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41.
热激活延迟荧光(Thermally activated delayed fluorescence, TADF)材料由于三线态激子可通过反系间窜越(Reverse intersystem crossing, RISC)转换为单线态激子,在有机发光二极管(Organic light-emitting diodes, OLEDs)中理论上可达到100%的激子利用率而被广泛关注。但实验上开发设计高性能TADF材料较为复杂且研究周期较长,理论研究可以从本质上建立材料结构-性能的关系,预测材料的性质并提供一定的分子设计策略。本文围绕高性能TADF材料的开发,从发光原理出发,系统阐述了分子的设计策略及光物理参数如材料单-三线态能级差(Single-triplet energy gap,ΔEST)、系间/反系间窜越速率、吸收/发射光谱、辐射/非辐射速率等的计算原理、计算方法和研究进展。最后我们探讨了TADF材料理论研究面临的机遇和挑战,通过对TADF材料的理论研究综述和研究前景的展望,期待吸引更多的研究工作者,推动该领域的发展和突破。 相似文献
42.
Thermally Activated Delayed Fluorescence in a Y3N@C80 Endohedral Fullerene: Time‐Resolved Luminescence and EPR Studies 下载免费PDF全文
Dr. Michal Zalibera Denis S. Krylov Dimitrios Karagiannis Paul‐Anton Will Frank Ziegs Sandra Schiemenz Prof. Dr. Wolfgang Lubitz Prof. Dr. Sebastian Reineke Dr. Anton Savitsky Dr. Alexey A. Popov 《Angewandte Chemie (International ed. in English)》2018,57(1):277-281
The endohedral fullerene Y3N@C80 exhibits luminescence with reasonable quantum yield and extraordinary long lifetime. By variable‐temperature steady‐state and time‐resolved luminescence spectroscopy, it is demonstrated that above 60 K the Y3N@C80 exhibits thermally activated delayed fluorescence with maximum emission at 120 K and a negligible prompt fluorescence. Below 60 K, a phosphorescence with a lifetime of 192±1 ms is observed. Spin distribution and dynamics in the triplet excited state is investigated with X‐ and W‐band EPR and ENDOR spectroscopies and DFT computations. Finally, electroluminescence of the Y3N@C80/PFO film is demonstrated opening the possibility for red‐emitting fullerene‐based organic light‐emitting diodes (OLEDs). 相似文献
43.
具有热活化延迟荧光(thermally activated delayed fluorescence, TADF)特性的配合物可以同时利用单重态和三重态激子,因此发光量子效率较高,近年来受到广大科研工作者的关注。特别是铜金属有机配合物,最低单重态和最低三重态的能量差较小,又可以通过不同配体或取代基进行调节,所以具有较好TADF性能。本文根据配位原子的类型,汇总和分析了近5年具有TADF性质的铜配合物的结构特点和发光性能,并简要讨论了其在有机发光二极管(organic light-emitting diodes,OLEDs)中的潜在应用。 相似文献
44.
混沌系统延迟反馈控制的理论与实验研究 总被引:19,自引:0,他引:19
综述了近年来控制混沌的延迟反馈控制技术------DFC控制的相关进展,总结了延迟反馈控制在不动点和不稳定周期轨道镇定方面的局限性和可控性研究的理论成果,介绍了延迟反馈控制在电子线路和磁弹性梁混沌控制方面的实验,并对延迟反馈控制技术未来的研究方向和发展前景进行了预测和展望。 相似文献
45.
This paper investigates the exact and approximate spectrum assignment properties associated with realizable output-feedback pole-placement type controllers for single-input single-output linear time-invariant time-delay systems with commensurate point delays. The controller synthesis problem is discussed through the solvability of a set of coupled diophantine equations of polynomials. An extra complexity is incorporated to the above design to cancel extra unsuitable dynamics being generated when solving the above diophantine equations. Thus, the complete controller tracks any arbitrary prefixed (either finite or delaydependent) closed-loop spectrum. However, if the controller is simplified by deleting the above mentioned extra complexity, then the robust stability and approximated spectrum assignment are still achievable for a certain sufficiently small amount of delayed dynamics. Finally, the approximate spectrum assignment and robust stability problems are revisited under plant disturbances if the nominal controller is maintained. In the current approach, the finite spectrum assignment is only considered as a particular case to the designer‘s choice of a (delay-dependent) arbitrary spectrum assignment objective. 相似文献
46.
