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SUMMARY:1D\, 2D\, 3D Perovskites and perovskitoids: structure diversity an
 d applications
DTSTART:20190510T103000
DTEND:20190510T113000
DTSTAMP:20260928T191523Z
UID:3eb836b9c8c5265a8a5e97f068ab294bb9772433c3dedf55d279984f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Mercouri G. Kanatzidis\,\nDpt of Chemistry\,\nNorthweste
 rn University\,\nEvantson\, USA\n \nThree-(3D) and two-dimensional (2D) l
 ayered halide perovskites are highly promising semiconductors for optoelec
 tronic applications ranging from solar cells\, light emitting diodes\, sof
 t radiation detector\, hard radiation detectors\, etc. The 3D versions of 
 these compounds adopt the three-dimensional ABX3 perovskite structure\, wh
 ich consists of a network of corner-sharing BX6 octahedra\, where the B at
 om is a divalent metal cation (typically Ge2+\, Sn2+ or Pb2+) and X is a m
 onovalent anion (typically Cl−\, Br−\, I−)\; the A cation is selecte
 d to balance the total charge and it can be a Cs+ or a small molecular spe
 cies. Another class of materials gaining significance are the two-dimensio
 nal (2D) perovskites -a blend of perovskites with layered crystal structur
 e- (Ruddlesden-Popper type) offer a greater synthetic versatility and allo
 w for more specialized device implementation due to the directional nature
  of the crystal structure. A remarkable advantage of the 2D perovskites is
  the readily tunable functionality by incorporating a wide array of organi
 c cations into the 2D framework and by controlling the slab thickness\, in
  contrast to the 3D analogues which have limited scope for structural engi
 neering. We present the new homologous series\, (C(NH2)3)(CH3NH3)nPbnI3n+1
  (n = 1\, 2\, 3)\, of layered 2D perovskites which is different from Ruddl
 esden-Popper type. These compounds adopt an unprecedented structure type w
 hich is stabilized by the alternating ordering of the guanidinium and meth
 ylammonium cations in the interlayer space (ACI). The these 2D perovskites
  combine structural characteristics from both Dion-Jacobson (DJ) and Ruddl
 esden-Popper (RP) structure archetypes. We also report the first examples 
 of hybrid DJ hybrid 2D lead iodide perovskites which consist of thick pero
 vskite slabs (n>1) with layer number (n) ranging from 1 to 5. We describe 
 two new DJ perovskite series based on bivalent (+2) spacer cations derivin
 g from a piperidinium (C5NH12) organic backbone. The new DJ perovskites ar
 e built from 3AMP (3AMP = 3-(aminomethyl)piperidinium) and 4AMP (4AMP =  
 4-(aminomethyl)piperidinium) spacers and methylammonium (MA) perovskitizer
 s cations to form A’(MA)n-1PbnI3n+1 (A’ = 3AMP or 4AMP\, n = 1-4) homo
 logous series acting as spacers. Surprisingly\, a slight difference in the
  position of the-CH2NH3+ group on the piperidine chair (3- and 4- position
  with respect to the piperidine nitrogen) exerts a strong influence on the
  crystal structure\, which is reflected on the distortion of the inorganic
  layers. This difference has a major impact on the optical and electronic 
 properties.\n 
LOCATION:I17 4 K2 https://plan.epfl.ch/?room==I17%204%20K2
STATUS:CONFIRMED
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