000223449 001__ 223449
000223449 005__ 20190509132603.0
000223449 0247_ $$2doi$$a10.5075/epfl-thesis-7091
000223449 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis7091-4
000223449 02471 $$2nebis$$a10788678
000223449 037__ $$aTHESIS
000223449 041__ $$aeng
000223449 088__ $$a7091
000223449 245__ $$bcrystals for novel electronics$$aSwitchable silver clusters
000223449 269__ $$a2016
000223449 260__ $$bEPFL$$c2016$$aLausanne
000223449 300__ $$a142
000223449 336__ $$aTheses
000223449 502__ $$aProf. Véronique Michaud (présidente) ; Prof. Francesco Stellacci (directeur de thèse) ; Prof. Dragan Damjanovic, Prof. Paolo Samorì, Prof. Thomas Buergi (rapporteurs)
000223449 520__ $$aMetallic nanoclusters form a family of novel materials with atomically defined hybrid organic/inorganic structures. Among these materials, clusters containing 44 silver atoms have emerged as one of the most interesting, because of their exceptional electronic and optical properties. Recently synthetic progresses made possible their crystallisation. Crystals of Ag44 clusters form what is defined as a superlattice, a periodic three dimensional structure, whose properties are expected to depend on the collective interaction of its constituents. In this thesis, clusters with a molecular formula Ag((SC6H4F)30)4-€“ have been crystallized in the presence of four tetraphenyl phosponium [(C6H5)4P+] counterions and the crystals have been fully characterized. The response of these crystals to an external electric field was then tested in a two- and four- terminal configuration, and showed conductivity switching at high voltages between a less and a more conductive phase. Single crystal X-ray diffraction measurements showed that each of the conductive phase was characterized by a different crystal structure, suggesting an electric-field induced phase transition. The change in properties is attributed to the collective displacement of the tetraphenyl phosphonium counterions, which causes a change in orientation of 3 of the 30 fluorophenyl thiols that coat the cluster. Overall all these local changes lead to a global redistribution of the charges in the crystal. To the best of my knowledge, this work presents the first experimental observation of the phenomenon due to a collective behavior in a crystal of nanoclusters as well as in a crystal with more than 1000 atoms in the unit cell.
000223449 6531_ $$ananocluster
000223449 6531_ $$aAg44
000223449 6531_ $$asuperlattice
000223449 6531_ $$acollective properties
000223449 6531_ $$athiol
000223449 6531_ $$aXRD
000223449 6531_ $$aphase transition
000223449 700__ $$0245756$$g217807$$aAllegri, Sergio
000223449 720_2 $$aStellacci, Francesco$$edir.$$g196998$$0244724
000223449 8564_ $$uhttps://infoscience.epfl.ch/record/223449/files/EPFL_TH7091.pdf$$zn/a$$s32735504$$yn/a
000223449 909C0 $$xU12173$$0252323$$pSUNMIL
000223449 909CO $$pthesis$$pthesis-bn2018$$pDOI$$ooai:infoscience.tind.io:223449$$qDOI2$$qGLOBAL_SET$$pSTI
000223449 917Z8 $$x108898
000223449 917Z8 $$x108898
000223449 918__ $$dEDMX$$cIMX$$aSTI
000223449 919__ $$aSUNMIL
000223449 920__ $$b2016$$a2016-12-9
000223449 970__ $$a7091/THESES
000223449 973__ $$sPUBLISHED$$aEPFL
000223449 980__ $$aTHESIS