Let M
n
denote the partial maximum of a strictly stationary sequence (X
n
). Suppose that some of the random variables of (X
n
) can be observed and let [(M)\tilde]n\tilde M_n
stand for the maximum of observed random variables from the set {X
1, ..., X
n
}. In this paper, the almost sure limit theorems related to random vector ([(M)\tilde]n\tilde M_n
, M
n
) are considered in terms of i.i.d. case. The related results are also extended to weakly dependent stationary Gaussian sequence as its covariance function satisfies
some regular conditions. 相似文献
47.
This paper investigates the dynamical behaviour of the Liu system with time delayed feedback. Two typical situations are considered and the effect of time-delay parameter on the dynamics of the system is discussed. It is shown that the Liu system with time delayed feedback may exhibit interesting and extremely rich dynamical behaviour. The evolution of the dynamics is shown to be complex with varying time-delay parameter. Moreover, the strange attractor like ‘wormhole' is detected via numerical simulations. 相似文献
48.
孙元功 《纯粹数学与应用数学》2002,18(2):170-173
对于一类特殊的具有时滞的二阶次线性强迫微分方程x"(t) +a (t)|x(τ(t))|γsgnx(τ(t)) =g(t)(0<τ<1),给出了它的所有解振动的一个充要条件. 相似文献
49.
M. E. Bashtanov N. N. Drozdova A. A. Krasnovskii 《Journal of Applied Spectroscopy》1999,66(4):550-555
The relative intensity of photosensitized phosphorescence of singlet oxygen (1O2) at 1270 nm (L1270) and1O2-induced delayed fluorescence (Ldf) of bacteriopheophytin a (BPh) (770 nm) in air-saturated solutions of BPh in hexafluorobenzene in excitation by 337-nm pulses
of a nitrogen laso is investigated. It is established that Ldf≪L1270. The ratio of the initial intensity of delayed fluorescence and phosphorescence of1O2(Ldf)0/(L1270)0 changed from 0.02 to 0.30 as a function of the energies of laser pulses (2.5–5.0 mJ/cm1) and the BPh concentration (6–18 μM). As the index of quantum efficiency of the delayed fluorescence, the authors used the
coefficient
where [1O2]0 is the initial concentration of1O2 after the laser burst; [Bpn] is the concentration of BPh; kr is the constant of the rate of1O2 radiative deactivation in the solvent under study; γf is the quantum yield of BPh fluorescence. It is established that this
coefficient is smaller by a factor of ∼2000 than in phthalocyanine, while its absolute value is ∼2·1010M−2sec−1. The saturation of BPh solutions with oxygen at atmospheric pressure is shown to lead to a fivefold attenuation of the delayed
fluorescence as compared to air-saturated solutions. The possibility of BPh triplet molecules being involved in the radiation
of delayed fluorescence of the pigment is discussed.
Reported at the VIIIth International Conference on Spectroscopy of Porphyrins and Their Analogs, Minsk, September 22–26, 1998.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 504–508, July–August, 1999. 相似文献
50.
E. Amaldi E. Coccia C. Cosmelli Y. Ogawa G. Pizzella P. Rapagnani F. Ricci P. Bonifazi M. G. Castellano G. Vannaroni F. Bronzini P. Carelli V. Foglietti G. Cavallari R. Habel I. Modena G. V. Pallottino 《Il Nuovo Cimento C》1984,7(3):338-354
Summary We report on the cooling at liquid-helium temperature of our 2270 kg 5056 Al bar at CERN. The liquid-helium container had
been filled up to 1500 liters ensuring to keep the antenna cold for more than one month. The antenna is equipped with a resonant
capacitive transducer operating at constant electrical charge with a FET low-noise amplifier. The transducer is tuned to the
antenna within less than I Hz and the two normal-mode frequencies are ν−=908.160 Hz and ν+=924.234 Hz with an applied electrical field in the transducer of 106 V/m. The corresponding overall merit factors areQ
−=5.20·106 andQ
+=7.25·106. The transducer has been tested up to an electrical field of 6·106 V/m: in this condition we have βQ≈104. The antenna has been in operation for several weeks giving, for the Brownian noise, values in agreement with the calculated
values. We report also on the results of tests performed on a DC SQUID, whose input was connected to a commercial capacitor
via a transformer with turn ratio of 1000.
Supported in part by Japan Society for the Promotion of Science. 相似文献