Preparation Of Quantum-Dot Luminescent Thin Films And Their Construction Of White-Light Devices

Based on the superior optical properties of quantum dots(QDs), in this paper, hydrophobic QDs were modified with monooctyl maleate to obtain water soluble QDs, and then the polymer/QDs and QDs/QDs luminescent films were fabricated through Layer-by-layer electrostatic assembly technology. The fluorescence properties of thin films were simply investigated and then the luminescent films were preliminarily applied to build white light device. Flexible luminescent materials, with the advantages of foldability and crack resistance, have been widely used in collapsible optoelectronic devices. QDs as the luminescent centers were embedded into the inorganic matrix by spray drying technology to obtain the QDs phosphor. The mixture of red QDs phosphor and polymer were cured to get flexible luminescent films, which can be used in combination with the commercial white LED to improve the quality of white light.The main work of this paper includes:(1)Layer-by-Layer assembly of stable aqueous quantum dots for luminescent films. This work reports the fabrication of a luminescent planar plate based on stable aqueous quantum dots(QDs) and poly(diallyldimethylammonium chloride)(PDDA) via a layer-by-layer(LBL) assembly technique. Preparation of aqueous QDs with facile monoalkyl maleate amphiphilic surfactants as the coating agent is conducted by a robust and efficient phase-transfer method. The as-prepared aqueous QDs exhibit bright emission, and their surface has very large negative zeta potential values, which are useful for electrostatic LBL assembly. Red, green, and blue luminescent planar plates are successfully fabricated via LBL assembly of the monocolor QDs, respectively. Through accurately adjusting the relative proportion of each monocolor luminescent component, we obtain an inspiring luminescent planar plate, which emits bright white light with a color coordinate of(0.3509, 0.3483), a correlated color temperature(CCT) of 4766 K, and a high color rendering index(CRI, Ra) of 89.5 under the irradiation of UV light. In order to simplify the process and reduce the influence of the polymer for the luminescent film, two kinds of QDs with opposite charge were assembled to obtain QDs/QDs luminescent film. Mono-color or multi-color even white color luminescent films can be obtained through assembling of the same color or different color of QDs. Therefore, this paper reports a facile process for the design and preparation of luminescent planar plates, which have potential applications in display and solid-state lighting devices.(2)High quality red-emitting phosphors with quantum dots serving as luminescent centers for solid-state lighting. herein we proposed a new concept of quantum dot phosphors(QD-phosphors). A series of phosphors based on colloidal quantum dots(QDs) embedded into inorganic salts or oxide via spray-drying technology are reported. QDs as the luminescent centers were uniformly dispersed in the nearly micrometer-sized inorganic matrix. Such QD-phosphors preserve the superior optical properties of incorporated QDs, such as tunable and pure colors, bright emission and broadband absorption. Furthermore, the red QD-phosphors are integrated with polydimethylsiloxane(PDMS) to obtain the flexible composite films with certain scattering ability, which are combined with the commercialized white light-emitting diode(WLED) to achieve a significantly improved color rendering index(CRI) of > 90, the correlated color temperature(CCT) of < 6000 K and a more close to the standard coordinates of white light(0.333, 0.333).