Polymides (PIs) have been studied as high-performance materials due to their outstanding thermal stability, oxidative stress, chemical resistance, and excellent mechanical and electrical properties. They have been widely used in the field of gas separation, microelectronics, space devices, integrated electronic circuits, passivation coatings, substrate components, adhesives, composites and so on [1-2].
Composite materials studies have attracted increasing attention in the development of new functional materials for potential application fields which involve energy storage systems as super capacitors, sensing, catalysis, and drug delivery[3–6] for that, composites with nanostructured materials provide interactions between the different components, resulting in a material with combined properties which overcomes the disadvantages of the individual materials[7,8] .Nowadays, combination between an organic, namely polymers, with an inorganic component, that is, metal nanoparticles or metal oxides, has offered novel nanocomposites with interesting properties in which a synergistic effect between the organic-inorganic components offer outstanding properties and performance Examples of these evidences have been observed in composite materials based on CdS, MnO2, SnO2, and IrO2 with polymers, demonstrating remarkable performance in super capacitor applications, high sensitivity as gas-sensor, bioactive phases, and catalysis[9–11] .
Polyimide films showed significantly enhanced fluorescence emissions within the visible region owing to the suppression of the charge transition interactions through the introduction of alicyclic diamines. However, these fluorescent Polyimides exhibit relatively small Stokes shifts, namely, an energy gap between the excitation (absorption) and emission wavelengths; consequently, a notable enhancement of the Stokes shifts is needed for photo luminescent polymers applied to solar-spectrum converters. We also reported that Polyimide films containing −OH exhibit a large Stokes-shifted fluorescence originating from the excited state through an intramolecular proton transfer [13-15].
Room-temperature phosphorescence in organic molecules has recently attracted significant attention owing to the resulting extremely large Stokes shifts and ultra-long luminescence lifetime [16,17]. Frequently, phosphorescence doesn't happen often at room temperature in air because it is easily deactivated by local molecular motion and energy transfer to oxygen during the ultra-long lifetime of the excited triplet state. There are two major strategies used to obtain room-temperature phosphorescence materials. One is to enhance the intersystem crossing efficiency by introducing heavy atoms such as metallic atoms and/or phenyl−carbonyl groups into the molecular structure. Such heavy atoms effectively enhance the intersystem crossing because of their large spin−orbit coupling, which is termed the “heavy-atom effect “. Meanwhile, the incorporation of carbonyl groups facilitates intersystem crossing through the transitions allowed from 1 (n → π*) to 3 (π → π*) . Another way is to reduce non-radioactive processes in an excited state by suppressing the local molecular motion, either by cooling to extremely low temperatures or by applying high pressure. For this reason, most room-temperature phosphorescence materials have been studied under cryogenic conditions below the temperature of liquid nitrogen in transparent rigid matrices such as crystalline compounds or in host−guest systems [20,21]. However, such systems are impractical for use in solar-spectrum converters.
Recently the field of flexible displays has seen a great development due to their applications in wearable devices, smartphones and other emerging displays. To obtain adequate efficiencies, however, it is necessary to know in depth the technical characteristics of these devices. That is the reason why this field is attracting the attention of many researchers whose aim is to develop new lines of basic research in order to solve the problems facing this industry. Interest in polymeric light-emitting materials is growing in this most crucial field due to their flexible nature and facile film formation by spin coating  or inkjet printing . Conjugated polymers, such as poly(thiophene)  and polyfluorene  have become important light-emitting materials in large-area display devices, typically known as Polymer Light Emitting Diodes (PLEDs), BY showing great potential in advanced flexible displays.
CdS is a typical II-VI semiconductor compound with two crystal forms: a wurtzite type as a hexagonal phase and a sphalerite type as a cubic phase. It has a direct band gap of 2.42 eV, good response to visible light, and good optical, photo physical and photochemical properties. Therefore, cadmium sulfide semiconductors can be considered promising materials in the fields of nonlinear optics and solar energy conversion, as photo catalysis, solar cells, etc. [26-30].
Fluorescent carbon quantum dots (CDs) are a new class of functional carbon nanomaterials and attracted great interest because of their versatile applications in optoelectronics, biomedical applications and chemical biosensors [31-33]. All Nano-sized fluorescent carbon materials with one dimension less than 10 nm can be classified as CDs, and these can be obtained from various carbon materials such as fullerenes, carbon nanotubes and graphene [34-36]. Conventional semiconductor quantum dots and organic dyes have the disadvantages of cumbersome preparation methods, high cost, toxicity and easy photo bleaching. Compared to them, CDs have high fluorescence efficiency, good water solubility, easy synthesis, low toxicity and, furthermore, good biocompatibility, high stability, surface modification capability and other advantages. They have a wide application value in many fields such as biology, chemistry and medicine [37-41]. Therefore, CDs have received more and more attention by the applied research at home and abroad so that various types of carbon quantum dots with excellent performance were developed: they are expected to become substitutes for traditional semiconductor quantum dots and organic dyes in the future.
Mesoporous silica material makes use of organic molecules (surfactants or amphiphilic block polymers) as a template: after the template is removed by calcinations or solvent extraction, the interface reacts with the inorganic silicon source to form a regular order system. The SiO2 is assembled to form a porous nanostructure composite material retaining the inorganic skeleton of SiO2. Due to its large specific surface area, high porosity, adjustable pore size, low material density, strong adsorption and assemblability, it shows broad application forecasts in the fields of catalytic carriers, gas adsorption and separation, drug delivery and chemical sensors .
It can be successfully developed thermally stable and highly transparent Room-temperature phosphorescence PIs with controlled optical properties, such as tunable luminescent colors, using a copolymerization technique. Such CoPIs are promising for light-emitting materials applicable to color tunable solid-state emitters, ratio metric oxygen sensors, and solar-spectrum converters  and also we have successfully fabricate highly thermally conductive and electrically insulating PI composite films filled with Graphene Oxide in three steps: in situ polymerization, self-assembly, and subsequent casting and thermal treatment .
A very interesting prospect could be to study a possible replacement material for SiO2 that has better characteristics in terms of cost, manageability and eco-compatibility: diatomite seems to have these features. Diatomite is a material formed by the deposition of the remains skeletons of single-cell aquatic plants, the diatoms. Diatomite is a non-metallic mineral whose main chemical composition is amorphous silica, accompanied by a small amount of clay impurities such as Montmorillonite and Kaolinite, and organic matter. In Diatomite different shapes of algae can be seen under the microscope; each alga varies in size from a few microns to several tens of microns, and they show many Nano-scale pores on their surface. Due to its porous structure, low density, large specific surface area, stable physic-chemical properties, strong adsorption performance, acid resistance, non-toxicity and odorless properties, diatomite has long been used as filters aid, thermal insulation material, anti-adhesive agent, desiccants. Furthermore, its abundance in mineral resources, wide source and low price make the China's diatomite a material widely used in various fields as carrier and functional filler.
Due to these excellent properties, mesoporous silica and diatomite have become ideal carriers for various nanoparticles. The combination of cadmium sulfide and silica matters not only has the advantages of low water absorption, low thermal expansion coefficient and high temperature resistance, but also has excellent fluorescent properties and enhances the performance of the composite film.
Therefore, in this research, mesoporous silica and diatomite are used as carriers to combine cadmium sulfide and carbon quantum dots on the surface, that are combined with polyimide, in a blending manner, to prepare a composite film with fluorescent properties. A characterization of different properties of the film is then carried out to evaluate possible application perspectives