Patent ID: 8318050

Claim:
A method for making a precursor compound comprising: a) providing monomer compounds selected from the group consisting of (i), (ii), (iii) and (iv), wherein (i) is M B1 (ER) 3 , M B2 (ER) 3 , and M B3 (ER) 3 , (ii) is M B1 (ER) 3 and M B3 (ER) 3 , (iii) is M B2 (ER) 3 and M B3 (ER) 3 , and (iv) is M B3 (ER) 3 ; b) providing monomer compounds M A1 (ER) and/or M A2 (ER); and c) contacting the monomer compounds; wherein M B1 is In, M B2 is Ga, M B3 is Al, M A1 is Cu, and M A2 is Ag, each E is S, Se, or Te, and each R is independently selected, for each occurrence, from alkyl, aryl, heteroaryl, alkenyl, amido, silyl, and inorganic and organic ligands, the compound comprising repeating units {M B (ER)(ER)} and {M A (ER)(ER)}, wherein M B is M B1 , M B2 or M B3 and M A is M A1 or M A2 .