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SUMMARY:Nano- and single-crystals of lead halide perovskites: from bright 
 light emission to hard radiation detection
DTSTART:20161201T163000
DTEND:20161201T173000
DTSTAMP:20260916T050604Z
UID:6b0cb81db98cc045943fa61e1d265dba2d2eff864e72fe7ac69002b2
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dr. Maksym Kovalenko\nETH Zurich\nDepartment of Chemistr
 y and Applied Biosciences\n Chemically synthesized inorganic nanocrystals
  (NCs) are considered to be promising building blocks for a broad spectrum
  of applications including electronic\, thermoelectric\, and photovoltaic 
 devices. We have synthesized monodisperse colloidal nanocubes (4-15 nm ed
 ge lengths) of fully inorganic cesium lead halide perovskites (CsPbX3\, X=
 Cl\, Br\, and I or mixed halide systems Cl/Br and Br/I) using inexpensive 
 commercial precursors [1]. Their bandgap energies and emission spectra are
  readily tunable over the entire visible spectral region of 410-700 nm. T
 he photoluminescence of CsPbX3 NCs is characterized by narrow emission lin
 e-widths of 12-42 nm\, wide color gamut covering up to 140% of the NTSC c
 olor standard\, high quantum yields of up to 90% and radiative lifetimes i
 n the range of 4-29 ns. Post-synthestic chemical transformations of collo
 idal NCs\, such as ion-exchange reactions\, provide an avenue to compositi
 onal fine tuning or to otherwise inaccessible materials and morphologies [
 2]. Identical synthesis methodology is perfectly suited also for hybrid pe
 rovskite nanocrystals of CH3NH3PbX3 [3] and CH(NH2)2PbX3 [4].\n \nWe also
  present low-threshold amplified spontaneous emission and lasing from CsPb
 X3 NCs [5]. We find that room-temperature optical amplification can be obt
 ained in the entire visible spectral range (440-700 nm) with low pump thr
 esholds down to 5±1 µJ cm-2 and high values of modal net gain of at leas
 t 450±30 cm-1.\n \nHere we also demonstrate that 0.5-1 centimeter large
 \, solution-grown single crystals of APbI3  (where A is methylammonium  
 or  formamidinium mixed with Cs+) can serve as inexpensive\, operating at
  ambient temperatures solid-state gamma detectors (e.g. for direct sensing
  of photons with energies as high as mega-electron-volts\, MeV) [6].  Suc
 h possibility arises from extremely high room-temperature mobility(µ)-lif
 etime(t) product of 1.8 × 10-2 cm2 V-1\, low dark carrier density 109 - 1
 011 cm-3 and low density of charge traps (~1010 cm–3)\, and high absorpt
 ivity of hard radiation by lead and iodine atoms. \n \n\n	L. Protesescu 
 et al. Nano Letters 2015\, 15\, 3692–3696\n	G. Nedelcu et al. Nano Lette
 rs 2015\, 15\, 5635–5640\n	O. Vybornyi et al. Nanoscale 2016\, 8\, 6278-
 6283\n	L. Protesescu et al. J. Am. Chem. Soc. 2016\, DOI: 10.1021/jacs.6b0
 8900\n	S. Yakunin et al. Nature Communications 2015\, 9\, 8056.\n	S. Yakun
 in et al. Nature Photonics 2016\, 10\, 585–589\n\n \n 
LOCATION:CH G1 495 https://plan.epfl.ch/?room==CH%20G1%20495
STATUS:CONFIRMED
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