A strong green emission has been observed from Tb3+ doped GdOBr powder phosphors upon excitation with an UV- wavelength. TO such a bright green color display phosphor material, different amount of Ce3+ from 0.1 to 1 mol percent has been added to further improvise the green emission efficiency. It has ben found that 0.2 mol percent of Ce3+ is the optimum content which resulted in an enhancement in the green emission intensity by five or six times compared to that of the singly doped terbium phosphors. It has been noted that with the increment of Ce3+ concentration, green emission of Tb3+ could not increased due to the strengthening of Ce3+- Ce3+ ion interaction or the concentration quenching effect. The mechanism involved in the energy transfer between the Ce3+ and Tb3+ has been explained using the energy level diagram. Energy absorbed by the sensitized Ce3+ ions could be transferred to fluorescent Tb3+ ions by means of resonant energy transfer and this ins mainly due to dipole interaction.
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