Pentacene TFT driven AM OLED displays

Pentacene organic thin-film transistors (TFTs)-driven active matrix organic light-emitting diode (OLED) displays has been investigated. This letter addresses several process issues unique to this type of display which are important in achieving bright and uniform displays. A bottom contact structure was used to fabricate the pentacene TFT backplane. Polyvinyl alcohol and parylene were used to isolate the pentacene active layer and passivate the backplane. The low processing temperature may allow the use of polymeric substrates and lower cost processing. Uniform TFT performance is achieved with reasonably good mobility and on/off ratio on the backplane. The initial OLED display performance is also presented.

I. Introduction

There has been great deal of interest in and research on organic light-emitting diodes (OLEDs) because of the possibility of thinner, lighter, faster, and more power-efficient displays. Several active matrix OLED (AM OLED) displays have been demonstrated on both glass and polymeric substrates [1], [2]. To date, most AM OLED displays have used polysilicon or amorphous silicon thin film transistors (TFTs) as the active elements [3]. Pentacene organic thin film transistors (OTFTs), with performance comparable to those of a-Si:H, are of interest because of the possibility of reduced processing cost compared to a-Si:H and perhaps also roll-to-roll manufacturing. A small (8 × 8 pixel) pentacene TFT-driven OLED display has been demonstrated by Chuman [4], however, a range of issues including device passivation techniques and TFT uniformity, still need to be addressed. Fig. 1. Circuit schematic of pentacene TFT driven active matrix OLED pixel.