Spectral ? Kinetic properties of the delayed fluorescence of complex molecules with inhomogeneously broadened energy levels

1982 ◽  
Vol 37 (1) ◽  
pp. 804-808 ◽  
Author(s):  
S. K. Gorbatsevich ◽  
I. M. Gulis ◽  
A. I. Komyak ◽  
Yu. I. Miksyuk
Keyword(s):  
Energy Levels ◽  
Delayed Fluorescence ◽  
Kinetic Properties ◽  
Complex Molecules

scholarly journals The ALMA-PILS Survey: Formaldehyde deuteration in warm gas on small scales toward IRAS 16293–2422 B

2018 ◽  
Vol 610 ◽  
pp. A54 ◽  
Author(s):  
M. V. Persson ◽  
J. K. Jørgensen ◽  
H. S. P. Müller ◽  
A. Coutens ◽  
E. F. van Dishoeck ◽  
...  
Keyword(s):  
Energy Levels ◽  
Excitation Temperature ◽  
Thermodynamical Equilibrium ◽  
Complex Molecules ◽  
Important Species ◽  
Chemical Models ◽  
Small Scales ◽  
Core Phase ◽  
Low Mass ◽  
First Time

Context.The enhanced degrees of deuterium fractionation observed in envelopes around protostars demonstrate the importance of chemistry at low temperatures, relevant in pre- and protostellar cores. Formaldehyde is an important species in the formation of methanol and more complex molecules.Aims.Here, we aim to present the first study of formaldehyde deuteration on small scales around the prototypical low-mass protostar IRAS 16293–2422 using high spatial and spectral resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations. We determine the excitation temperature, abundances and fractionation level of several formaldehyde isotopologues, including its deuterated forms.Methods.Excitation temperature and column densities of formaldehyde in the gas close to one of the components of the binary were constrained through modeling of optically thin lines assuming local thermodynamical equilibrium. The abundance ratios were compared to results from previous single dish observations, astrochemical models and local ISM values.Results.Numerous isotopologues of formaldehyde are detected, among them H2C17O, and D213CO for the first time in the ISM. The large range of upper energy levels covered by the HDCO lines help constrain the excitation temperature to 106 ± 13 K. Using the derived column densities, formaldehyde shows a deuterium fractionation of HDCO/H2CO = 6.5 ± 1%, D2CO/HDCO = 12.8–4.1+3.3%, and D2CO/H2CO = 0.6(4) ± 0.1%. The isotopic ratios derived are16O/18O = 805–79+43,18O/17O = 3.2–0.3+0.2, and12C/13C = 56–11+8.Conclusions.The HDCO/H2CO ratio is lower than that found in previous studies, highlighting the uncertainties involved in interpreting single dish observations of the inner warm regions. The D2CO/HDCO ratio is only slightly larger than the HDCO/H2CO ratio. This is consistent with formaldehyde forming in the ice as soon as CO has frozen onto the grains, with most of the deuteration happening toward the end of the prestellar core phase. A comparison with available time-dependent chemical models indicates that the source is in the early Class 0 stage.

scholarly journals Purely Organic Phosphor Sensitization Based Highly Efficient Electrofluorescence Material

2021 ◽  
Author(s):  
Jiaxuan Wang ◽  
Baoyan Liang ◽  
Jinbei Wei ◽  
Yincai Xu ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Light Emission ◽  
Internal Quantum Efficiency ◽  
Energy Levels ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Carrier Injection ◽  
Light Emitting Devices ◽  
Highly Efficient ◽  
New Strategy

Pure organic room temperature phosphorescence (RTP) materials are considered as potential candidates for replacing precious metal-based complexes to fabricate highly efficient organic light emitting devices (OLEDs). However, for reported RTP materials, low photoluminescence quantum yields (PLQYs) in thin film state seriously impede their applications in OLEDs. On the other hand, how using normal organic fluorescence materials to fabricate OLEDs with an internal quantum efficiency (IQE) over 25% remains a great unaddressed issue beyond the thermally activated delayed fluorescence (TADF) sensitization approach. Here, we establish a strategy to construct highly efficient OLEDs based on pure organic RTP material sensitized fluorescence emitter. The key point for our strategy is that benzimidazole-triazine molecules (PIM-TRZ), 2,6-di(phenothiazinyl)naphthalene (β-DPTZN) and 5,6,11,12-tetraphenylnaphthacene (rubrene) were screened as host, phosphor sensitizer and fluorescent emitter, respectively. Detail photophysical characterizations demonstrate that the host material PIMTRZ with unique RTP nature is critical for achieving phosphor sensitizing process. As an organic RTP compound, the singlet and triplet state energy levels of β-DPTZN perfectly match with those of PIMTRZ, resulting in the formation and lasting existence of phosphor’s excitons in emitting layer. The large overlap between the absorption spectrum of rubrene and PL spectrum of PIM-TRZ:10% β-DPTZN film can facilitate the Förster energy transfer from the triplet β-DPTZN to the singlet rubrene and the finally displayed fluorescence is derived from singlet excited states of rubrene. The perfect collocation of host, phosphorescent sensitizer and fluorescent emitter in the emitting layer promise the predominant performance of the devices with external quantum efficiency (EQE) of 15.7%. The PLQY of emitting layer is 60.3%, and therefore about 90% carrier injection induced excitons are harvested for light emission. We present a new strategy to fabricate efficient fluorescent devices by employing ingenious combination of host, phosphorescent sensitizer and fluorescent emitter, which is significant to the development of OLEDs.<br>

scholarly journals Purely Organic Phosphor Sensitization Based Highly Efficient Electrofluorescence Material

