The advent of lead
halide perovskite nanocrystals (NCs), which
are easily synthesized, ultralow-cost materials and have an impeccable
luminous efficiency, has drastically changed the future perspective
of semiconductor quantum dot devices. Although the band gap energy
of lead perovskite NCs can be tuned by the halide composition, the
instability problem prevails for mixed-halide perovskite NCs, caused
by phase segregation due to ion migration when an external electric
field or light is applied. To avoid this problem and obtain the stable
emission of RGB primary colors, in this study, two synthesis pathways
of pure-halide perovskite NCs are proposed. One approach is the modified
hot injection method with “centrifugation of a frozen eutectic
mixture” to separate small NCs efficiently, and the other is
the “low-temperature mixing and heat-up method” for
target materials including CsPbI3, CsPbBr3,
and CH(NH2)2PbBr3 (FAPbBr3). The emission wavelength of FAPbBr3 is tuned ion-stoichiometrically,
unlike Cs perovskites. These various synthesis pathways of pure-halide
perovskite NCs enable the efficient production of high-quality perovskite
NCs and allow precise tuning of the emission color to the desired
wavelength. Although there are still several “gaps”
remaining in the available emission wavelength, the new methodology
proposed in this study could potentially be employed for manufacturing
more stable perovskite NC-based optoelectronic devices.