Transcript A Mechanistic Study of Monomer Formation in the Synthesis of II
A Mechanistic Study of Monomer Formation in the Synthesis of II-VI Semiconductor Nanoparticles Jonathan S. Owen, Haitao Liu, and A. Paul Alivisatos Univ. of California- Berkeley and Lawerence Livermore National Lab kTHERM Cd(CH3)2 kPROT Cd0 + TOPSe CdSe + TOP Thermal Pathway + 2 H2-ODPA - 2 CH4 Se + Cd(ODPA-H)2 P R R R Cd(ODPA-H)2 O Se CdSe + + P P R R R R R R O O C18H37 P O P C18H37 OH OH Protolytic Pathway Multiple chemical pathways convert cadmium and selenium precursors into monomeric units of semiconductor that then nucleate and crystallize into nanometer scale particles. In order to better control particle growth kinetics we have uncovered the dominant chemical mechanisms that govern monomer formation. Shown above are the thermal and protolytic mechanisms that operate when alkylcadmium and phosphine selenides are used as particle precursors. The relative rates of the thermal and protolytic pathways impact the extant of nucleation at early reaction times and can be used to control the final particle concentration and size.