Color tunable electroluminescence from Co-doped ZnO nanorods/p-Si heterojunction

•ZnO: Co NRs/p-Si heterojunction has been synthesized by a simple chemical route.•The device shows good nonlinear rectifying behavior with a turn on voltage of 4 V.•Electroluminescence spectra show strong UV emission and broad visible emission.•The dominant peak changes to ultraviolet region with inject current increase.•With inject current increase, a red shift in visible emission is also observed.

Co-doped ZnO nanorods (ZnO: Co NRs)/p-Si heterojunction has been synthesized by a simple chemical route combine with sol-gel and hydrothermal methods. The structure analysis shows that the ZnO: Co NRs have wurtzite structures without any second phase, the Co ions successfully substitute Zn site in ZnO lattices. Room temperature ferromagnetism of ZnO: Co NRs is observed. The ZnO: Co NRs/p-Si heterojunction shows good nonlinear rectifying behavior with a turn on voltage of 4 V. Room-temperature electroluminescence (EL) spectra shows strong near band edge emission and defect related broad visible emission. With inject current increases, the dominant emission peak changes from visible to ultraviolet (UV). A red shift in visible emission is observed, this is ascribed to the doping effect of Co ions.