Investigation of Indium Phosphide Nanocrystal Synthesis Using a High-Temperature and High-Pressure Continuous Flow Microreactor

摘要

Indium phosphide (InP) nanocrystals are of significant interest for use in optoelectronic devices, specifically as a replacement for CdSe nanocrystals in commercial applications. However, the current mechanistic understanding and synthetic procedures for InP nanocrystals has not yet reached the same level as for CdSe nanocrystal synthesis. Using a truly continuous three-stage microfluidic reactor to precisely tune reaction conditions in the mixing, aging, and sequential growth regimes, our study described here builds on previous InP nanocrystal synthetic and mechanistic work to probe the significant experimental parameters involved in InP nanocrystal syntheses. We find that the growth of InP nanocrystals is dominated by the aging regime, which is consistent with a model of InP nanocrystal growth where nanocrystal growth is dominated by nonmolecular processes such as coalescence from nonmolecular InP species and interparticle ripening processes. The InP growth model is in contrast to the molecular-based growth of nanocrystals as observed in CdSe and PbSe nanocrystals. We observe that the size of InP nanocrystals is predominantly dependent on the concentration of free fatty acid in solution and the aging temperature. Other experimental parameters such as injection temperature and particle concentration do not appear to significantly affect InP nanocrystal size or size distributions. In addition, we probe the ability to grow larger InP nanocrystals through the sequential injection of precursors in the third stage of the microfluidic reactor.