Combinatorial Synthesis of CdSe Nanoparticles Using Microreactors

Several microreactors combined with an online detector were used as a combinatorial synthesis system to optimize nanoparticle synthesis for rapid and flexible development of nanoparticles to meet various needs and applications. Three reaction parameters—temperature, reaction time, and reaction additive (dodecylamine) concentration—were combined systematically to produce synthesis condition sets (five points each, total of 125 points). The photoluminescence (PL) wavelength, PL quantum yield (PLQY), PL full width at half-maximum (PL fwhm), particle size, and product yield (PY) of the products were determined for each condition to obtain property data sets. The average time to complete all procedures to obtain one reaction condition per particle property data set was approximately 20 min. The reaction conditions were varied to provide a series of data sets meeting three specific objectives: (1) to seek condition sets producing superior properties, (2) to assess reaction condition effects on property data sets and elucidate their underlying mechanisms, and (3) to find reaction conditions meeting practical requirements for applications and achieve a balance of criteria. These objectives were met. High reproducibility verified the system reliability. Data set maps were used to determine the reaction conditions to produce high-QY particles (56%). These maps supported systematic assessment of the reaction condition effects on product properties. The data sets show agreement with formally reported findings related to QY dependence on particle size and CdSe deposition rate enhancement with amine concentration, thereby confirming the system reliability. Results also showed that high amine concentration suppressed the deposition rate. The maximum deposition rate of 5−10% indicated that these systems can be assessed quantitatively to achieve balanced conditions. Finally, by applying a weighting function to the data sets, a point of balance among properties was determined easily. This approach is effective for determination and selection of optimum conditions for practical applications.