White-Light Generation and OLED Lifetime Issues.

Abstract

This thesis presents experimental results and discussion regarding issues related to organic light-emitting devices (OLEDs). In particular, this thesis has three main focuses: the generation of white light from Förster transfer in blends of emissive polymer and methods used to characterize the efficiency of that transfer; low temperature, conformal, thin film encapsulation for organic devices; and the effect of a pulsed driving scheme on the lifetime of OLEDs. In the first research focus, a method is proposed to measure the efficiency of Förster energy transfer. The efficiency of Förster transfer has previously been studied in biological systems, but this thesis presents a method which may be used for systems of semiconducting polymers. In addition, this thesis presents a theoretical basis for comparing the efficiency of a Förster-blend-based white light emitter to a similar emitter with no Förster energy transfer in order to show that white light generation from Förster transfer does, indeed, increase emission efficiency. The latter two research efforts examine the effect of encapsulation and driving scheme on the growth rate of non-emissive dark regions in OLEDs and, as such, share similar experimental apparatus. The formation and growth of non-emissive dark regions have been a persistent problem in OLED fabrication. The results presented in this thesis show that the combination of proper encapsulation and driving method can effectively slow the growth of these non-emissive regions.