Luminescent material - organic photoluminescence materials

A: what is the luminous light-emitting objects is a kind of absorption of energy, without hot stage, directly into the radiation characteristics of the phenomenon. 1, when a substance is motivated (rays, high-energy particles of an electric field, electron beam, etc.), the material will be excited, excited state of energy is released in the form of a light or heat. If this part of the energy is located in the visible, ultraviolet and near infrared electromagnetic radiation, this process is called luminescence process. 2, light is the material outside the thermal radiation in the form of light emit excess energy, the launch has certain duration. Which can realize the process of material called a luminescent material. 2: luminous type Luminescent material light way is varied, the main types are: photoluminescence, cathode ray emitting, electroluminescent, pyroelectric luminescence, interpretation of the glowing light, radiation light, etc. The photoluminescence and can be divided into organic, inorganic photoluminescence photoluminescence, etc. Three: organic photoluminescence 1, the luminescent principle of organic light-emitting materials is organic light-emitting molecule radiation produced by the return from excited state to ground state transition phenomenon. There are many ways to get organic molecular luminescence, photoluminescence electrons with the even most of organic matter, the ground state electron pairs of exists in each molecular orbital. According to Mr. Pollin Pauli exclusion principle, the same two electron spin on the tracks, by contrast, the total electron spin is zero, so the molecules in the electronic energy state of molecules called singlet (2 s + 1 = 0). When an electron absorbs the light energy in the molecules are stimulated, the often its spin, is excited singlet. If the excitation in the process of electronic spin flip, the excited triplet state. Triplet energy was lower than those of singlet. Often when organic molecules in light (photons) inspired by stimulated to inspire singlet (S), by vibration relaxation to the lowest level excitation singlet (S1), and finally by S1 return to ground state S0, fluorescence, or through a minimum excitation triplet (T1), (S1 - T1), and finally form the T1 - S0 electron transition, radiate phosphor at this time. 2, the classification of organic light-emitting materials organic light-emitting materials can be divided into: (1) the organic small molecules luminescent material; (2) organic polymer luminescent material; (3) the organic complexes luminescence materials. The luminescent material no matter on the luminescence mechanism, physical and chemical properties, or have their own characteristics in the application. There are many different kinds of organic small molecules luminescent material, they are with conjugated heterocyclic and various chromophores, structure is easy to adjust, with the introduction of olefinic bond, benzene and other unsaturated groups and all kinds of chromophores to change its conjugate length, so that the compound photoelectric properties change. Such as oxadiazoles and its derivatives, triazole and its derivatives, rhodamine and its derivatives, coumarin derivatives, 1, 8 - naphthalene imide derivatives, pyrazole Lin derivatives, three aniline derivatives, porphyrins, carbazole, pyrazine and thiazole derivatives,) derivatives, etc. They are widely used optics electronics, DNA diagnosis, photochemical sensors, dye, fluorescent brightening agent, fluorescent paint, laser dye [7], organic electroluminescent devices (ELD), etc. But small molecule luminescence materials in solid state under fluorescence quenching occurs easily, general device and easy to gather crystal made of doping method, device life down. So many researchers on the one hand, committed to the research of small molecules, on the other hand, looking for better performance of luminescent material, high polymer luminescent material was born.

