Control of Hot Carrier Relaxation in CsPbBr₃ Nanocrystals Using Damping Ligands

Abstract

In photon-conversion processes, rapid cooling of photo-induced hot carriers is a dominant energy loss channel. We herein report a 3-fold reduced hot carrier cooling rate in CsPbBr 3 nanocrystals capped with a cross-linked polysiloxane shell in comparison to single alkyl-chain oleylamine ligands. Relaxation of hot charge carriers depends on the carrier-phonon coupling (CPC) process as an important channel to dissipate energies in nanostructured perovskite materials. The CPC strengths in the two samples were measured through cryogenic photoluminescence spectroscopic measurements. The effect of organic ligands on the CPC in CsPbBr 3 nanocrystals is elucidated based on a damped oscillation model. This supplements the conventional polaronbased CPC model, by involving a damping effect on the CPC from the resistance of the ligands against nanocrystal lattice vibrations. The model also accounts for the observed linear temperature-dependence of the CPC strength. Our work enables predictions about the effect of the ligands on the performance of perovskite nanocrystals in future applications.

Improvement of Stability and Optoelectronic Properties of Blue-Emitting Perovskite Nanoplatelets by Microwave Treatment

“…The PB2 peak originates from the ground-state bleaching (GSB) because of the state filling of the carriers at the band edge. The PB1 peak originates from interstitial defects at high energy levels on the conduction band, and the PB3 peak originates from the bleaching signal at the energy level produced by the ion clusters after light irradiation. , Meanwhile, the MW-5s and the MW-5s-L samples only appear to have one negative PB peak at 456 nm. Therefore, the peak intensity of PB1 represents the number of interstitial defects (internal defects) in the as-grown sample.…”

Doping Colloidal Quantum Dot Materials and Devices for Photovoltaics

“…However, it is still a powerful tool to enhance the performance of perovskite CQD solar cells. Various two-step and one-step methods have been developed [17,[146][147][148][149][150]. Most of these works focused on surface passivation to enhance carrier transport and stability.…”

Slipping‐Free Halide Perovskite Supercrystals from Supramolecularly‐Assembled Nanocrystals

“…[ 1,2 ] PNCs are in the film or assembled state in various optical and photovoltaic devices. However, PNC assemblies show unusually long‐range carrier diffusion due to dielectric screening, [ 1d,3 ] exciton‐dressing, [ 4 ] excited state electron wavefunction overlapping, and the photon propagation effect (reabsorption). [ 1e,5 ] Furthermore, exciton splitting, hole trapping, and delayed non‐geminate recombination affect the electronic properties of these assemblies.…”