On Thursday, 20 February 2020 at 4:15 p.m. in Physicum lecture hall B103 (W. Ostwaldi 1, Tartu)
Mikhail G. Brik (UTIP Professor of Computer Modelling of Materials)
Red for LED
White light emitting diodes (LEDs) are widely used for both indoor and outdoor lighting applications. One of the main aims of research in this area is to produce white LEDs that mimic sunlight as closely as possible. Mixing emission of different colors is the way to get white light, but the main characteristics of the resultant emission depend crucially on properties of each component. For many years, white LEDs were composed of a blue GaN LED chip with yellow phosphor Y3Al5O12:Ce3+, that partially converts blue light into yellow. However, due to the lack of red light in this device, the produced white light is perceived to be a “cold” white light. Addition of a red phosphor to such LED can improve the emitted white light characteristics enormously.
In this presentation several basic approaches to get white light will be discussed, with highlighting their pros and cons. The role of different red phosphors in the white phosphor-converted LEDs for the lighting and agricultural applications will be shown, with several examples based on the original publications, e.g. [1-6].
The final part of the talk will be devoted to a short review of the book on spectroscopy of the transition metal and rare earth ions published recently .
Mikhail G. Brik received his PhD from Kuban State University (Russia) in 1995 and his DSc (habilitation) from the Institute of Physics, Polish Academy of Sciences (Poland) in 2012. Since 2007 he is a professor at the Institute of Physics, University of Tartu, Estonia. Before that, he worked at Kyoto University (Japan) from 2003 to 2007, Weizmann Institute of Science (Israel) in 2002, Asmara University (Eritrea) from 2000 to 2001, and Kuban State University from 1995 to 2000. He is also a distinguished visiting professor at Chongqing University of Posts and Telecommunications (China) and Professor at Jan Długosz University (Poland). Since 2015 he serves as one of the editors of Optical Materials (Elsevier). Prof. Brik’s scientific interests cover theoretical spectroscopy of transition metal and rare earth ions in optical materials, crystal field theory, and ab initio calculations of the physical properties of pure and doped functional compounds. He is a coeditor of two books and author of 12 book chapters and about 390 papers in international journals. According to Google Scholar (November 2019), he has more than 7500 citations with h index 41. He received the Dragomir Hurmuzescu Award of Romanian Academy in 2006 and the State Prize of the Republic of Estonia in the field of exact sciences in 2013. In 2018 he received the state professor title from the President of Poland.
 M.G. Brik, A.M. Srivastava, J. Lumin. 133 (2013) 69.
 M.G. Brik, S.J. Camardello, A.M. Srivastava, ECS J. Solid State Sci. & Technol. 4 (2015) R39.
 M.G. Brik, S.J. Camardello, A.M. Srivastava, N.M. Avram, A. Suchocki, ECS J. Solid State Sci. & Technol. 5 (2016) R3067.
 Q. Zhou, L. Dolgov, A.M. Srivastava, L. Zhou, Z.L. Wang, J.X. Shi, M.D. Dramićanin, M.G. Brik, M.M. Wu, J. Mater. Chem. C 6 (2018) 2652.
 A.M. Srivastava, M.G. Brik, H.A. Comanzo, W.W. Beers, W.E. Cohen, T. Pocock, ECS J. Solid State Sci. & Technol. 7 (2018) R3158.
 M.G. Brik, W.W. Beers, W. Cohen, S.A. Payne, N.J. Cherepy, M. Piasecki, A.M. Srivastava, Opt. Mater. 91 (2019) 338.
 M.G. Brik, C.-G. Ma, “Theoretical Spectroscopy of Transition Metal and Rare Earth Ions: From Free State to Crystal Field”, Jenny Stanford Publishing Pte. Ltd, Singapore, 2020, ISBN 978-981-4800-56-3, 460 p.
The Physicum seminars are meant for a broad auditorium of physicists and materials scientists, as well as for interested people from other natural and exact sciences (including bacheleor level students) and aim at introducing what is important and new in a certain field, or where a specific reasearch direction has reached today.
Everybody is welcome to attend.