A carregar...
Publicação
Fabrication of Highly Reflective Bottom Electrodes for Inverted Top-emission OLED Applications
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 2.64 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
The demand for more air-stable and high resolution devices are opening the space for inverted top-emission OLEDs in the displays market. To realize these high-performance devices, a combination of a highly reflective bottom electrode with an efficient electron injection layer is essential to achieve high luminance efficiency and low driving voltage, respectively.
The aim of this thesis was to develop a new highly reflective stack and a corresponding method for high resolution patterning to enable future top-emission iOLED applications. First, the deposition methods for a multilayer reflective stack were developed. Initially, a structure using silver as reflective thin film and ITZO as electron injection layer was used. Reflective and transmission measurements together with optical simulation were executed to optimize the thickness of each sputtered thin film in the final stack. During the development, the oxidation of Ag prevented the high reflectivity of the layer. To mitigate this issue, a new stack with an ITO interlayer between Ag and ITZO layers was created to prevent silver oxidation from the ITZO deposition process. Finally, optimized samples with a configuration of Ag(50 nm)/ITO(5 nm)/ITZO(80 nm) were demonstrated with a reflectivity > 78% in the visible range.
To obtain high resolution feature sizes on the developed stack, the photolithography recipe to pattern the multilayer stacks with resolution down to 5um was also developed. During this project, different liquid etchants were tested to pattern the structure in two wet-etching steps. The quality of the etch were analysed by atomic force microscope and optical microscope images. Images of individual ITZO layers demonstrated the importance of using Ti Prime before photoresist spin-coating to improve the quality of the etch. At the end, cross-sections of the full stack showed that well-defined hills and valleys were achieved when samples were dipped in 10% mixed acid etchant for 30sec at RT followed by a dip in 75% PWES solution for 5 sec at 45C.
Descrição
Palavras-chave
Inverted top-emission OLEDs reflective cathode electron injection sputtering photolithography wet etching