Organic light-emitting transistors with split-gate structure and PN-hetero-boundary carrier recombination sites

Novel light-emitting transistors (OLETs) with the split-gate electrode divided into two parts for independent control of electron and hole were devised, in addition to the PN-hetero-boundary combined with the electron and hole transport materials along carrier channels. With this device structure, the on/off ratio of 1000 or more in the current and the luminance were achieved. Which is 100 times or more large compared with earlier reported single-gate type PN-hetero-boundary light-emitting transistor [N. Suganuma, N. Shimoji, Y. Oku, K. Matsushige, Novel organic light-emitting transistors with PN-heteroboundary carrier recombination sites fabricated by lift-off patterning of organic semiconductor thin films, J. Mater. Res. 22 (2007) 2982; N. Suganuma, N. Shimoji, PCT Int. Appl. WO2007/010925; N. Suganuma, PCT Int. Appl. WO2007/026703]. In this device, the luminance of about 100 cd/m2 was obtained at 15 V in the source–source voltage (also known as the source–drain voltage) with the turn-on voltage of less than 10 V. The horizontal PN-hetero-boundary structure was implemented for the first time by using the photolithographic patterning of the organic semiconductor thin-films. This patterning technique can be applied in fabricating not only organic light-emitting transistors reported in this article but also organic integrated circuit or organic display.