Temperature-Dependent Electroabsorption and Electrophotoluminescence and Exciton Binding Energy in MAPbBr3 Perovskite Quantum Dots

Shailesh Rana, Kamlesh Awasthi, Sumit S. Bhosale, Wei-Guang Diau*, Nobuhiro Ohta

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Organic-inorganic lead halide perovskite nanocrystals have attracted much attention as promising materials for the development of solid-state light-emitting devices, but the existence of free or bound excitons or the formation of trap states remains under debate. We recorded the temperature-dependent electroabsorption (E-A) and electrophotoluminescence (E-PL) spectra, that is, electric-field-induced change in absorption and photoluminescence spectra, for methylammonium lead tribromide (MAPbBr3) colloidal perovskite nanocrystals, that is, quantum dots (QD), doped in a poly(methyl methacrylate) film in the temperature range of 40-290 K. Based on the results, the binding energy of the exciton (electron-hole pair) was estimated. The exciton binding energy of QD of MAPbBr3 estimated from the absorption and E-A spectra (∼17 meV) is nearly the same as that of a MAPbBr3 polycrystalline thin solid film, while the exciton binding energy estimated from the temperature-dependent PL spectra (∼70 meV) is much greater than that estimated from the absorption profile. The frequency dependence of the E-A intensity observed at 40 and 290 K for the modulated applied electric field indicates a slow ion migration in nanocrystals, which follows the modulation of the applied electric field at a frequency less than 500 Hz. The observed E-A spectra were analyzed with an integral method on assuming the Stark effect; the magnitudes of the changes in electric dipole moment and polarizability following photoexcitation were determined at each temperature from 40 to 290 K. E-PL spectra show that the PL of QD of MAPbBr3 is quenched on the application of an external electric field; the extent of quenching is much greater for trap emission than for exciton emission. Exciton-phonon scattering, which is responsible for the line broadening of the PL spectra, is also discussed based on the temperature-dependent PL spectra.

Original languageEnglish
Pages (from-to)19927-19937
Number of pages11
JournalJournal of Physical Chemistry C
Volume123
Issue number32
DOIs
StatePublished - 15 Aug 2019

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