Optical properties of oligo(9,9-diarylfluorene) derivatives in thin films and their application for organic light-emitting field-effect transistors

We Demonstrated That Oligo(9,9-diarylfluorene) Derivatives Have High Potential for Optoelectron. Applic. Such as Organ. Lasers and Light-emitting Organ. Fld.-effect Transistors (LE-OFETs). the Oligo(9,9-diarylfluorene) Derivatives Have High Photoluminescence Quant. Efficiencies up to Φ _PL ≈ 70-75% and very low amplified spontaneous emission thresholds (E_th) down to 0.5 μJ/cm² in their vacuum-deposited neat films. In particular, the trimer derivatives (B3 and T3) show higher Φ_PL and lower E_th than those of the dimers (B2 and T2). Efficient deep-blue LE-OFETs with the electroluminescence (EL) peaking at λ_peak - 429 nm were demonstrated using the ter(9,9-diarylfluorene) as the active layer. Rather high luminance up to L ≈ 150 cd/m² and EL quantum efficiency up to η_ext ≈ 0.60% were achieved with the optimum source-drain channel length, indicating bipolar carrier injection in the terfluorene layer under the FET operation.