Fabrication and temperature-dependent photoluminescence spectra of Zn-Cu-In-S quaternary nanocrystals

A series of Zn-Cu-In-S nanocrystals (ZCIS NCs) are prepared and the optical properties of the ZCIS NCs are tuned by adjusting the reaction time. It is interesting to observe that the temperature-dependent photoluminescence (PL) spectra of the ZCIS NCs show a redshift with decreasing intensity at low temperature (50-280 K) and a blueshift at high temperature (318-403 K). The blueshift can be explained by the thermally active phonon-assisted tunneling from the excited states of the low-energy emission band to the excited states of the high-energy emission band.