Annealing and quenching are the most efficient ways for electroluminescent materials to improve their maitenance. The reason why annealed and quenched phosphor has a long lifetime is not yet clear.By making the investigations on the emission spectrum

thermoluminescence and ion probe

it is found for the first time that the distribution of copper in a phosphor particle is changed by annealing and quenching. The copper is concentrated in a small region near the surface during quenching

And these regions correspond to copper sulfide segregation. Therefore

the reason why the annealed and quenched phosphor has a long lifetime may be considered to be that the copper sulfide segregation is stabilized by annealing and quenching

and the ZnS-Cu

2

S junction is formed. The distribution of electric field in a particle must be stringly deformed and concentrated near the surface. The field strength and potential barrier are increased and the condition of initial electron injection is improved

Thus the degradation of ACEL phosphor is alleviated