Nano- and single-crystals of lead halide perovskites: from bright light emission to hard radiation detection
Event details
| Date | 01.12.2016 |
| Hour | 16:30 › 17:30 |
| Speaker |
Prof. Dr. Maksym Kovalenko ETH Zurich Department of Chemistry and Applied Biosciences |
| Location | |
| Category | Conferences - Seminars |
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 edge 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. The photoluminescence of CsPbX3 NCs is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90% and radiative lifetimes in the range of 4-29 ns. Post-synthestic chemical transformations of colloidal NCs, such as ion-exchange reactions, provide an avenue to compositional fine tuning or to otherwise inaccessible materials and morphologies [2]. Identical synthesis methodology is perfectly suited also for hybrid perovskite nanocrystals of CH3NH3PbX3 [3] and CH(NH2)2PbX3 [4].
We also present low-threshold amplified spontaneous emission and lasing from CsPbX3 NCs [5]. We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440-700 nm) with low pump thresholds down to 5±1 µJ cm-2 and high values of modal net gain of at least 450±30 cm-1.
Here 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]. Such possibility arises from extremely high room-temperature mobility(µ)-lifetime(t) product of 1.8 × 10-2 cm2 V-1, low dark carrier density 109 - 1011 cm-3 and low density of charge traps (~1010 cm–3), and high absorptivity of hard radiation by lead and iodine atoms.
We also present low-threshold amplified spontaneous emission and lasing from CsPbX3 NCs [5]. We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440-700 nm) with low pump thresholds down to 5±1 µJ cm-2 and high values of modal net gain of at least 450±30 cm-1.
Here 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]. Such possibility arises from extremely high room-temperature mobility(µ)-lifetime(t) product of 1.8 × 10-2 cm2 V-1, low dark carrier density 109 - 1011 cm-3 and low density of charge traps (~1010 cm–3), and high absorptivity of hard radiation by lead and iodine atoms.
- L. Protesescu et al. Nano Letters 2015, 15, 3692–3696
- G. Nedelcu et al. Nano Letters 2015, 15, 5635–5640
- O. Vybornyi et al. Nanoscale 2016, 8, 6278-6283
- L. Protesescu et al. J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b08900
- S. Yakunin et al. Nature Communications 2015, 9, 8056.
- S. Yakunin et al. Nature Photonics 2016, 10, 585–589
Practical information
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Organizer
- Prof. Ulrich Lorenz
Contact
- Prof. Ulrich Lorenz