| AVS 55th International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF-ThA |
| Session: | Thin Films for Displays and Flexible Electronics |
| Presenter: | R. Ma, Universal Display Corporation |
| Authors: | R. Ma, Universal Display Corporation M. Hack, Universal Display Corporation J. Brown, Universal Display Corporation |
| Correspondent: | Click to Email |
In this paper, after a brief review of the history and current status of flexible displays and electronics, we will discuss in detail the development of one of the most challenging devices, a flexible full color active matrix organic light emitting diode (OLED) display. We will focus in the three areas: ultra-thin flexible TFT backplanes, rugged thin film barrier protection, and the flexibility of the overall system. The use of flexible substrates generates two main challenges: the handling of the flexible substrates and the compatibility of TFT process to substrate property. Both semiconductor and TFT-LCD industries are built on rigid substrates so the traditional process can’t be applied directly to flexible substrates. Mis-match of thermal properties between substrates and TFT materials/process will result failed backplanes. We have chosen thin metal foils as the substrates for flexible displays because of their excellent thermal, mechanical and permeation barrier properties and good flexibility. Metal foils as thin as 25 mm have been used and planarization process has been developed. Another key challenge is to develop a flexible thin film permeation barrier. OLEDs degrade as a result of exposure to atmospheric oxygen and water. Working with Professor Wagner’s team at Princeton University, we have identified a flexible, highly impermeable barrier layer that is deposited from environmentally-friendly and inexpensive precursors in a single-chamber reactor. The lifetime of OLEDs encapsulated with the layers exceeds the industrial target of 1,000 hours and also the lifetime of conventionally sealed glass packaged OLEDs. Many materials are used in a flexible AMOLED: organic, inorganic and metallic systems. We have studied the characteristics of such materials and developed an initial system to study the mechanical flexibility of the integrated device. We will present the required material building block properties and present recent results on ultra-thin (< 50 μm) flexible OLED displays. Flexibility results on these displays show that they operate when conformed to a tight diameter of only 5 mm.