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 Φ PL ≈ 70-75% and very low amplified spontaneous emission thresholds (E th ) down to 0.5 µJ/cm 2 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/m 2 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.