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 optoelectronic applications such as organic lasers and light-emitting organic field-effect transistors (LE-OFETs). The oligo(9,9diarylfluorene) derivatives have high photoluminescence quantum efficiencies up to Phi(PL) approximate to 70-75% and very low amplified spontaneous emission thresholds (E-th) down to 0.5 AJ/cm(2) in their vacuum-deposited neat films. In particular, the trimer derivatives (B3 and T3) show higher PL and lower Eth than those of the dimers (B2 and T2). Efficient deep-blue LE-OFETs with the electroluminescence (EL) peaking at lambda(peak) = 429 nm were demonstrated using the ter(9,9-diarylfluorene) as the active layer. Rather high luminance up to L approximate to 150 cd/m(2) and EL quantum efficiency up to eta(ext) approximate to 0.60% were achieved with the optimum source-drain channel length, indicating bipolar carrier injection in the terfluorene layer under the FET operation.