Recent progress on organic light emitting devices -OLED, Organic light emitting transistor and organic semiconductor laser

We review recent progress on organic light emitting devices. First, we mention an organic light emitting transistor which has lateral organic light-emitting diode structure that allowed field-effect transistor (FET) operation. This device configuration provides a novel organic light-emitting diode structure where the anode (source) and cathode (drain) electrodes are laterally arranged, providing us a chance to control EL intensity by changing the gate bias. We demonstrated that TPPy provides compatible transistor and EL characteristics. Further, we discuss on prospect on organic laser diodes. In particular, 4,4'-bis[(N-carbazole)styryl] biphenyl (BSB-Cz) demonstrated an extremely low ASE threshold of E_th=0.32±0.05μJ/cm ², which is the lowest threshold ever reported. We observed that the 6-wt%-BSB-Cz:CBP film has an ultimate photoluminescence quantum efficiency of φ_pL=100% and a short transient lifetime of τ_f=1. 0±0.1ns, leading to a large radiative decay rate of k_r= 1×10⁹ s^-1. We also discuss on possibility of the CW lasing.