Organic polymer optical material is usually divided into three categories: (1) the side chain type: small molecule luminescence group articulated on high molecular side chain, (2) the main chain of the conjugate type: all the molecules are a large conjugated polymer system, (3) the main chain of the conjugate type: luminescent centers on the main chain, but separated from each other between the luminescence center did not form a conjugated system. At present the research of polymer light-emitting materials mainly is conjugated polymers, such as polystyrene, poly (thiophene, fluorene, gathering three phenyl amines and their derivatives, etc. There are three phenyl amines, carbazole, polypyrrole, poly [8] porphyrins and their derivatives, copolymer, etc., the present study is more too. Can also introduce the light group introduced polymer end or among polymer chains, Kenneth p. Ghiggino etc. Introduce the fluorescent chromophore RAFT reagent, through the RAFT polymerization, connect the fluorescent chromophore in polymer. Can be seen from the above various kinds of light-emitting polymer, is most main chain conjugated polymer, main chain polymerization is easy to form bigger conjugate area, but its solubility, melting is lower, processing up more difficult; And introduce the light group introduced polymer end or among polymer chains, and only the end group, molecular weight will not very big, if the molecular weight is large, the shine group in the polymer content is low, weak fluorescence. The side chain of polymer luminescent material, is a powerful supplement to the main chain of conjugated polymers. 3, shining relation with structure of organic compounds can shine and light wavelength, luminous efficiency, mainly depends on its chemical structure. Fluorescence occurs when electrons with rigid plane and PI of molecular conjugate system. So luminous organisms often structure has the following characteristics: (1) with large PI bond structure. Conjugated system, the greater the delocalized electrons more easy to inspire, accordingly, fluorescence produced more easily. In general, the greater the aromatic system, the fluorescence peak is moving towards long wave, and fluorescence intensity tends to strengthen. For the same conjugate ring number of aromatic compounds, linear molecule fluorescence wavelength is longer than nonlinear molecule fluorescence wavelength. Anthracene, for example, the fluorescence emission of wave is taking longer than the Philippines. (2) the structure of rigid plane. A large number of studies have found that a relatively rigid plane of the structure of the compounds have good fluorescence properties, this is mainly caused by the vibration of dissipation within the result of the conversion rates. For example, azobenzene is a not fluoresce, organic matter and nitrogen fe molecules fluoresce, this is because the latter can be seen as azobenzene molecules are fixed by a carbon carbon double bond. The result of the similar example also many, can consider when designing functional molecules in molecular such bonds or space steric hindrance is introduced to reduce the vibration of the excited state energy dissipation, which is conducive to the generation of fluorescence. (3) more to the electronic group substituent. In general, the compound of conjugate system if you have strong electronic groups, such as: - NH2, - OH, - OR, etc., can strengthen the fluorescent compounds, to some extent because of phosphor containing such groups, the excited states often from hydroxy and amino outside the ring on the electronic excitation transfer to ring. Because of their electronic cloud is almost parallel to the track on the aromatic ring, in fact they Shared the conjugate electronic structure, and expanded its conjugated double bond system. So this kind of compounds absorb light and the wavelength of light emission than be substituted aromatic compounds long wavelength, the fluorescence efficiency increased. 4, the application of organic light-emitting materials (1) : photoresist photoresist is a key material in integrated circuit manufacturing process, its performance directly affects the circuit integration, also affect the microelectronics product strengths and weaknesses of the final performance. For a long time, due to factors such as technology and related support behind, microelectronics technology in China supporting dedicated photoresist critical infrastructure such as material has been hovering at a low level of research and production, including discrete device, liquid crystal display device and very large scale integrated circuit, microelectronics technology produce photoresist has been dependent on imports, directly affects the development of microelectronics technology in China. To change the unfavorable situation, formed in the aspects of intellectual property rights in our country, since the relevant ministries and commissions of the state "15" began to form a complete set of microelectronics technology such as photoresist with the material on the key development plan, and give a strong support. In May 2009, by Beijing progress microelectronic material co., LTD. Invest in the construction of our country's first hundred - ton high-grade photoresist line in shunyi district of Beijing built and put into production, it marked the beginning of our country have their own high-end photoresist products, microelectronics industry long-term dependence on imported photoresist situation will never be the end. (2) : lithium polymer batteries With the advent of the era of 3 g, will become the key factor restricting the development of mobile phone battery. If there is no big breakthrough on battery raw materials, liquid lithium ion battery capacity continue to ascend is very difficult; The capacity under the