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SEMINAR:Efficient Diffusion of Excitons in Lead Halide Perovskites

Speaker:  R. Tuğrul Senger, Department of Physics, İzmir Institute of Technology

Title:  Efficient Diffusion of Excitons in Lead Halide Perovskites

Date/Time:04 January 2023 / 13:40 - 14:30

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Abstract:Hybrid organic–inorganic lead halide perovskites have promising properties for photovoltaic and optoelectronic applications. We investigate temperature-dependent photogenerated- carrier-diffusion in single-crystal methylammonium lead iodide/bromide (MAPbI3 and MAPbBr3) microstructures via scanning photocurrent microscopy. We measure abrupt increases in carrier diffusion lengths across the tetragonal to orthorhombic phase transitions of the crystals, reaching 200±50 μm at 80 K for MAPbI3. We attribute this finding to the formation and efficient transport of free excitons in the orthorhombic phase. We discuss polaronic effects on the formation of excitons in these ionic materials.

Bio: Tuğrul Senger was born in 1971 in Akhisar, Manisa, Turkey. After graduating from Bornova Anadolu Lisesi and İzmir Fen Lisesi, in 1989 he was admitted to Bilkent University EE department, ranking 12th in the university entrance exam nationwide. Changing his major, he received his B.S. (1994), M.S. (1996), and Ph. D. (2000) degrees in Physics from Bilkent University. He was an instructor at Bilkent for a year, and a Postdoctoral Research Fellow at Emory University, Atlanta, USA during 2001-2003. Dr. Senger worked at TÜBİTAK-UEKAE as a Senior Researcher until he has joined Bilkent University in September 2004 as Assistant Professor of Physics. In January 2009 he has moved to İzmir Institute of Technology (İYTE) as an Associate Professor. Currently, he is a full Professor at İYTE since October 2011. He served at various İYTE administrative positions, including Dean of the Graduate School, Senate Member, Chair of the Physics Department. His Ph. D. research focused on electron-phonon interactions in low-dimensional systems, and theory of polarons and bipolarons. He studied on excitonic properties of highly ionic compounds and heterostructures during his postdoctoral fellowship. His current research interests include computational materials science, quantum transport in nanostructures, and spintronics. He has authored more than 70 articles in peer reviewed journals. Dr. Senger received undergraduate scholarships from Bilkent University, TÜBİTAK and VAKSA, and graduate fellowship from Münir Birsel Foundation. He received 2006 "Young Investigator Award (GEBİP)" of Turkish Academy of Sciences (TÜBA), 2009 "Young Scientist Award" of FABED, and 2010 "Research Incentive Award" of ODTÜ Parlar Foundation. He is a member of The Science Academy, Turkey (Bilim Akademisi).