Synthesis and Electro-Optical Properties of Fluorene Based Light Emitting Materials
|關鍵字:||芴;有機發光二極體;聚芴;fluorene;organic light emitting diode;polyfluorene|
|摘要:||本研究主要目的在於合成以fluorene為基礎的發光材料及其在光電上的應用。本研究所合成的發光材料共分高分子P1∼P3及小分子O1，這P1~P3皆以Suzuki coupling方式聚合，在熱性質表現方面以P3最佳，其Td超過450℃且Tg達185℃，隨著溶劑極性的變化這四個材料的PL也隨之改變，P1、P2及O1因主鏈上極性雜原子與較高極性的溶劑之dipole-dipole interaction的影響，故其PL在THF溶液中會較在Toluene溶液中紅位移，而P3因主鏈皆為碳原子所組成，故dipole-dipole interaction較不明顯而是以與含芳香環溶劑間的π- stacking interaction為主要作用力，所以PL表現與其他三個材料相反，一般而言，薄膜的PL會較溶液紅位移，但O1在THF溶液中的PL卻明顯較薄膜紅位移。
P1與O1因共軛長度相同故其能隙相同，但其HOMO位置卻明顯不一樣，P1的HOMO為 –5.35 eV，O1的HOMO為 -4.91 eV，P1與P2在主鏈上分別導入氮原子及硫原子，這使得這兩個材料的光色、元件效率有著明顯不同，P1的EL因堆疊作用造成在650nm ∼700nm間有一波峰出現造成光顏色的改變，此一現像可藉由與PVK摻混而獲得改善，而P3為一藍綠光材料，其發光效率可藉由tbftb的加入而提升。|
The goal of this research is to study the synthesis and the application of the light emitting materials based on fluorene. The light emitting materials of this research are divided into two components. The one is polymer P1 ~ P3, another is small molecular O1. Polymers P1 ~ P3 are polymerization by Suzuki coupling. On the thermal properties, P3 is the best because it’s Td is over 450 ℃ and Tg is as high as 185 ℃. PL of theses materials will change as the polarity of the solvent. PL of theses materials except P3 in THF solution is more red-shift than in toluene solution because dipole-dipole interaction is the dominated force between heteroatoms on the main chain and more polar solution. The main chain of P3 consists of carbon atom. Dipole-dipole interaction become minor force. The π- stacking interaction between P3 and aromatic solvent is dorminated force. Thus, PL of P3 in toluene solution is more red-shift than in THF solution. In general, PL of the state of the film is red-shift than PL of the state of the solution, but O1 is red-shift in THF solution than in the state of the film. Because the conjugated length of P1 is the same as O1, their energy gap are equal.But their HOMO level are not the same. The HOMO level of P1 is – 5.35 eV. The HOMO level of O1 is – 4.91 eV. The nitrogen atom and the sulfur atom on the main chian of P1 and P2 resulted in the different color of light and performance of their devices. Because of aggregation EL of P1 had the appearance of a peak during 650 nm ~ 700 nm. The phenomenon can be improved by P1 blending with PVK. P3 is the materials that can produce blue-green light. It’s efficiency can be promoted by adding tbftb into P3.