Study on Relationship between Electroluminescence Properties and Molecular Weight Distribution of Poly(9,9'-dioctylfluorene) Using Photoluminescence

Polyfluorenes (PFs) have attracted attention as conjugated polymer materials that can be promising as polymer-based emissive displays. PFs have a blue emission, a high photoluminescence (PL) quantum yield and thermal and chemical stabilities. The highly efficient blue emission from the PF structure is attractive for a display consisting of polymer light-emitting diodes (LEDs). We synthesized 10 kinds of poly(9,9'-dioctylfluorene) (PDOF) of different molecular weight distributions and studied their PL and electroluminescence properties. Moreover, we also studied their fluorescent lifetime. As a result, we found that optimum molecular weight of PF-based LEDs is about 105. From this result, it is thought that it is important to control the molecular weight of PDOF for PF-based LEDs.