# Optical cooling of lead halide perovskite nanoparticles enhanced by Mie resonances

## TL;DR

This paper demonstrates a method to enhance nanoscale optical cooling in lead halide perovskite nanoparticles by engineering Mie resonances, achieving over 100 K temperature decrease under specific illumination conditions.

## Contribution

It introduces a novel approach to improve optical cooling efficiency in perovskite nanoparticles through Mie-resonance engineering at both absorption and emission wavelengths.

## Key findings

- Achieved over 100 K cooling in a perovskite nanoparticle under CW illumination.
- Optimized photoluminescence up-conversion via magnetic quadrupole and octopole resonances.
- Proposed simple fabrication method for nanocavity-based optical coolers.

## Abstract

Halide perovskites is a family of semiconductor materials demonstrating prospective properties for optical cooling owing to efficient luminescence at room temperature and strong electron-phonon interaction. On the other hand, perovskite based nanophotonic designs would allow for efficient optical cooling at nanoscale. Here we propose a novel strategy for enhancement of optical cooling at nanoscale based on optical resonances engineering in halide perovskite nanoparticles. Namely, photoluminescence up-conversion efficiency in a nanoparticle is optimized via excitation of Mie-resonances both at emission and absorption wavelengths. The optimized theoretically photo-induced temperature decrease is achieved for a hybrid halide perovskite (CH$_3$NH$_3$PbI$_3$) 530 nm nanoparticle on a glass substrate by more than 100 K under CW illumination at wavelength 980 nm and moderate intensities (7*10$^6$ W/cm2). The optimized regime originates from simultaneous excitation of magnetic quadrupole and magnetic octopole at pump and emission wavelengths, respectively. The combination of thermally sensitive photoluminescence signal and simplicity in fabrication of halide perovskite nanocavity will pave the way for implementation of nanoscale optical coolers for advanced applications.