White light emission with tuneable colour temperature and high colour rendering index from CdS/Si multi-interface nanoheterojunctions

CdS/Si multi-interface nanoheterojunctions (CdS/Si-NPA) were fabricated by depositing CdS nanocrystallites (nc-CdS) on silicon nanoporous pillar arrays (Si-NPA) by chemical bath deposition. White electroluminescence (EL) with a high colour rendering index from a prototypical light emitting diode based on CdS/Si-NPA has been reported, which does not need complex colour mixing or conversion techniques. The white EL can be composed into three primary colours, which include blue emissions from the Si-NPA, the green emissions from the bandgap emission of nc-CdS and red emissions from the defects in the nc-CdS. Through the annealing treatment, the chromaticity coordinate and correlated colour temperature can be tuned. This indicates that CdS/Si-NPA is a potential candidate in the one-chip white LEDs.