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SUMMARY:Amazing 3D and 2D Halide Perovskites: All the things they do
DTSTART:20190509T161500
DTEND:20190509T171500
DTSTAMP:20260506T144550Z
UID:2f97da17e843ad4fa48df8afde0ae42bce3e9df934a39894b6ce44f3
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Mercouri G. Kanatzidis\,\nDpt of Chemistry\,\nNorthweste
 rn University\,\nEvantson\, USA\nThree-(3D) and two-dimensional (2D) layer
 ed halide perovskites are highly promising semiconductors for optoelectron
 ic applications ranging from solar cells\, light emitting diodes\, soft ra
 diation detector\, hard radiation detectors\, etc. The 3D versions of thes
 e compounds adopt the three-dimensional ABX3 perovskite structure\, which 
 consists of a network of corner-sharing BX6 octahedra\, where the B atom i
 s a divalent metal cation (typically Ge2+\, Sn2+ or Pb2+) and X is a monov
 alent anion (typically Cl−\, Br−\, I−)\; the A cation is selected to
  balance the total charge and it can be a Cs+ or a small molecular species
 . Another class of materials gaining significance are the two-dimensional 
 (2D) perovskites -a blend of perovskites with layered crystal structure- (
 Ruddlesden-Popper type) offer a greater synthetic versatility and allow fo
 r 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 organic ca
 tions into the 2D framework and by controlling the slab thickness\, in con
 trast to the 3D analogues which have limited scope for structural engineer
 ing. We present the new homologous series\, (C(NH2)3)(CH3NH3)nPbnI3n+1 (n 
 = 1\, 2\, 3)\, of layered 2D perovskites which is different from Ruddlesde
 n-Popper type. These compounds adopt an unprecedented structure type which
  is stabilized by the alternating ordering of the guanidinium and methylam
 monium cations in the interlayer space (ACI). The these 2D perovskites com
 bine structural characteristics from both Dion-Jacobson (DJ) and Ruddlesde
 n-Popper (RP) structure archetypes. We also report the first examples of h
 ybrid DJ hybrid 2D lead iodide perovskites which consist of thick perovski
 te 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 deriving fr
 om a piperidinium (C5NH12) organic backbone. The new DJ perovskites are bu
 ilt from 3AMP (3AMP = 3-(aminomethyl)piperidinium) and 4AMP (4AMP =  4-(a
 minomethyl)piperidinium) spacers and methylammonium (MA) perovskitizers ca
 tions to form A’(MA)n-1PbnI3n+1 (A’ = 3AMP or 4AMP\, n = 1-4) homologo
 us series acting as spacers. Surprisingly\, a slight difference in the pos
 ition of the-CH2NH3+ group on the piperidine chair (3- and 4- position wit
 h respect to the piperidine nitrogen) exerts a strong influence on the cry
 stal structure\, which is reflected on the distortion of the inorganic lay
 ers. This difference has a major impact on the optical and electronic prop
 erties.
LOCATION:CE 1 4 https://plan.epfl.ch/?room==CE%201%204
STATUS:CONFIRMED
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