Hybrid ZnO-Based Nanoconjugate for Efficient and Sustainable White Light Generation

Abstract

Developing new ways of generating white light is of paramount importance for the design of the next generation of smart, energy-efficient lighting sources. Here we report tunable white light emission of hybrid organic− inorganic nanostructures based on colloidal ZnO nanocrystals conjugated with organic fluorophores. These materials act as single nanophosphors owing to the distance-dependent energy transfer between the two components. The defect-based sizetunable ZnO nanocrystal blue-green emission coupled with complementary color emission from different fluorophores allows for the generation of white light with targeted chromaticity, color temperature, and color rendering index. We further show that silane layer-protected nanoconjugates result in increased stability of white light emission over a long period of time. The results of this work demonstrate an inexpensive, green, and sustainable approach to general solid-state lighting, without the use of rare earth or heavy metals. Colloidal form of the reported hybrid nanoconjugates allows for their further functionalization or incorporation into light-emitting devices. More broadly, size dependence of the electronic structure of native defects in transparent metal oxide nanocrystals and their electronic coupling with conjugated organic species could also represent a vehicle for introducing and manipulating new properties in these hybrid nanostructures.

Surface-specific visible light luminescence from composite metal oxide nanocrystals

“…The third class of system shown in Fig. 1 is polymerinorganic composites which are characterized by a chemically more complex and often scarcely characterized interface [5,[26][27][28][29]. These materials systems have a variety of advantages which start with the opportunity of self assembly and materials integration into hierarchically organized structures.…”

“…In particular, hybrid structures comprising biopolymers and functional inorganic phases can replace conventional materials in several high technology or bioapplications that are performed in the ambient or under biocompatible conditions. Many nanocomposites are composed of a luminescent organic dye that is attached to or incorporated in the inorganic nanoparticle [5,[26][27][28][29]. Chemical and thermal stability issues as well as materials deterioration via leaching of the luminescence component, however, are continued challenges in the development of this class of material.…”

Distance-Dependent Energy Transfer between Ga2O3 Nanocrystal Defect States and Conjugated Organic Fluorophores in Hybrid White-Light-Emitting Nanophosphors

“…The Fourier-transform infrared (FTIR) spectroscopic characterization of this type of nanoconjugates has suggested that binding of dye molecules to the surfaces of transparent metal oxide NCs is facilitated by the carboxyl groups. 30 While RhB can bind through the carboxyl group to NCs dispersed in hexane or toluene, any solvated molecules in such nonpolar solvents exist in the lactone form, which is distinctly nonemissive in orange-red and does not undergo resonance energy transfer due to the negligible intensity of the S 0 → S 1 absorption transition ( Figure S1b). Figure 1b shows an increase in the PL decay rate of Ga 2 O 3 NC trap emission as a result of binding of RhB, which is one of the common characteristics of FRET (see also Figure S2 in the Supporting Information).…”

“…We further suggested that rhodamine B (RhB) dye, as a model system, can bind to NC surfaces via the free carboxyl group, allowing for FRET mechanism. 30 In this paper, we quantitatively describe the FRET mechanism involving defect states in Ga 2 O 3 NCs as energy donors and organic fluorophores as energy acceptors to address the origin of white light generation and its control. On the basis of this analysis, we demonstrate the possibility to tune white light by controlling various synthetically accessible parameters, including NC size and surface coverage of dye molecules.…”

Lamellar Peptide–Cadmium‐Doped Zinc Oxide Nanohybrids That Emit White Light

“…Radovanovic et al. reported ZnO–ATTO fluorophore nanoconjugates for efficient and sustainable white‐light generation by controlling the Förster resonance energy transfer (FRET) process . Li et al.…”