Among the advantages of multicomponent nanocrystals is the possibility to adjust their electronic and optical properties with composition as well as size. However, the synthesis of multicomponent nanocrystals is challenging due to the presence of several metal precursors in the reaction mixture. This review takes I-III-VI semiconductor materials as an example class of multicomponent nanocrystals to highlight the underestimated importance of composition, which can affect the electronic and optical properties of nanocrystals as much as size. We discuss synthetic strategies, which enable the composition control, and show that the ability to separately choose nanocrystal size and nanocrystal composition can be beneficial for many optoelectronic and bio-medical applications.

We report a facile colloidal synthesis of gallium (Ga) nanoparticles with the mean size tunable in the range of 12–46 nm and with excellent size distribution as small as 7–8%. When stored under ambient conditions, Ga nanoparticles remain stable for months due to the formation of native and passivating Ga-oxide layer (2–3 nm). The mechanism of Ga nanoparticles formation is elucidated using nuclear magnetic resonance spectroscopy and with molecular dynamics simulations. Size-dependent crystallization and melting of Ga nanoparticles in the temperature range of 98–298 K are studied with X-ray powder diffraction, specific heat measurements, transmission electron microscopy, and X-ray absorption spectroscopy. The results point to delta (δ)-Ga polymorph as a single low-temperature phase, while phase transition is characterized by the large hysteresis and by the large undercooling of crystallization and melting points down to 140–145 and 240–250 K, respectively. We have observed size-tunable plasmon resonance in the ultraviolet and visible spectral regions. We also report stable operation of Ga nanoparticles as anode material for Li-ion batteries with storage capacities of 600 mAh g^–1, 50% higher than those achieved for bulk Ga under identical testing conditions.