RESUMO
In the context of progress towards the organic laser diode, we experimentally investigate the optical and electrical optimization of an OLED in a vertical λ/2 microcavity. The microcavity consists of a quarter-wavelength TiO2/SiO2 multilayer mirror, a half-wavelength-thick OLED and a semitransparent aluminum cathode. The Alq3/DCM2 guest-host system is used as the emitting layer. This study focuses on the design and the fabrication of a half-wavelength thick organic hetero-structure exhibiting a high current density despite both the thickness increase and the cathode thickness reduction. The emission wavelength, the line-width narrowing and the current-density are studied as a function of two key parameters: the hetero-structure optical thickness and the aluminum cathode thickness. The experimental results show that a 125 nm thick cavity OLED ended by a 20 nm thick aluminum cathode exhibits a resonance at 606 nm with a full width at half maximum of 11 nm, and with current-densities exceeding 0.5 A/cm². We show that even without a top high-quality-mirror the incomplete microcavity λ/2 OLED hetero-structure exhibits a clear modification of the spontaneous emission at normal incidence.
RESUMO
The quality factor of microcavity organic lasers, designed for operation under electric pumping, has been numerically investigated. The microcavity structure consists of an organic light emitting diode set in between multilayer dielectric mirrors centered for an emission at 620 nm. In order to optimize the quality factor, different parameters have been studied: the impact of high and low index materials used for the multilayer mirrors, the role of a spacer inserted in between the mirrors to obtain an extended cavity, and the effect of an absorbing electrode made of metallic or transparent conductive oxide layer. The results of our different optimizations have shown a quality factor (Q) as high as 15,000.