Efficient down-conversion ZnO codoped (Er, Yb) nano powders synthesized via sol-gel process for Si solar cell applications

This study presents ZnO nano powders codoped by (Er, Yb) prepared by the sol-gel process using the supercritical drying of ethanol and then annealed at 500 degree C, 800 degree C and 1000 degree C. The molar percentage of Yb was fixed at 5%, and different molar percentages (5% and 10%) of Er at different temperatures were investigated. The structural and morphological studies show that the nano powders are crystallized in a wurtzite ZnO structure and that the grain size is around 60 nm. The variation of the annealing temperature and the doping percentage have a significant effect on the morphology and the crystallinity of the nano powders. Down-conversion emissions were investigated under 378 nm excitation and the (Er, Yb) codoped ZnO nano powders exhibit interesting emissions in the green, red, and infrared ranges