In this paper

the characteristics of the transfer charge and the brightness andluminous efficiency on the applied voltage are investigated.Accelerating action of SiO

2

in thin film electroluminescence(TFEL) is proved directly.By accelerating of SiO

2

abrighter red TFEL device with low threshold voltage and good

B

-

V

charater is obtianed.

Q

-

V

charater of the samples with or without CdS are compared.We find that thetransfer charge of the samples with CdS is larger than that of the samples without CdS.This indicates that CdS layer can provide more electrons.The threshold voltage of the samples with CdS is low

and the highest luminescent intensity appears at lower vol tage.At the same voltage

however

the luminescence of the sample without CdS just begins to grow up.The luminous efficiency is lower in case of sample with CdS between ZnS and SiO

2

.This is attributed to the effect that after entering into the phosphor layer

the energy of these electrons is redused.When CdS layer is put between SiO

2

and electrode

the luminescent intensity and efficiency are increased in 2.5 and 0.5 orders

respectively.The electrons coming from CdS are accelerated obviously in SiO

2

.