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SUMMARY:Crystalline Covalent Organic Frameworks Designed for Optoelectroni
 c Applications - Dr Florian Auras\, Ludwig Maximilian University of Munich
DTSTART:20160210T130000Z
DTEND:20160210T140000Z
UID:TALK64393@talks.cam.ac.uk
CONTACT:Stuart Higgins
DESCRIPTION:Covalent organic frameworks (COFs) formed by connecting multid
 entate organic building blocks through covalent bonds provide a platform f
 or designing multifunctional porous materials with atomic precision. In pa
 rticular\, the integration of π-conjugated building blocks\, such as thio
 phenes or porphyrins\, into the networks enables the formation of structur
 ally defined organic semiconductors.\n\nWe have developed a synthetic conc
 ept to allow consecutive COF sheets to lock in position during crystal gro
 wth\, and thus minimize the occurrence of stacking faults and dislocations
 .[1] Hereby\, the three-dimensional conformation of propeller-shaped molec
 ular building units was used to generate well-defined periodic docking sit
 es\, which guided the attachment of successive building blocks that\, in t
 urn\, promoted long-range order during COF formation. This approach enable
 s us to achieve a very high crystallinity for a series of COFs that compri
 se tri- and tetradentate central building blocks. \n\nThe π-stacked colum
 ns of layered two-dimensional COFs enable electronic interactions between 
 the COF sheets\, thereby providing a path for exciton and charge carrier m
 igration (Figure 1).[2] Frameworks comprising two electronically separated
  subunits can form highly defined interdigitated donor−acceptor heteroju
 nctions\, which can drive the photogeneration of free charge carriers. We 
 have constructed a photovoltaic device that utilizes exclusively a crystal
 line organic framework with an inherent type II heterojunction as the acti
 ve layer. \n\nWe anticipate these concepts to be applicable to a broad var
 iety of functional building blocks and to promote the establishment of COF
 s in catalysis and organic electronics.\n\n[1]	L. Ascherl\, T. Sick\, J. T
 . Margraf\, S. H. Lapidus\, M. Calik\, C. Hettstedt\, K. Karaghiosoff\, M.
  Döblinger\, T. Clark\, K. W. Chapman\, F. Auras\, T. Bein\, Nature Chem.
  2016\, DOI 10.1038/NCHEM.2444.\n[2]	M. Calik\, F. Auras\, L. M. Salonen\,
  K. Bader\, I. Grill\, M. Handloser\, D. D. Medina\, M. Dogru\, F. Löberm
 ann\, D. Trauner\, A. Hartschuh\, T. Bein\, J. Am. Chem. Soc. 2014\, 136\,
  17802.\n
LOCATION:Kapitza Building Seminar Room\, Cavendish Laboratory\, Department
  of Physics
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