Synthesis, characterization and emission tuning of I-III-VI2 semiconductor nanocrystals as color converting alternatives for white LEDs

Abstract

Colloidal I-III-VI2 semiconductor nanocrystals form a versatile family of nanomaterials with similar properties as Cd-containing quantum dots (QDs), but with lower toxicity. Their interesting and tunable optical properties have resulted in their use in a variety of applications, ranging from biolabeling over solar cells to white LEDs. For an optimal performance each of these applications requires the QDs to show specific optical properties. The relatively narrow emission of Cd-based QDs can easily be tuned over the visible range at a high chemical yield by adjusting specific synthesis conditions[1,2]. However, the typical broad emission of Cu-In-Zn-S QDs has proven to be more challenging to tune and requires a different strategy. We propose a study on the one-pot synthesis and characterization of Cu-In-Zn-S QDs with efficient and broad emission. A careful preparation of the precursors and control of the reaction time is required to synthesize CuInS2 and Cu-In-Zn-S QDs reproducibly. We discuss the limited emission tuning obtained by changing reaction conditions (e.g. precursor concentrations). More successfully, we have expanded the emission range by composition tuning, where In can for instance be replaced by Ga or Al and Cu by Ag. Finally, we address the potential of the resulting materials as alternative color convertors for white LEDs[3]. 1) S. Abe et al., ACS Nano, 2012, 6, 42. 2) S. Abe et al., ACS Nano, 2013, 7, 943. 3) P.F. Smet et al, J. Electrochem. Soc., 2011, 158, R3