SmartKem Ltd. (Manchester, England) has announced a monolithic microLED display made using organic thin-film transistors (OTFTs).
It is reported that SmartKem’s method of laying down an OTFT backplane on top of gallium nitride LEDs has the potential to accelerate the commercialization of microLED displays.
The company, which was acquired by SmartKem Inc. in a reverse takeover transaction in February 2021, raised $24.6 million by that mechanism and is now traded on the over-the-counter (OTC) stock market in New York.
MicroLEDs are being touted as the next technology for displays because they promise high brightness, lower power and with longer lifetimes than mainstream alternatives in use, such as LCD and OLED. This is particularly important for portable powered displays such as smartwatches and augmented-reality/virtual-reality (AR/VR) displays that cannot accommodate large batteries.
Existing VR and AR headsets use liquid-crystal displays (LCD) and organic light-emitting diode (OLED) displays, which lack brightness, resolution, power efficiency and lifetime.
Efforts to establish microLED manufacturing typically use physical transfer of individual LEDs from the wafer upon which they are manufactured to the TFT display backplane, where they must be laser welded to the contact pad of the transistor to make an electrical connection.
In high resolution displays this produces yield and repair issues and this is one factor that has slowed down the commercialization of microLEDs, according to SmartKem.
SmartKem’s approach is to use semiconductor inks that can be processed at the low temperature of 80°C directly on top of the microLEDs. This eliminates the mass transfer and laser welding processes, and the fabrication of OTFTs can use existing low-cost manufacturing tools currently used for LCD backplane manufacturing.