Quantum defect-assisted multiphonon Raman scattering in metal halide perovskites

Area of Science:

• Materials Science
• Solid State Physics
• Quantum Optics

Background:

• Quantum defects significantly influence non-radiative recombination in metal halide perovskites.
• The Huang-Rhys factor quantifies charge carrier-optical phonon coupling, crucial for understanding recombination dynamics.
• Multiphonon processes are key to non-radiative recombination in perovskite photovoltaics.

Purpose of the Study:

• To theoretically investigate multiphonon Raman scattering mediated by defects in metal halide perovskites.
• To establish a method for evaluating the Huang-Rhys factor using Raman scattering.
• To explore combinational scattering modes and their role in charge-carrier lifetimes.

Main Methods:

• Theoretical modeling of multiphonon Raman scattering.
• Analysis of defect-mediated scattering involving longitudinal optical (LO) phonons.
• Consideration of deformation potential and Fröhlich interaction mechanisms.
• Investigation of combinational scattering between different mechanisms.

Main Results:

• Raman scattering exhibits multiple LO phonon overtones at regular intervals.
• The Huang-Rhys factor can be determined from the strongest overtone order.
• Combinational scattering modes between deformation potential and Fröhlich mechanisms were identified.
• Weak scattering intensities of combinational modes correlate with long non-radiative charge-carrier lifetimes.

Conclusions:

• Multiphonon Raman scattering provides a route to quantify charge carrier-phonon coupling via the Huang-Rhys factor in perovskites.
• The identified combinational scattering modes offer insights into the prolonged non-radiative charge-carrier lifetimes observed in these materials.
• This theoretical framework aids in understanding and potentially mitigating non-radiative recombination in perovskite-based devices.