Synthesis and characterization of CuInS2 single source precursors for chemical vapor deposition

A family of single source precursors, for the spray chemical vapor deposition (CVD) of chalcopyrite thin films (CuInS2), has been synthesized in good yields (ca. 65%). Newly synthesized compounds include [{L}2Cu(SR)2In(SR)2], (R=alkyl, aryl; L=neutral donor ligand). The use of the single source precursors provides an attractive alternative over conventionally used multi-source precursors, which are often toxic, air sensitive and pyrophoric. However, it is desirable that these thin films be processed on flexible polymer substrates such as KaptonTM. Therefore, milder deposition temperatures are needed to maintain the structural integrity of the underlying polymer substrates. By selective manipulation of the steric and electronic properties of the precursor, milder processing temperatures may be employed, while mainting the desired stoichiometry of the deposited films. Elucidation of the structures have been confirmed by the use of NMR. Thermal analytical techniques, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), have been employed to determine thermal profiles of each candidate compound.