2021 ◽  
Author(s):  
Jiaxuan Wang ◽  
Baoyan Liang ◽  
Jinbei Wei ◽  
Yincai Xu ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Light Emission ◽  
Internal Quantum Efficiency ◽  
Energy Levels ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Carrier Injection ◽  
Light Emitting Devices ◽  
Highly Efficient ◽  
New Strategy

Pure organic room temperature phosphorescence (RTP) materials are considered as potential candidates for replacing precious metal-based complexes to fabricate highly efficient organic light emitting devices (OLEDs). However, for reported RTP materials, low photoluminescence quantum yields (PLQYs) in thin film state seriously impede their applications in OLEDs. On the other hand, how using normal organic fluorescence materials to fabricate OLEDs with an internal quantum efficiency (IQE) over 25% remains a great unaddressed issue beyond the thermally activated delayed fluorescence (TADF) sensitization approach. Here, we establish a strategy to construct highly efficient OLEDs based on pure organic RTP material sensitized fluorescence emitter. The key point for our strategy is that benzimidazole-triazine molecules (PIM-TRZ), 2,6-di(phenothiazinyl)naphthalene (β-DPTZN) and 5,6,11,12-tetraphenylnaphthacene (rubrene) were screened as host, phosphor sensitizer and fluorescent emitter, respectively. Detail photophysical characterizations demonstrate that the host material PIMTRZ with unique RTP nature is critical for achieving phosphor sensitizing process. As an organic RTP compound, the singlet and triplet state energy levels of β-DPTZN perfectly match with those of PIMTRZ, resulting in the formation and lasting existence of phosphor’s excitons in emitting layer. The large overlap between the absorption spectrum of rubrene and PL spectrum of PIM-TRZ:10% β-DPTZN film can facilitate the Förster energy transfer from the triplet β-DPTZN to the singlet rubrene and the finally displayed fluorescence is derived from singlet excited states of rubrene. The perfect collocation of host, phosphorescent sensitizer and fluorescent emitter in the emitting layer promise the predominant performance of the devices with external quantum efficiency (EQE) of 15.7%. The PLQY of emitting layer is 60.3%, and therefore about 90% carrier injection induced excitons are harvested for light emission. We present a new strategy to fabricate efficient fluorescent devices by employing ingenious combination of host, phosphorescent sensitizer and fluorescent emitter, which is significant to the development of OLEDs.<br>

Line-narrowed spectra and kinetics of laser-excited delayed fluorescence of complex molecules in solid solutions

1988 ◽  
Vol 128 (1) ◽  
pp. 9-21 ◽  
Author(s):  
N.A. Efremov ◽  
S.G. Kulikov ◽  
R.I. Personov ◽  
Yu.V. Romanovskii
Keyword(s):  
Solid Solutions ◽  
Delayed Fluorescence ◽  
Complex Molecules ◽  
Kinetics Of

Design principles of carbazole/dibenzothiophene derivatives as host material in modern efficient organic light-emitting diodes

2017 ◽  
Vol 5 (28) ◽  
pp. 6989-6996 ◽  
Author(s):  
Junming Li ◽  
Shou-Cheng Dong ◽  
Andreas Opitz ◽  
Liang-Sheng Liao ◽  
Norbert Koch
Keyword(s):  
Carrier Transport ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Photophysical Properties ◽  
Energy Levels ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Host Materials

Host materials for modern high-efficiency organic light-emitting diodes (OLEDs) based on phosphorescence and thermally activated delayed fluorescence were optimized with respect to thermal stability, photophysical properties, energy levels, and charge carrier transport.

scholarly journals Methanol formation in TW Hya and future prospects for detecting larger complex molecules in disks with ALMA

2017 ◽  
Vol 13 (S332) ◽  
pp. 395-402 ◽  
Author(s):  
Catherine Walsh ◽  
Shreyas Vissapragada ◽  
Harry McGee
Keyword(s):  
Gas Phase ◽  
Signal To Noise Ratio ◽  
Energy Levels ◽  
Complex Molecules ◽  
Rotational Spectra ◽  
Chemical Models ◽  
Methanol Formation ◽  
Peak Abundance ◽  
Abundance And Distribution ◽  
First Time

AbstractGas-phase methanol was recently detected in a protoplanetary disk for the first time with ALMA. The peak abundance and distribution of methanol observed in TW Hya differed from that predicted by chemical models. Here, the chemistry of methanol gas and ice is calculated using a physical model tailored for TW Hya with the aim to contrast the results with the recent detection in this source. New pathways for the formation of larger complex molecules (e.g., ethylene glycol) are included in an updated chemical model, as well as the fragmentation of methanol ice upon photodesorption. It is found that including fragmentation upon photodesorption improves the agreement between the peak abundance reached in the chemical models with that observed in TW Hya (∼10−11 with respect to H2); however, the model predicts that the peak in emission resides a factor of 2 − 3 farther out in the disk than the ALMA images. Reasons for the persistent differences in the gas-phase methanol distribution between models and the observations of TW Hya are discussed. These include the location of the ice reservoir which may coincide with the compact mm-dust disk (≲ 60 au) and sources of gas-phase methanol which have not yet been considered in models. The possibility of detecting larger molecules with ALMA is also explored. Calculations of the rotational spectra of complex molecules other than methanol using a parametric model constrained by the TW Hya observations suggest that the detection of individual emission lines of complex molecules with ALMA remains challenging. However, the signal-to-noise ratio can be enhanced via stacking of multiple transitions which have similar upper energy levels.

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