Methods and semiconductor materials produced by such methods that are suitable for use in photovoltaic cells, solar cells fabricated with such methods, and solar panels composed thereof. Such methods include a wet-chemical synthesis method capable of producing a Group I-III-VI2 semiconductor material by forming a solution containing an organic solvent, at least one Group I precursor of at least one Group I element, and at least one Group III precursor of at least one Group III element. The Group I precursor is present in the solution in an amount of less than 120% of a stoichiometric ratio of the Group I element in the Group I-III-VI2 semiconductor material, and the Group III precursor is present in the solution in an amount of greater than 55% of a stoichiometric ratio of the Group III element in the Group I-III-VI2 semiconductor material.