Microwave Initiated Nucleation for the Synthesis of High Quality Nanocrystalline Quantum Dot Materials

K-J Kim, C-H Chang, P.M. Haben, D.A. Peterson, T.E. Novet, D.M. Schut
Shoei Electronic Materials, Inc., US

Keywords: nanoparticle, synthesis, quantum dots


The colloidal synthesis of nanoparticles, specifically quantum dots, may occur through either a kinetically dominated process where nucleation proceeds rapidly followed by growth via coalescence of nucleates to form larger nanoparticles, or through a thermodynamically dominated process in which nucleation occurs at high temperatures followed by epitaxial growth of the nanoparticle at lower temperatures via step-wise addition of precursors to the surface of the nucleates. Either process may be used for the production of a large variety of binary quantum dot materials such as CdX, PbX (X = S, Se, and/or Te), GaY, and InY (Y = P, As, and/or Sb). However, problems arise when forming quantum dots of ternary (or greater, multinary) compositions due to differences in the rate of nucleate formation during the synthesis – forming heterogeneous or multi-phasic materials. To address this issue, we are using microwave based chemistries to control the rates of nucleation of each of the components through specific microwave enhanced reactions. Through these methods we have been able to show the formation of homogeneous ternary compounds, such as CuInSe2, by enhancing the rate of nucleation of a thermodynamically dominated step to match that of a kinetically dominated step. By this manner, we enable the formation of homogeneous multinary quantum dot materials with an unprecedented degree of control.