Low-Voltage, Low-Power Organic Light-Emitting Transistors for AMOLED Displays
M. A. McCarthy,1,2 B. Liu,1 E. P. Donoghue,1 I. Kravchenko,3 D. Y. Kim,2 F. So,2 and A. G. Rinzler1
1-Department of Physics, University of Florida, Gainesville, FL 32611
2-Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611
3-Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37830
Organic light-emitting diode (OLED) layers have been integrated into the carbon nanotube-vertical field effect transistor (CN-VFET) stack to create a highly efficient light-emitting transistor dubbed a CN-VOLET. It has been demonstrated that the light in each of the 3 primary colors is emitted through the 98% transparent nanotube source electrode. Conventional designs place the drive transistor next to the OLED. That limits the fraction of the pixel area available to the light-emitting OLED, requiring that it be driven harder, which limits the device lifetime. By integrating the drive transistor and the OLED within the CN-VOLET, the light emitter occupies a larger fraction of the pixel area, allowing lower current density for comparable light output, benefiting device longevity.
The CN-VOLETs demonstrated operate at voltages and power dissipation comparable to the AMOLEDs presently in handheld devices that use polycrystalline silicon in the backplane transistors. Such comparable efficiency is a first for an organic channel material (enabled by the CN-VOLET design) which could also provide the long sought after solution to the homogeneity problem plaguing polycrystalline silicon, and presently limiting OLED displays to small hand-helds.
This work is web-published by Science, 29 April 2011, DOI: 10.1126/science.1203052. The authors acknowledge support from the NSF (ECCS-0824157) and Nanoholdings, LLC., and UF Nanoscale Research Facility for use of equipment and technical support. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Office of Basic Energy Sciences, U.S. Department of Energy. DNTT was supplied by K. Takimiya (Hiroshima Univ.) and E. Kanoh of the Nippon Kayaku Co., Ltd.