State Energy ◽  
Wide Range ◽  
Good Signal

In this work we introduce a new series of ratiometric oxygen sensors for hypoxic environments based on phosphorescent cyclometalated iridium centers partnered with organic coumarin fluorophores. Three different cyclometalating ligands and two different pyridyl-containing coumarin types were used to prepare six target complexes with tunable excited-state energies. Some of the complexes exhibit only phosphorescence originating from the cyclometalated Ir moiety, as a result of excited-state energy transfer from the coumarin to the Ir-centered excited states. Three of the complexes display dual emission, with fluorescence arising from the coumarin ligands and phosphorescence from the cyclometalated iridium synthons, and hence function as ratiometric oxygen sensors. Oxygen quenching experiments with these complexes demonstrate that the iridium centered phosphorescence is quenched under O₂ while fluorescence is unaffected. These sensors have good signal resolution, and the sensitivity and dynamic range, measured with Stern-Volmer analysis, span two orders of magnitude. This work demonstrates that this simple, modular approach for conjoining fluorescent and phosphorescent molecules can produce effective oxygen sensors with a wide range of attributes.

scholarly journals Excited State Character of Cibalackrot-Type Compounds Interpreted in Terms of Hückel-Aromaticity: A Rational for Singlet Fission Chromophore Design

2021 ◽  
Author(s):  
Weixuan Zeng ◽  
Ouissam El Bakouri ◽  
Dariusz Szczepanik ◽  
Hugo Bronstein ◽  
Henrik Ottosson
Keyword(s):  
Excited State ◽  
Theoretical Analysis ◽  
Excited States ◽  
State Energy ◽  
Energy Levels ◽  
Singlet Fission ◽  
Excited State Energy ◽  
Organic Chromophores ◽  
Spin Populations ◽  
Triplet Excited States

The exact energies of the lowest singlet and triplet excited states in organic chromophores are crucial to their performance in optoelectronic devices. The possibility of utilizing singlet fission to enhance the performance of photovoltaic devices has resulted in a wide demand for tuneable, stable organic chromophores with wide S<sub>1</sub> – T<sub>1</sub> energy gaps (>1 eV). Cibalackrot-type compounds were recently considered to have favorably positioned excited state energies for singlet fission, and they were found to have a degree of aromaticity in the lowest triplet excited state (T<sub>1</sub>). This work reports on a revised and deepened theoretical analysis taking into account the excited state Hückel-aromatic (instead of Baird-aromatic) as well as diradical characters, with the aim to design new organic chromophores based on this scaffold in a rational way starting from qualitative theory. We demonstrate that the substituent strategy can effectively adjust the spin populations on the chromophore moieties and thereby manipulate the excited state energy levels. Additionally, the improved understanding of the aromatic characters enables us to demonstrate a feasible design strategy to vary the excited state energy levels by tuning the number and nature of Hückel-aromatic units in the excited state. Finally, our study elucidates the complications and pitfalls of the excited state aromaticity and antiaromaticity concepts, highlighting that quantitative results from quantum chemical calculations of various aromaticity indices must be linked with qualitative theoretical analysis of the character of the excited states.

scholarly journals Picosecond Transient Raman Spectra of S1 Bis(Methylstyryl)- Benzene: Observation of S1←SnResonance Emission

1999 ◽  
Vol 19 (1-4) ◽  
pp. 381-384
Author(s):  
Terry L. Gustafson ◽  
James D. Leonard
Keyword(s):  
Excited State ◽  
Excited States ◽  
Broad Band ◽  
Energy Shift ◽  
Model System ◽  
State Structure ◽  
Electronically Excited States ◽  
Constant Energy ◽  
Resonance Emission ◽  
Electronically Excited

We have been studying the excited state spectra of several molecules related to electroluminescent conducting polymers. The excited state structure corresponds to the conducting state in these systems. We have obtained data on 1,4-bis(2,2′-methylstyryl)- benzene (2MSB) as a model system of poly (P-phenylenevinylene) (PPV). We observe both sharp and broad features in the spectra. The sharp bands occur at a constant energy shift relative to the probe wavelength. We attribute the sharp bands to resonance Raman bands of the S1 state of 2MSB. We assign the broad band at ∼740 nm to resonance emission between Sn and S1. We believe that this is the first observation of resonance secondary radiation (RSR) between two electronically excited states in a large molecule.

