Researchers from the University of Waterloo have demonstrated the successful integration of a-Si:H TFTs and high-efficiency micro-LED chips on large-area flexible substrates. This is the first time that an amorphous silicon was used to drive Micro-LEDs which could pave the way for lower-cost micro-LED display fabrication using existing LCD technology.

2T pixel circuit, before and after micro-LED transfer on a:SI (University of Waterloo, 2019)

the researchers use a 2-TFT pixel circuit, with blue GaN-based micro-LED chips. The low-temperature TFT production process enabled the direct integration onto a flexible flexible polyethylene naphthalate (PEN) substrate. After the TFT fabrication, the micro-LED chips were flip-chip bonded on the TFT, and then transferred onto the flexible pixel circuit using a selective laser lift-off process.

The researchers say that the selective laser liftoff process did not degrade the micro-LEDs in any way, and it enabled a 25% boost in electroluminescence due to a better light extraction.

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