Schottky Diode (SD) Al/a-Se/Au as a solar cell (SC) was prepared by thermal evaporation technique (TET) on glass thin slide as a substrate under vacuum (10!" mbar). The Schottky Barrier (SB) have been prepared with different thicknesses (300, 500 and 700) nm in room temperature and (343) K annealing temperature. The current-voltage (IV) physical properties of the SB have got rectification properties and approved as a SC. This cell is developed with increased annealing temperatures and thickness of layers of SD. Experience under lighting shows good efficiency (η), which increased linearly with both thickness and annealing temperatures from (0.0318% to 4.064%) and from (0.0318% to 0.4778%). This is for three values of lighting power density (160, 230, 400) 𝑚𝑊/𝑐𝑚# in which the behave is similar. The best efficiency obtained in this work was (15.286)% at a power density of 400 𝑚𝑊/𝑐𝑚# , with thickness 700nm and 343K annealing temperature. Also (12.407)% at 230 𝑚𝑊/𝑐𝑚#, with thickness 500nm for the same annealing temperature.