All-quantum-dot emission tuning and multicolored optical films using layer-by-layer assembly method

In this report, all-quantum-dot multilayer photoluminescent films (PLFs) based on two types of modified quantum dots (MA-C8-QDs and PEI-QDs) were fabricated through the layer-by-layer (LBL) self-assembly method, providing a new kind of luminescent material with emission color covering blue to red spectral region. Aqueous QDs with high stability and photoluminescence properties were obtained by an efficient phase transfer, followed by fabrication of (PEI-QDs/MA-C8-QDs)n PLFs with alternate adsorbing the layer of the MA-C8-QDs endowed with negative (COO−) charges and PEI-QDs endowed with positive (NH3+) charges using electrostatic interactions between each layer. The resulting single color films preserved good color purity and strong luminescence of original QDs, PL intensities increased linearly with the number of bilayers n, which indicated that growth of the film is regular and uniform. In addition, the uniform and smooth PLFs as prepared have high visible light transmittance. Furthermore, by emission tuning, multicolor and white light-emitting PLFs with the color coordinates at (0.3292, 0.3418) have been easily obtained by assembly of two types of modified red, green, blue QDs. Therefore, these PLFs (especially white-light PLFs) show promise for the development of novel multiplexed biological sensors, full-color displays, intelligent response, photonic, and optoelectronic devices.