Automatized colloidal particle synthesis for knowledge-based product design

• Applicants: Professor Dr.-Ing. Wolfgang Peukert; Professorin Dr.-Ing. Doris Segets
• Subject Area: Mechanical Process Engineering
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 281196640

Aim of this project is to establish a research platform for highly reproducible, automatized synthesis of quantum confined semiconductor nanoparticles (quantum dots, QDs) with fast sampling. QDs were chosen due to their novel and enhanced size-dependent opto-electronic properties which make them ideal candidates in the emerging fields of electronic devices and renewable energy. However, the controlled synthesis of smallest QDs follows elaborate protocols that require highly experienced experimentalists. Complex structure-property relationships are obtained where minimal deviations in the particle size distribution (PSD), deviations in the presence and composition of a surrounding inorganic shell or even deviations in the surface chemistry have maximum effects on the product properties (absorbance and emission).By means of automatization and rapid sampling the following points shall be covered: i) transfer of complex lab protocols to automatized workflows, ii) exclusion of the human factor to a maximum extend for superior reproducibility at demanding synthesis conditions, iii) establishment of important process-structure-property relationships, iv) fast and efficient screening of large parameter spaces for material development and v) extraction of kinetic parameters for a mechanistic understanding of particle formation. Addressing these aspects is necessary to get an unambiguous understanding at which steps within the process chain from small building blocks towards functional devices quality is lost and how new materials need to be designed and processed for optimum product properties.While the aim of the first funding period is the characterization of the system and the development of rational screening routines, the focus of the second funding period is determined by the development of routines for mechanistic investigations of particle formation processes including nucleation, growth and ripening. In this context, a reasonable high throughput (HT) post-processing in terms of purification and classification needs to be developed as well. Thus, HT particle synthesis will be established as a highly reliable approach for the determination of optimum synthesis protocols.Within the first funding period the following directions shall be followed: First, HT synthesis and HT characterization protocols for both, dispersity in terms of the PSD and product property in terms of the quantum yield (QY) shall be developed. In parallel, a reproducible sampling during early stages of particle formation (< 10 s) will be established. Then, a detailed investigation of the system characteristics in terms of heating and cooling profiles but also with respect to characteristic mixing times shall be realized. The latter are of major importance with respect to the last part of the first funding period where large parameter spaces will be efficiently screened and important process-structure as well as structure-property functions will be established.

• DFG Programme: Research Grants