Emission color tuning of copolymers containing polyfluorene, benzothiadiazole, porphyrin derivatives

Copolymer containing benzothiadiazole (BT) and porphyrin (POR) derivatives as dopants (<0.3 mol%) was synthesized to polyfluorene (PF) backbone using Suzuki coupling reaction. The synthesized polymer was thermally stable and soluble in general organic solvents. UV–vis spectra of the polymer showed the similar behaviors in solution and on film. However, PL spectra was similar to PF in solution, but its peak increased around 520 and 612 nm as BT and POR, the dopants, went up in casting film. The more POR increased, the more effective Forster energy transfer was observed by POR than BT in PF. The device was made in ITO/PEDOT:PSS/polymer/BaF2/Ba/Al structure. For PFB02P05 polymer, the luminous efficiency was 0.66 cd/A, the power efficiency 0.29 lm/W and the maximum brightness 936 cd/m2. CIE coordinate (0.36, 0.34) was closer to pure white. For PFB15P20, the luminous efficiency was 1.40 cd/A, the power efficiency 0.32 lm/W, the maximum brightness 5997 cd/m2. PFB15P20 demonstrated the best performance as green emission.

Figure optionsDownload as PowerPoint slideHighlights
► We synthesized the porphyrin derivative as an red dopant.
► The synthesized PFBP polymer series showed good solubility and thermal stability.
► Charge balance was more effective in PFB15P20 compared other polymers.
► Polymers of PFB02P05 and PFB02P10 showed white color emission.