Synthesis and Characterization of CuZnSe₂ Nanocrystals in Wurtzite, Zinc Blende, and Core–Shell Polytypes

Abstract

CuZnSe2 (CZSe) is an important ternary semiconductor comprised of earth-abundant elements with a suitable bandgap for visible light absorption and structural/stoichiometric versatility that make it a promising candidate for photovoltaic applications. Here we report the controlled synthesis of the compound copper chalcogenide in nanocrystal form using a colloidal hot injection approach. Furthermore, we demonstrate control over the crystal phase to occur as either wurtzite (WZ) or zinc blende (ZB) as a function of the presence and absence of phosphine-based ligands. A major emission peak was observed at ∼1.7 eV using low-temperature photoluminescence (PL), ranging from 30 to 200 K. Additionally, we demonstrate the ability to extend this synthetic protocol to form a polytype structure comprised of a ZB core with a WZ shell.

Growth of Multinary Copper-Based Sulfide Shells on CuInSe2 Nanocrystals for Significant Improvement of Their Near-Infrared Emission

“…Instead of depositing binary ZnS or ZnSe shells on CISe NCs, ternary CuInS 2 (CIS) shells were also constructed via multistep cation exchange reactions, starting from CdSe/CdS core/shell nanostructures. , The growth of ternary copper-based compounds on CISe NCs may provide a chance to further improve PLQY because of the similar metal elements in the core and the shell. Very recently, ternary CIS or CuZnSe 2 shells with wurtzite (WZ) crystal structure were deposited on cubic CIS or CuZnSe 2 core NCs, respectively, forming core/shell NCs consisting of the same compound but with a different crystal structure. Those polytypic CIS core/shell NCs showed the optical behavior typical for type-II core/shell structures, and the PLQY of the heterophased CIS NCs was only around 2% .…”

Phase-Controlled Growth of CuInS2 Shells to Realize Colloidal CuInSe2/CuInS2 Core/Shell Nanostructures

“…CdSe/CdS core/shell NCs with cubic zinc-blende (ZB) core and hexagonal wurtzite (WZ) shells were separately reported by Mahler and Ghosh. , Compared to CdSe/CdS core/shell NCs with identical crystal structure for both core and shell, in polytypic CdSe/CdS core/shell NCs a thick WZ CdS shell could efficiently suppress fluorescence blinking . Very recently, polytypic copper-based ternary compounds were reported, such as CIS and CuZnSe 2 (CZSe) NCs. After formation of a CIS or CZSe core with a cubic chalcopyrite (CP) or ZB crystal structure, the same material with a different crystal structure was further grown to form cubic CP/hexagonal WZ CIS NCs or cubic ZB/hexagonal WZ CZSe core/shell NCs.…”

Optical Properties and Electronic Structure of Copper Zinc Sulfide Nanocrystals

“…CZS NCs were synthesized using a colloidal chemical approach. The methodology adopted here is essentially similar to the one adopted for the synthesis of copper–cadmium–zinc selenide materials , and relies on rapid kinetics to avoid the formation of undesirable copper sulfide phases. The synthetic details are given in Supporting Information (section 1).…”