A series of fluorene derivatives containing nonsymmetric and bulky aromatic groups at C-9 position were synthesized and used for the preparation of blue- light-emitting copolyfluorenes (P1-P4) by the Suzuki coupling polycondensation. The copolymers were characterized by molecular weight determination, elemental analysis, differential scanning calorimeter, thermogravimetric analysis, absorption and emission spectroscopy, cyclic voltammetry, and differential pulse voltammetry. Their decomposition temperatures and glass transition temperatures are 423-441 ̈C and >120 ̈C, respectively. In film state, the copolyfluorenes exhibit blue photolumines- cence at 425-450 nm, which remains almost unchanged after annealing at 200 ̈Cin air for 60 min. Polymer light-emitting diodes [ITO/PEDOT:PSS/P1-P4/Ca(50 nm)/ Al(100 nm)] show stable blue-light emission under device operation with the CIE coordinates being between (0.16, 0.07) and (0.17, 0.09). The light-emitting diodes devices from P1 and P3 containing electron-deficient oxadiazole units display enhanced performance, with the maximum brightness and maximum current efficiency being (4510 cd/m2 and 2.40 cd/A) and (2930 cd/m2, 1.19 cd/A), respectively.
|Number of pages||14|
|Journal||Journal of Polymer Science, Part A: Polymer Chemistry|
|Publication status||Published - 2009 Jun 1|
All Science Journal Classification (ASJC) codes
- Polymers and Plastics
- Organic Chemistry
- Materials Chemistry