Synthesis And Luminescent Properties Of Organic Small Molecule Based On Electron Donor-Acceptor Structure And Its Copolymer

Organic electroluminescent (EL) materials play the core role in OLED. To gain a high quality organic light emitting diode (OLED), it is very essential to choose a property EL material. In terms of full-color display, compared with the blue-emitting and green-emitting materials, the red-emitting material still remains a challenge due to concentration quenching efficiency result from its shorter molecular distances in thin solid film. Generally, the red-emitting materials can only be used as the dopped material. So it is difficult to control and repeated effectively for fabricating OLED devices. The above urgency promoted us to search for better and new red-light emitting materials with the proper energy gap and high solid-state photoluminescence (PL) quantum yield. Polymer light emitting devices have a promising application prospect on white light illuminated. A single-chain white polymer light emitting device applied in white light illuminated can give top priority to its simple polymer material processing technology and the potential advantaged of competitive price. However, there are few kinds of single white polymer materials and the principal problems of which are color quality and luminous efficiency. So it had been a problem of desiderate to solve that synthesizing single white polymer materials with better luminescent properties.Suzuki coupling reaction was employed to synthesis a new type of bipolar small molecular host red-light emitting material with the linear D-A structure-2,7-di (2-thienyl) fluoren-9-one (DTFO) whose electrical property was simulated. Its chemical structure, physical property, thermal stability and the film formability were studied in detail. Results show that DTFO exists as the nearly flat, linear and alternating conjugate structure with dual fluorescent phenomenon in a dilute solution. Meanwhile, as the DTFO concentration increases, aggregation-induced emission phenomenon appeared. In addition, DTFO in solid state possesses excellent thermal stability and film formability, which glass transition temperature reach to 145℃. CIE coordinate of (0.66,0.34) with performance (λmax=614nm,φf=68%) was obtained in solid state.Three different kinds of newly typed polymer material were synthesized by using polyfluorene and DTFO possessing the balanced carrier transporting as blue-light and red-light units, respectively. The white-light emission was achieved by modulating the ratio of light units.The molecular structure, molecular weight, distribution of molecular weight, thermal stability, photophysical and electroluminescence properties of polymer were investigated. Results show that the three polymers with different ratio all had the molecule weight larger than 10000 with narrow distribution. The polymers in this paper showed good thermal stability. When the polymer which the ratio is 1000/1 was used as the light emitting layer material, white-light emission can be attained with the CIE coordinate of (0.33,0.34) under 14.2V driven voltage.