Selective Phase Transformation of Wurtzite Cu₂ZnSn(SSe)₄ (CZTSSe) Nanocrystals into Zinc-Blende and Kesterite Phases by Solution and Solid State Transformations

Abstract

A wide range of physical properties from opto-electronic (e.g. band gap) to structural (e.g. hardness) can be affected without changing the composition of the solid but just by altering the crystal phase. Here, we report selective structural phase transition of metastable wurtzite CZTSSe nanocrystals into more stable phases such as zinc-blende and kesterite using solution and solid state transformations respectively. The phase transformation pathways are selective with the wurtzite-zinc blende transition not possible by thermal anneal or the wurtzite to kesterite by solution transformation. We show the importance of both ligand chemistry and temperature to lowering the barrier for rapid conversion from one phase to another in this system. The phase transitions are accompanied by changes in the band-gap with values for each calculated by cyclic voltammetry.

Solution-Based Synthesis and Characterization of Cu2ZnSnS4 (CZTS) Thin Films

“…In Figure 5, the X-ray diffraction (XRD) spectra of the samples treated at 200, 350, and 500 °C are shown, demonstrating that different CZTS phases formed. At TT 200 °C, a mix of cubic (distinctive peaks at 2θ = ~33.2°, ~38.5°, ~55.7°, and ~66.3°) and hexagonal, also known as wurtzite (at 2θ = ~31.4°, ~35.3°), CZTS phases formed [39]. At TT 350 °C, only cubic CZTS phase formed [40].…”

Synthesis of Colloidal WSe2 Nanocrystals: Polymorphism Control by Precursor-Ligand Chemistry

“…To obtain better control over the crystal phases, compositions, and stabilities of TMDs, low-cost bottom-up synthesis approaches based on colloidal chemistry have been investigated. − A few studies have also revealed the potential applications of the TMDs by a colloidal chemistry method. − With WSe 2 as an example, the 2H nanosheets synthesized by colloidal synthesis have shown promise as catalysts for the conversion of amines to imines. Colloidal 1T′ WSe 2 nanosheets, on the other hand, exhibit an enhanced electrocatalytic activity for hydrogen evolution in comparison to 2H WSe 2 .…”

Thickness optimization of the ZnO based TCO layer in a CZTSSe solar cell. Evolution of its performance with thickness when external temperature changes.

“…Watson, in 2013 obtained the best performances for CZTSSe based solar cells with power conversion efficiency equal to 12.6% [8,9]. Several research groups reported the growth and fabrication of CZTSSe solar cells using various methods such as sputtering followed sulfo-selenization [10,11], solution growth process [12,13], nano-particle approach [14,15], electrodeposition [16,17], ink jet printing [18], pulsed laser deposition [19,20], ball milling and hybrid ink followed by sulfoselenization [21,22].…”