CdTe Quantum Dots/Layered Double Hydroxide Ultrathin Films with Multicolor Light Emission via Layer-by-Layer Assembly

Quantum dots (QDs) luminescent films have broad applications in optoelectronics, solid-state light-emitting diodes (LEDs), and optical devices. This work reports the fabrication of multicolor-light-emitting ultrathin films (UTFs) with 2D architecture based on CdTe QDs and MgAl layered double hydroxide (LDH) nanosheets via the layer-by-layer deposition technique. The hybrid UTFs possess periodic layered structure, which is verified by X-ray diffraction. Tunable light emission in the red-green region is obtained by changing the particle size of QDs (CdTe-535 QDs and CdTe-635 QDs with green and red emision respectively), assembly cycle number, and sequence. Moreover, energy transfer between CdTe-535 QDs and CdTe-635 QDs occurs based on the fluorescence resonance energy transfer (FRET), which greatly enhances the fluorescence efficiency of CdTe-635 QDs. In addition, a theoretical study based on the Forster theory and molecular dynamics (MD) simulations demonstrates that CdTe QDs/LDH UTFs exhibit superior capability of energy transfer owing to the ordered dispersion of QDs in the 2D LDH matrix, which agrees well with the experimental results. Therefore, this provides a facile approach for the design and fabrication of inorganic-inorganic luminescent UTFs with largely enhanced luminescence efficiency as well as stability, which can be potentially applied in multicolor optical and optoelectronic devices.