Current-Voltage Characteristics and Luminescence Spectrum of Organic Light Emitting Devices at Different Temperature

In this thesis, organic light emitted diode (OLED) is investigated the difference of spectrum at different temperature. First, we change the devices’ doping concentration, observing the tendency of OLED’s current density, luminance, efficiency and spectrum with doping concentration variation. Our organic device has two categories: red fluorescent device and blue phosphorescent device. By way of the relationship between device’s doping concentration and the slopes of J-V double log plot, we can predict the characteristic of these types of organic device, like exciton recombination mechanism, energy transfer mechanism and radiation process. General speaking, different types of organic device has different sensitivity of temperature because of their distinct radiation mechanism.
In fluorescent devices, it is considered that the absorption and radiation efficiency of host and dopant material and energy transfer efficiency will be affected at different temperature. In phosphorescent devices, which doping concentration is much higher than fluorescent devices, the variation of luminescence spectrum is unobvious at different temperature.