A plasma display panel with first and second substrates facing each other, and address electrodes formed on the second substrate. A partition wall is disposed between the first and the second substrates to separately partition a plurality of discharge cells. A phosphor layer is formed within each discharge cell. Discharge sustain electrodes are formed on the first substrate. A thickness of the phosphor layer is designed so that the resulting internal space has a shape corresponding to the diffusion shape of the plasma discharge generated within the discharge cell to optimize brightness of the image and to maximize light emission efficiency.