Transferable, flexible white light-emitting diodes of GaN p–n junction microcrystals fabricated by remote epitaxy

Highlights: • Transferable, flexible white light-emitting diode (WLED) is demonstrated via remote epitaxy of GaN p–n junction microcrystals (μCs). • The WLED is reliably operated in repetitive bending deformation and thermal shock cycling tests. • Matrix arrays of WLED were easily assembled by transfer–printing method owing to excellent transferability endowed from remote epitaxy. The remote epitaxy of GaN p–n homojunction microcrystals (μCs) is demonstrated for fabricating transferable, flexible white light-emitting diodes (WLEDs). The GaN p–n junction μCs are randomly grown on graphene-coated Al₂O₃(0001), which are then delaminated for mass-transfer onto conducting copper tape. The μCs-LED shows electrical rectification and white electroluminescence (EL) emission. The μCs-WLED exhibits reliable LED performances after repetitive bending deformations and cycling temperature environments. Based on the transferability, the μCs-WLEDs are patterned and assembled to matrix arrays, which exhibit homogeneous, reliable performances even at a bent form. We discuss that the origin of white EL emission is mixing of blue and yellow–red EL emissions from p-GaN and n-GaN sides, respectively, based on photoluminescence spectroscopic measurements. This study opens a way of fabricating the transferable, flexible, and modular light panels through remote epitaxy.