P band intermediate state (PBIS) tailors photoluminescence emission at confined nanoscale interface

Taiqun Yang,Bingqian Shan,Bo Peng,Peng Wu,Kun Zhang,Enhui Yuan,Fang Huang,Songqiu Yang

doi:10.1038/s42004-019-0233-1

Abstract

The availability of a range of excited states has endowed low dimensional quantum nanostructures with interesting luminescence properties. However, the origin of photoluminescence emission is still not fully understood, which has limited its practical application. Here we judiciously manipulate the delicate surface ligand interactions at the nanoscale interface of a single metal nanocluster, the superlattice, and mesoporous materials. The resulting interplay of various noncovalent interactions leads to a precise modulation of emission colors and quantum yield. A new p-band state, resulting from the strong overlapping of p orbitals of the heteroatoms (O, N, and S) bearing on the targeting ligands though space interactions, is identified as a dark state to activate the triplet state of the surface aggregated chromophores. The UV-Visible spectra calculated by time-dependent density functional theory (TD-DFT) are in quantitative agreement with the experimental adsorption spectra. The energy level of the p-band center is very sensitive to the local proximity ligand chromophores at heterogeneous interfaces.

Highlights

The availability of a range of excited states has endowed low dimensional quantum nanostructures with interesting luminescence properties
On the basis of the combined characterizations of the steady-state absorption, excitation, and time-resolved PL spectroscopy, we identify that the interfacial p-band intermediate state (PBIS) stems from the overlapping of p orbitals of the paired or more adjacent heteroatoms (O and S) bearing on the protected ligands on the metal core
The infrared adsorption spectrum (IR) and thermal gravimetric (TG) analyses showed strong evidences that the primitive GSH ligands could be completely replaced by 1dodecanethiol molecules (Supplementary Figs. 2 and 3), and the kinetics of the ligand exchange reaction followed a first-order reaction with a reaction rate constant of 5.78 min−1 in a mixture solution of ethanol and water (Supplementary Fig. 4)

Summary

Introduction

The availability of a range of excited states has endowed low dimensional quantum nanostructures with interesting luminescence properties. By manipulating the delicate surface ligand interactions on the individual metal nanocluster, the self-assembled metal NCs in superlattice, and the confined silica nanopores, we successfully achieve the precise control of emission colors and the systematic tuning of PL quantum yields and lifetimes. Our results isolate the role of the local patterning or spatial arrangement of surface ligands in the PL emissions of metal NCs. On the basis of the combined characterizations of the steady-state absorption, excitation, and time-resolved PL spectroscopy, we identify that the interfacial p-band intermediate state (PBIS) stems from the overlapping of p orbitals of the paired or more adjacent heteroatoms (O and S) bearing on the protected ligands on the metal core. Through-space conjugation within the ligand assembly domain provides effective emission luminogens This can be considered as a dark state to activate the triplet state of the surface aggregated chromophores by enhancing intersystem crossing

Methods

Results

Conclusion