"Thermally Activated Delayed Fluorescence. Phasor approaches to fluorescence"
Palestrante: Prof. Mário Berberan e Santos (Instituto Superior Técnico, Universidade de Lisboa, Portugal)
Dia: 05 de junho (segunda-feira), às 10h.
Local: IQUSP (Queijinho A5).
Sobre o palestrante:
O prof. Mario Berberan-Santos é professor/pesquisador do Instituto Superior Tecnico, Universidade de Lisboa, Portugal, especialista em fluorescência e nanosensores. Ele estará nos visitando dos dias 5 a 8 de Junho.
Os interessados em conversar com o prof. Berberan por favor enviem uma mensagem para a Dra. Helena Couto Junqueira, informando local/dia/horário (hcjunqueira@gmail.com).
Maiores informações também com:
Rosangela Itri - 91-7012; itri@if.usp.br
Abstract:
Two different fluorescence topics will be addressed in this presentation. The first, Thermally activated delayed fluorescence (TADF), concerns a special type of fluorescence. The second, the phasor approach (in fact, several related approaches), is a method of data analysis.
There was a recent surge of interest in Thermally Activated Delayed Fluorescence (TADF) owing to its application in 3rd generation Organic Light-Emitting Diodes (OLEDs) [1-3]. In this work, the kinetics of TADF is discussed, contrasting TADF in photoluminescence and TADF in electroluminescence [4,5]. Two different types of TADF are identified: One-way and two-way TADF. It is shown that for a given efficiency, one-way TADF allows lower rates of reverse intersystem crossing. Graphical and quantitative indicators of singlet-triplet interconversion and photophysical efficiency are obtained and applied to the photoluminescence of several compounds and to the electroluminescence of TADF emitters specifically designed for OLEDs. Applications of TADF in temperature and oxygen sensing will be mentioned.
Phasor plots [6-8] (plots of the Fourier sine transform vs. the Fourier cosine transform, for one or several angular frequencies) of both the fluorescence intensity decay and of the fluorescence spectrum (spectral phasor plot) are being increasingly used in studies of homogeneous and heterogeneous systems. In this presentation, the phasor approach to fluorescence decays [9] is presented and applied to monomer-excimer [10] and TADF (thermally activated delayed fluorescence) systems. Spectral phasors [11] are discussed in the contexts of monomer-excimer analysis and fluorescence microscopy and compared with recently developed alternative methods.
[1] Tao, Y.; Yuan, K.; Chen, T.; Xu, P.; Li, H.; Chen, R.; Zheng, C.; Zhang, L.; Huang, W. Thermally Activated Delayed Fluorescence Materials Towards the Breakthrough of Organoelectronics. Adv. Mater. 2014, 26, 7931-7958.
[2] Shizu, K.; Lee, J.; Tanaka, H.; Nomura, H.; Yasuda, T.; Kaji, H.; Adachi, C. Highly Efficient Electroluminescence from Purely Organic Donor-Acceptor Systems. Pure Appl. Chem. 2015, 87, 627-638.
[3] Bergmann, L.; Zink, D. M.; Bräse, S.; Baumann, T.; Volz, D. Metal-Organic and Organic TADF-Materials: Status, Challenges and Characterization. Top. Curr. Chem (Z) 2016, 374:22.
[4] Dias, F. B.; Santos, J.; Graves, D. R.; Data, P.; Nobuyasu, R. S.; Fox, M. A.; Batsanov, A. S.; Palmeira,T.; Berberan-Santos, M. N.; Bryce, M. R.; Monkman, A. P., The Role of Local Triplet Excited States and D-A Relative Orientation in Thermally Activated Delayed Fluorescence: Photophysics and Devices, Adv. Sci. 2016, 1600080.
[5] Palmeira, T; Berberan-Santos, M. N. Kinetic criteria for optimal thermally activated delayed fluorescence (TADF) in photoluminescence and in electroluminescence, J. Phys. Chem. C 2017, 121, 701-708.
[6] B. Valeur and M. N. Berberan-Santos, Molecular Fluorescence. Principles and
Applications, Wiley-VCH, Weinheim, 2nd ed., 2012.
[7] D. M. Jameson, Introduction to Fluorescence, CRC Press, Boca Raton, 2014.
[8] Y. Engelborghs, A. J. W. G. Visser eds., Fluorescence Spectroscopy and Microscopy, Humana Press, New York, 2014.
[9] M. N. Berberan-Santos. Chem. Phys. 449 (2015) 23-33.
[10] L. Martelo, A. Fedorov, M. N. Berberan-Santos, J. Phys. Chem. B 119 (2015) 15023-15029.
[11] F. Fereidouni, A. N. Bader, H. C. Gerritsen, Opt. Express 20 (2012) 12729-12741.
Término:
05/06/2017
