title: Terahertz Conductivity within Colloidal CsPbBr3 Perovskite Nanocrystals: Remarkably High Carrier Mobilities and Large Diffusion Lengths.
abstract: Colloidal CsPbBr3 perovskite nanocrystals (NCs) have emerged as an excellent light emitting material in last one year. Using time domain and time-resolved THz spectroscopy and density functional theory based calculations, we establish 3-fold free carrier recombination mechanism, namely, nonradiative Auger, bimolecular electron-hole recombination, and inefficient trap-assisted recombination in 11 nm sized colloidal CsPbBr3 NCs. Our results confirm a negligible influence of surface defects in trapping charge carriers, which in turn results into desirable intrinsic transport properties, from the perspective of device applications, such as remarkably high carrier mobility (∼4500 cm(2) V(-1) s(-1)), large diffusion length (>9.2 μm), and high luminescence quantum yield (80%). Despite being solution processed and possessing a large surface to volume ratio, this combination of high carrier mobility and diffusion length, along with nearly ideal photoluminescence quantum yield, is unique compared to any other colloidal quantum dot system.
authors.affiliation: Department of Chemistry and ‡Department of Physics, Indian Institute of Science Education and Research (IISER) , Pune, India , 411008.
authors.forename: Gurivi Reddy
authors.initials: GR
authors.lastname: Yettapu
authors.affiliation: Department of Chemistry and ‡Department of Physics, Indian Institute of Science Education and Research (IISER) , Pune, India , 411008.
authors.forename: Debnath
authors.initials: D
authors.lastname: Talukdar
authors.affiliation: Department of Chemistry and ‡Department of Physics, Indian Institute of Science Education and Research (IISER) , Pune, India , 411008.
authors.forename: Sohini
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Department of Chemistry and ‡Department of Physics, Indian Institute of Science Education and Research (IISER) , Pune, India , 411008.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Swarnkar
authors.affiliation: Department of Chemistry and ‡Department of Physics, Indian Institute of Science Education and Research (IISER) , Pune, India , 411008.
authors.forename: Angshuman
authors.initials: A
authors.lastname: Nag
authors.affiliation: Department of Chemistry and ‡Department of Physics, Indian Institute of Science Education and Research (IISER) , Pune, India , 411008.
authors.forename: Prasenjit
authors.initials: P
authors.lastname: Ghosh
authors.affiliation: Department of Chemistry and ‡Department of Physics, Indian Institute of Science Education and Research (IISER) , Pune, India , 411008.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Mandal
keywords: CsPbBr3 perovskite nanocrystals; carrier mobility; density functional theory; phonon; quantum dots; time-resolved THz; ultrafast carrier dynamics