condition of existing critical state, safety factor will reduce. Based on the traditional liquid lithium ion battery development of polymer lithium battery (hereinafter referred to as lithium battery), just can make up for the traditional lithium-ion batteries in performance. Polymer lithium battery has a lighter, thinner, more capacity and characteristics of polymer lithium battery can be designed into any shape in principle, designed for mobile phones and other mobile devices provides a good condition. In addition, the adoption of gel polymer lithium battery electrolyte or solid substance, not leak, and thus reduce the pollution. Polymer lithium ion battery is composed of positive and negative electrodes, electrolyte and polymer diaphragm, among them, the diaphragm is lithium battery materials contains the highest technical barriers to a high value-added material, generally adopts the polypropylene (PP), polyethylene (PE) monolayer microporous membrane, and by the PP and PE composite multi-layer microporous membranes. With the development of lithium ion battery industry in our country, the original monopoly by foreign enterprises membrane technology has been mastered by domestic companies, currently, the main Chinese company can produce the diaphragm has shenzhen star source material technology co., LTD., foshan jinhui hi-tech photoelectric material co., LTD., etc. (3) : photoluminescence powder Photoluminescence powder is used for making ink, luminous paint, luminous plastic, light printing paste ideal material. Ink not only suitable for screen printing all kinds of luminous effect the patterns of the text, such as signs, toys, calligraphy and painting, glass painting, stickers, etc., but also because of its high transparency, good film-forming, thin coating, etc, can be in all kinds of embossing, the round (figure of Buddha, porcelain like, plaster model, the tang), polymer lighting and crafts such as painting, spray or screen printing, without affecting the original act the role of color or line under the premise of greatly improve its added value. Ink color: transparent, red, blue, green, yellow, etc. Photoluminescence materials application in safety is the most common. In terms of safety, photoluminescence materials can be used as a safe export indicator, evacuation marks, etc. When used as the marker, photoluminescence materials have to pass strict inspection, to ensure that they meet safety standards. Photoluminescence materials application in security and decorations or any other small items, luminescent material is asked to keep the brightest light and duration long lighting. 5, development trend of the development of organic light-emitting materials organic light-emitting materials is the key to break through the life limits. Although organic light emitting diode (OLED) materials development schedule looks good, recently the industry also revealed the efficiency and brightness gain breakthrough news continuously, however, in the field of the flexible lighting and display devices, there is still a main problem is in the air: life is too short of this kind of device. Director of market analysis firm IDTechEx Susann Reuter, points out that no matter how impressive the lighting display devices, or seems to be more elegant, consumers are not willing to buy products of life is too short. Lead to the problem of product life lies mainly in luminescent material itself, namely its sensitivity to moisture and oxygen. Reuter said that on the organic photovoltaics (organic photovoltaics, OPV) in terms of material too ─ ─ although compared with crystalline silicon, this new material has potential advantages of low cost processing method, but not even for some requirements for the application of long life, its life is still not long enough. Inorganic PV thin film materials, such as based on amorphous silicon, copper indium ingot selenium (CIGS) or cadmium telluride (CdTe) were less sensitive material, but also, when it comes to the product design of flexible or flexible, if asked about 20 years of product warranty, manufacturers often can't response. In OLED and OPV these two application cases, the glass can be present a better performance, because glass can provide good barrier property. But in a flexible, or based on polymer substrates such as applications, the situation was different. In such applications, the need for special coating and laminating technology to protect sensitive organic material. The industry has been on the field research and development, such as in the United States of California Vitex Systems, Reuter, points out that the company has developed a special stack with a combination of polymer with thin alumina layer of flexible substrates. For OLED and OPV, from industry evolution of basic research, is driving these new progress in the field of application. 6 and the future development direction of organic photoluminescence materials Research abroad on organic light-emitting materials is very extensive, from all performance parameters of the synthetic methods, materials, etc on the material of the luminous performance was a great deal of research, for some organic light-emitting materials has made a lot of production. More than the development of the domestic organic light-emitting materials in the laboratory stage, and the new species is less, the mass production reports is limited. And organic light-emitting materials as a kind of new functional materials, not only has important theoretical value, and it is a field full of broad prospects for development. The general research workers should intensify their efforts to research and promote organic light-emitting materials in the research, development and industrialization in our country, in order to meet the needs of post-pc era to the new material.