In most perovskite nanocrystal (PeNC)-based optoelectronic and photonic applications, surface ligands inevitably lead to a donor–bridge–acceptor charge transfer configuration. In this article, we demonstrate successful modulation of electron transfer (ET) rates from all-inorganic CsPbBr3 PeNCs to mesoporous titanium dioxide films, by using different surface ligands including single alkyl chain oleic acid and oleylamine, cross-linked insulating (3-aminopropyl)triethoxysilane and aromatic naphthoic acid molecules as the ligand-bridge. We systematically investigated the ET process through time-resolved photoluminescence spectroscopy. Calculations verified the ligand-bridge barrier effect of the three species upon the ET process. Transient absorption measurements excluded carrier-delocalization effect of the naphthoic acid ligands and confirmed the bridge-barrier effect. Our work provides a perspective for composable and appropriate ligands design for diverse practical purposes.

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 CsPbBr3 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 CsPbBr3 nanocrystals is elucidated based on a damped oscillation model. This supplements the conventional polaron‐based 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.

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.

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