A Directed Route to Colloidal Nanoparticle Synthesis of the Copper Selenophosphate Cu3 PSe4.

The first colloidal nanoparticle synthesis of the copper selenophosphate Cu3 PSe4 , a promising new material for photovoltaics, is reported. Because the formation of binary copper selenide impurities seemed to form more readily, two approaches were developed to install phosphorus bonds directly: 1) the synthesis of molecular P4 Se3 and subsequent reaction with a copper precursor, (P-Se)+Cu, and 2) the synthesis of copper phosphide, Cu3 P, nanoparticles and subsequent reaction with a selenium precursor, (Cu-P)+Se. The isolation and purification of Cu3 P nanoparticles and subsequent selenization yielded phase-pure Cu3 PSe4 . Solvent effects and Se precursor reactivities were elucidated and were key to understanding the final reaction conditions.