OLED is an injection type light-emitting device, and its basic configuration is a sandwich structure formed by sandwiching an organic thin film layer between two electrodes. In order to meet the requirements of material properties and device performance, the structure of OLED has developed from the original single-layer structure to the current multi-layer device. The optimization of the structure plays a very important role in improving the luminous efficiency and performance stability of the device. Transport layers, electron transport layers, and light-emitting layers are functional layers necessary to achieve efficient light emission in multilayer device structures. OLED synthetic reagents are mainly organic small molecule synthetic reagents and organic polymer synthetic reagents for synthesizing functional layers.
Organic small-molecule materials are easy to synthesize and purify, and a large number of organic small-molecule synthetic reagents have been applied to vapor deposition devices. Generally, the solubility of organic small molecule synthetic reagents is improved by substituents, and the solid-state crystallization is suppressed by designing the three-dimensional structure of the molecules. Scholars reported a series of red light small molecule synthetic reagents, each of which used 4,7-bis(thiophen-2-yl)benzo[C][1,2,5 ]Thiadiazole as the core, monofluorene or difluorene to modify the end group, and through the alkyl chain of fluorene to increase the solubility of the material, and finally capped with trimethylsilyl, triphenylamine or benzofuran. The synthesis steps of such fluorescent materials are conventional and simple, and the properties of the synthesized materials are also very good.
Organic polymer synthetic reagents usually have a quasi-one-dimensional conjugated structure, and properties such as emission wavelength and solubility largely depend on the nature and regularity of their side chains. Among them, fluorene derivatives have wide band gaps, strong fluorescence quantum efficiency and spectral stability, and are the most commonly used blue light conjugated polymerization units. Polyfluorene p-type materials are dominated by hole transport, and the electron and hole transport are unbalanced. Usually, side chain or end group modification is required to improve, such as the introduction of electron transport groups, end capping to block hole transport, etc. Scholars reported a polymer, PFSO10TA, which was synthesized by synthesizing S,S-dioxy-dibenzothiophene (SO) on the main chain of polyfluorene and capping it with triphenylamine (TA) at the same time. In order to inhibit the intramolecular charge transfer and enhance the luminous efficiency.