As an extra benefit, the positive turn-on voltage of the top-gated TFT can maintain the OFF state of the pixel without the supply of an additional gate bias voltage, reducing unnecessary power consumption during selective pixel operation.
To prove their novel MoS2 TFT architecture, the researchers then fabricated a backplane circuit for a flexible OLED display, consisting of a 6x6 array of transistors switching OLED pixels ON and OFF on a 6μm-thick ultrathin polyethylene terephthalate (PET) substrate.
After it was peeled from the carrier glass substrate, the ultra-thin active-matrix OLED display, only seven micrometers thick, exhibited stable performance during continuous operation even when affixed to the skin of a human wrist. Switching between the alphanumeric characters “M,” “O,” “S,” and “2”, the display was also driven under flexure at a repeated bending radius of 0.7mm, only suffering minor current variations (within 10%), which recovered when display was laid flat again.
The OLED was driven at approximately 8V while 9V were applied to the gate and drain terminals of the driving TFT. At VGate of 9V, the OLED pixels reached a maximum luminance of 408 cd m−2 and could be switched ON and OFF in milliseconds.
Next, the researchers will investigate if their novel transistor can be manufactured economically at scale for use in a high-resolution devices.
Yonsei University - www.yonsei.ac.kr
Chung-Ang University - https://neweng.cau.ac.kr