Easy synthesis of silver nanoparticles-orange emissive carbon dots hybrids exhibiting enhanced fluorescence for white light emitting diodes

Ag nanoparticles (NPs) show a excellent surface plasmon resonance (SPR), which is expected to enable fluorescence enhancement. In this study, a facile approach is proposed for fabrication of Ag NPs/long-wavelength carbon dots (Ag-LCDs) hybrids, wherein Ag NPs work as a fluorescent reinforcer to enhance photoluminescence (PL) intensity of LCDs. The largest enhancement was acquired through adjusting the volume ration between Ag NPs and LCDs. In this process, PL decay is considered as an important and simple characterization to speculate the metal enhanced fluorescence (MEF) mechanism. On the basis of result of small reduction in lifetime, we proposed that the mechanism may be predominantly derived from the localized effectric field effect and partly from the intrinsic radiative decay rate. Moreover, spin-coating technology was utilized to produce LCDs and Ag-LCDs hybrids films. Then, white light-emitting diodes (white LEDs) were constructed by these films with controllable thicknesses and GaN chips. The constructed white LED presented excellent optical performances with an optimal color coordinates (CIE) of (0.33, 0.35), a color rendering index (CRI) of 74.6, a correlated color temperature (CCT) of 5435 K. Notably, the existence of Ag NPs enable these LCDs to improve the luminous efficacy (LE) from 32.63 lm W−1 to 41.26 lm W−1. Such superior optical merits enable them the promising potentials for application in optical devices.