title: Reduced threshold of optically pumped amplified spontaneous emission and narrow line-width electroluminescence at cutoff wavelength from bilayer organic waveguide devices.
abstract: We present a detailed study of the optically and electrically pumped emission in the BSB-Cz/PVK bilayer waveguide devices. By optical pumping we demonstrate that PVK as a spacer between fluorescent BSB-Cz and ITO electrode allows the significant reduction of the threshold for amplified spontaneous emission (ASE) of BSB-Cz. The simulation provides a better understanding of how the PVK thickness affects the waveguide mode field distribution and hence the ASE threshold of BSB-Cz. On the other hand, the BSB-Cz/PVK bilayer OLED exhibits the external quantum efficiency of >1% and anisotropic electroluminescence with spectrally narrowed edge emission at the cutoff wavelength controlled by the BSB-Cz thickness. When tuning the cutoff wavelength to match the peak gain of BSB-Cz, we demonstrate an intense, particularly narrow edge emission (~5 nm) without obvious degradation of efficiency at a high current density of 1000 mA/cm2, suggesting a reliable device performance for high-power applications and further exploration of electrically-pumped ASE.
authors.forename: Jui-Fen
authors.initials: JF
authors.lastname: Chang
authors.forename: Yu-Syuan
authors.initials: YS
authors.lastname: Huang
authors.forename: Po-Ting
authors.initials: PT
authors.lastname: Chen
authors.forename: Ruei-Lin
authors.initials: RL
authors.lastname: Kao
authors.forename: Xuan-You
authors.initials: XY
authors.lastname: Lai
authors.forename: Chii-Chang
authors.initials: CC
authors.lastname: Chen
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Lee