TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The copper is present in form of copper trithiocarbonate complex ((CUCS3)-, Cu(L)2(CS3)-, where L is NH3 or solvent), or copper tetrasulfide complex. The complex counterions are chosen from ammonium cation, hydrazinium, and thermally instable cation. Preferred Process: When the metal complex contains indium and/or gallium or zinc, cations are complexed and stabilized by excess of trithiocarbonate and/or triselenocarbonate respectively in the molar ratio of 1:3 or more. The precursor solution is perculated with hydrogen sulfide or hydrogen selenide gas, respectively, to avoid precipitation of solids. The manufacture of precursor solution involves preparing a solution containing indium in complexed form or indium and/or gallium in complexed form by dissolving or suspending a respective indium salt and gallium salt, in a solvent, complexing cation(s) using trithiocarbonate (CS3)2- by adding ammonium trithiocarbonate in an equimolar ratio or an excess, and adding copper complex chosen from copper trithiocarbonate complex or copper tetrasulfide complex, to resultant solution, or preparing (a) a solution containing zinc in complexed form by dissolving or suspending a zinc salt in a solvent, complexing (b) cation(s) with an excess of trithiocarbonate (CS3)2- by adding ammonium trithiocarbonate, preparing a solution containing copper and tin each in complexed form chosen from trithiocarbonate or tetrasulfide complexes, or preparing separate copper and tin containing solutions, and mixing the solutions. The molar ratio of zinc and ammonium trithiocarbonate in step (a) is 1:3 or more. The precursor solution is heated for forming a p-type semiconductor layer comprising copper indium selenide, copper indium gallium selenide or copper zinc tin sulfide on an electrode of solar cell, during manufacture of solar cell.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The solvent is chosen from pyridine, dimethylformamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone, 1-methylimidazole and/or water, preferably pyridine or dimethylformamide.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The polysulfide is trisulfide ion or tetrasulfide ion.