Cyclometalated Iridium-Coumarin Ratiometric Oxygen Sensors: Improved Signal Resolution and Tunable Dynamic Ranges

2021 ◽  
Author(s):  
Yanyu Wu ◽  
Gregory D. Sutton ◽  
Michael D. S. Halamicek ◽  
Thomas S. Teets
Keyword(s):  
Excited State ◽  
Excited States ◽  
State Energy ◽  
Dynamic Range ◽  
Oxygen Sensors ◽  
Oxygen Quenching ◽  
Dual Emission ◽  
Excited State Energy ◽  
Wide Range ◽  
Good Signal

In this work we introduce a new series of ratiometric oxygen sensors for hypoxic environments based on phosphorescent cyclometalated iridium centers partnered with organic coumarin fluorophores. Three different cyclometalating ligands and two different pyridyl-containing coumarin types were used to prepare six target complexes with tunable excited-state energies. Some of the complexes exhibit only phosphorescence originating from the cyclometalated Ir moiety, as a result of excited-state energy transfer from the coumarin to the Ir-centered excited states. Three of the complexes display dual emission, with fluorescence arising from the coumarin ligands and phosphorescence from the cyclometalated iridium synthons, and hence function as ratiometric oxygen sensors. Oxygen quenching experiments on these complexes demonstrate that the iridium centered phosphorescence is quenched under O₂ while fluorescence is unaffected. These sensors have good signal resolution, and the sensitivity and dynamic range, measured with Stern-Volmer analysis, span two orders of magnitude. This work demonstrates that this simple, modular approach for conjoining fluorescent and phosphorescent molecules can produce effective oxygen sensors with a wide range of attributes.

scholarly journals Excited State Character of Cibalackrot-Type Compounds Interpreted in Terms of Hückel-Aromaticity: A Rational for Singlet Fission Chromophore Design

2021 ◽  
Author(s):  
Weixuan Zeng ◽  
Ouissam El Bakouri ◽  
Dariusz Szczepanik ◽  
Hugo Bronstein ◽  
Henrik Ottosson
Keyword(s):  
Excited State ◽  
Theoretical Analysis ◽  
Excited States ◽  
State Energy ◽  
Energy Levels ◽  
Singlet Fission ◽  
Excited State Energy ◽  
Organic Chromophores ◽  
Spin Populations ◽  
Triplet Excited States

The exact energies of the lowest singlet and triplet excited states in organic chromophores are crucial to their performance in optoelectronic devices. The possibility of utilizing singlet fission to enhance the performance of photovoltaic devices has resulted in a wide demand for tuneable, stable organic chromophores with wide S<sub>1</sub> – T<sub>1</sub> energy gaps (>1 eV). Cibalackrot-type compounds were recently considered to have favorably positioned excited state energies for singlet fission, and they were found to have a degree of aromaticity in the lowest triplet excited state (T<sub>1</sub>). This work reports on a revised and deepened theoretical analysis taking into account the excited state Hückel-aromatic (instead of Baird-aromatic) as well as diradical characters, with the aim to design new organic chromophores based on this scaffold in a rational way starting from qualitative theory. We demonstrate that the substituent strategy can effectively adjust the spin populations on the chromophore moieties and thereby manipulate the excited state energy levels. Additionally, the improved understanding of the aromatic characters enables us to demonstrate a feasible design strategy to vary the excited state energy levels by tuning the number and nature of Hückel-aromatic units in the excited state. Finally, our study elucidates the complications and pitfalls of the excited state aromaticity and antiaromaticity concepts, highlighting that quantitative results from quantum chemical calculations of various aromaticity indices must be linked with qualitative theoretical analysis of the character of the excited states.

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