Quasicubic model for metal halide perovskite nanocrystals

Abstract

We present an analysis of quantum confinement of carriers and excitons, and exciton fine structure, in metal halide perovskite (MHP) nanocrystals (NCs). Starting with coupled-band k ยท P theory, we derive a nonparabolic effective mass model for the exciton energies in MHP NCs valid for the full size range from the strong to the weak confinement limits. We illustrate the application of the model to CsPbBr3 NCs and compare the theory against published absorption data, finding excellent agreement. We then apply the theory of electron-hole exchange, including both short- and long-range exchange interactions, to develop a model for the exciton fine structure. We develop an analytical quasicubic model for the effect of tetragonal and orthorhombic lattice distortions on the exchange-related exciton fine structure in CsPbBr3, as well as some hybrid organic MHPs of recent interest, including formamidinium lead bromide (FAPbBr3) and methylammonium lead iodide (MAPbI3). Testing the predictions of the quasicubic model using hybrid density functional theory (DFT) calculations, we find qualitative agreement in tetragonal MHPs but significant disagreement in the orthorhombic modifications. Moreover, the quasicubic model fails to correctly describe the exciton oscillator strength and with it the long-range exchange corrections in these systems. Introducing the effect of NC shape anisotropy and possible Rashba terms into the model, we illustrate the calculation of the exciton fine structure in CsPbBr3 NCs based on the results of the DFT calculations and examine the effect of Rashba terms and shape anisotropy on the calculated fine structure.

Document Details

Document Type
Pub Defense Publication
Publication Date
Dec 17, 2019
Source ID
10.1063/1.5127528

Entities

People

  • Alexander Efros
  • John L. Lyons
  • Noam Bernstein
  • Peter C. Sercel

Organizations

  • California Institute of Technology
  • Office of Naval Research
  • United States Department of Energy
  • United States Naval Research Laboratory

Tags

Readers

  • Quantum Dot Semiconductor Device Photonics and Graphene Optoelectronic Materials and THz Physics.
  • Quantum spin resonance or Electron Paramagnetic Resonance spectroscopy.
  • Theoretical Analysis.

Technology Areas

  • Microelectronics
  • Quantum Computing