NOVELTY - The method of forming a photovoltaic device comprising a semiconductor layer, comprises forming the semiconductor layer by electrodeposition from an electrolyte solution. The electrolyte solution comprises 10% of 0.001-0.010 moles of the cupric sulfate per liter of the solution, 10% of 0.005-0.050 moles of the indium sulfate per liter of the solution, 10% of 0.005-0.050 moles of the gallium sulfate per liter of the solution, 10% of 0.005-0.050 moles of the selenous acid per liter of the solution and a chelating agent, and has a temperature of 25-90 degrees C.    USE - The method is useful for forming a photovoltaic device such as solar cell.    ADVANTAGE - The method is capable of economically and efficiently forming a solar cell with increased bandgap of the semiconductor material and improved light energy to electrical energy conversion efficiency.    DETAILED DESCRIPTION - The method of forming a photovoltaic device comprising a semiconductor layer, comprises forming the semiconductor layer by electrodeposition from an electrolyte solution. The electrolyte solution comprises 10% of 0.001-0.010 moles of the cupric sulfate per liter of the solution, 10% of 0.005-0.050 moles of the indium sulfate per liter of the solution, 10% of 0.005-0.050 moles of the gallium sulfate per liter of the solution, 10% of 0.005-0.050 moles of the selenous acid per liter of the solution and a chelating agent, and has a temperature of 25-90 degrees C. The pH of the electrolyte solution is 2.5, lower than 2.5 or higher than 9, and set by addition of sulfuric acid to the electrolyte solution. The electro-deposition comprises application of a deposition current between a substrate (160) upon which a material is deposited and a reference electrode, where a magnitude of the current is 4.5-20 mA/cm2 of the deposited material and a magnitude of the potential is 900 mV. The electrolyte solution further comprises 10% of 0.2 moles of trisodium citrate per liter of the electrolyte solution, a solution of methanesulfonic acid and water and 10% of 2 moles of the sodium hydroxide per liter of the solution of the sodium hydroxide and the water, where one of a compound comprising the copper, a compound comprising the indium, a compound comprising the gallium and the selenous acid are dissolved in the electrolyte solution comprising the solution of the methanesulfonic acid and the water or a solution comprising sodium hydroxide and water. The solution of the sodium hydroxide and the water assists in dissolution of the compound comprising the indium, the compound comprising the gallium and the selenous acid. The semiconductor layer comprises copper indium di-selenide comprising the copper and the indium, and all copper comprised in the semiconductor layer is comprised in the copper indium di-selenide. The semiconductor layer comprises a semiconductor compound having a composition represented as CuInxGa(1-x)Se2, where Cu is copper, In is indium, Ga is gallium and Se is selenium, and if: x is 1, the semiconductor compound comprises copper indium de-selenide; x is 0, the semiconductor compound comprises copper gallium de-selenide; and x is 0-1, the semiconductor compound comprises copper indium gallium di-selenide. The hydrogen formation is suppressed by adding a sulfinic compound, a sulfonic compound, a sulfinic acid, a sulfonic acid, sodium monohydrogen phthalate, monosodium phosphate, glycine, barbital, mannitol, sorbitol, amines, imidazoles, polymers and other organic additive, to the electrolyte solution. The electrolyte solution further comprises sorbitol at a concentration of 0.050 of a mole of the sorbitol per liter of the electrolyte solution to 1 mole of the sorbitol per liter of the electrolyte solution. INDEPENDENT CLAIMS are included for:    (1) a photovoltaic device;    (2) a method of forming a semiconductor compound; and    (3) a chemical solution.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a solar cell comprising copper indium gallium di-selenide.    Solar cell (100)    Third semiconductor layer (110)    Second semiconductor layer (130)    First semiconductor layer (140)    Back contact (150)    Substrate. (160)