CsCu2I3 Nanocrystals: Growth and Structural Evolution for Tunable Light Emission.

ABSTRACT

CsCu2I3 mixed with Cs3Cu2I5 has shown potential applications as white-light-emitting materials, while their growth, structural evolution behaviors, and their impact on photoluminescence of CsCu2I3 nanocrystals (NCs) are still not known. In this work, we investigated the growth and structural evolution of CsCu2I3 nanocrystals with increasing reaction temperature. At low temperature and in the presence of a high dosage of oleic acid and oleylamine, Cs3Cu2I5 nanoparticles, rather than CsCu2I3 NCs, preferred to form in the hot-injection reaction system. Increasing the reaction temperature promoted the formation of CsCu2I3 nanorods. Phase-pure CsCu2I3 nanorods were steadily obtained at 180 °C. Structural evolution from less copper-containing NCs to copper-rich ones in the low-temperature reaction condition is highly related to the coordination of copper ions with OAm. More importantly, accompanying the growth of nanorods and structural evolution from Cu3Cs2I5 to CsCu2I3, the color of photoluminescence emission of NCs changed from blue to nearly white and to yellow, but their photoluminescence quantum yield decreased from 36.00 to 9.86%. The finding in this work would give a view to the structural evolution of copper-containing perovskite-like halides, being helpful for adjusting their photoluminescence in white LEDs.