Super flexible GaN light emitting diodes using microscale pyramid arrays through laser lift-off and dual transfer.

We demonstrated a method to obtain super flexible LEDs, based on high quality pyramid arrays grown directly on sapphire substrates. Laser lift-off (LLO) and dual transfer processes were applied to transfer pyramid arrays face up onto the flexible substrates, which is more efficient than back light emission. Ag grid and Ag nanowires were employed as the electrical connection. No significant performance reduction appeared until the device reached a curvature radius of 0.5 mm. The performance reduction results from cracks appearing at the junction of the Ag grid, which can be improved by replacing the Ag grid with a strip electrode.