Au Exchange or Au Deposition: Dual Reaction Pathways in Au–CsPbBr₃ Heterostructure Nanoparticles

Abstract

We have designed a facile synthetic strategy for the selective deposition of Au metal on all-inorganic CsPbBr perovskite nanocrystals that includes the addition of PbBr salt along with AuBr salt. PbBr is necessary because the addition of Au to solutions of CsPbBr nanocrystals otherwise results in the exchange of Au ions from solution with Pb cations within the nanocrystal lattice to produce CsAuAuBr nanocrystals with a tetragonal crystal structure and a band gap of about 1.6 eV, in addition to Au metal deposition. Including excess Pb ions in solution prevents the exchange reaction. Au metal deposits on the surface of the nanocrystals to produce the Au-CsPbBr heterostructure nanoparticles with an Au particle diameter determined by the Au ion concentration. Fluorescence quenching caused by Au deposition monotonically increases with deposition size, but the fluorescence quantum yield (QY) is significantly greater than if any cation exchange has occurred. An optimized synthesis can produce Au-CsPbBr nanoparticles with 70% QY and no evidence of cation exchange.

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr3 anti-Stokes photoluminescence

“…In comparison with the control, the uniform Au nanoparticle coverage sample emits an additional 10.1 meV of thermal energy per up-converted photon. It is known that coupling fluorescent semiconductors to a metal decreases their fluorescent lifetime [20], and this has been additionally demonstrated for CsPbBr 3 with Au nanoparticles deposited on the perovskite surface [21]. One explanation of the blue-shift reported here may be that the reduction in the fluorescence lifetime prevents the energy transfer between particles that would result in red-shifted emission.…”

Efficient plasmon-hot electron conversion in Ag–CsPbBr3 hybrid nanocrystals

“…Time-resolved PL spectra are recorded to check the effect of SPR on the interband recombination dynamics. In principle, multiple factors may contribute to PL dynamics including the emission enhancement caused by passivation of surface traps and the fluorescence quenching of the semiconductor by the metal, which is also dependent on the size of metallic nanoparticles 45 . In this study, time-resolved PL spectra in Ag–CsPbBr 3 hybrid NCs with Ag nanoparticles of ~5.5 nm and neat CsPbBr 3 NCs are nearly the same at the late stage (Fig.…”

Plasmonic CsPbBr3–Au nanocomposite for excitation wavelength dependent photocatalytic CO2 reduction

“…TiO 2 , ZnO) with visible light responsivity [18][19][20] . Very recently, CsPbBr 3 -Au nanocomposite has been successfully fabricated via in-situ reducing AuCl 3 with the surface bound oleylamine ligand [20][21][22][23] . However, the size of the resultant Au NP is too small to produce LSPR effect [21] .…”