Compositionally Tunable Photoluminescence Emission in Cu₂ZnSn(S_1−xSe_x)₄ Nanocrystals

Abstract

Inorganic nanostructures: Alloyed Cu2ZnSn(S1−xSex)4 wurtzite nanocrystals (10 nm in size) with a varying composition (x=0–1) were synthesized using a colloidal hot injection route. A photoluminescence (PL) emission study of these nanocrystals shows a compositionally tunable band‐gap ranging between 0.9–1.4 eV that directly correlates to the sulfur‐to‐selenium ratio (see picture).

Phase-transition-driven growth of compound semiconductor crystals from ordered metastable nanorods

“…The observed Raman peaks at 150 cm -1 , 260 cm -1 , 288 cm -1 , 338 cm -1 (A-mode), 366 cm -1 and 376 cm -1 (vertical lines in Fig. 5a) are in good agreement with peak positions earlier found for kesterite CZTS [43], while dominant modes at 334 cm -1 and 377cm -1 (arrows) of CZTS nanorods have been also reported for wurtzite CZTS [10,20]. The strongest A-mode symmetry of kesterite CZTS annealed samples shifts to lower frequency region and significantly broadens with decreasing heating rate as shown in the inset of Fig.…”

“…5b), indicating strong compensation, which has been found to be a necessary prerequisite for good solar cell performance in chalcopyrite as well as kesterite-based thin film solar cells [45][46][47]. The observed PL bands in CZTS annealed samples can be attributed to quasi donor acceptor recombination [10]. We do not find an obvious trend for the influence of the heating rate on the PL properties of the annealed CZTS films.…”

“…The signals of the annealed films at 150 cm -1 , 260 cm -1 , 288 cm -1 , 338 cm -1 (A-mode), 366 cm -1 and 376 cm -1 (vertical lines) can be attributed to kesterite [43]. The arrows at 334 cm -1 and 377cm -1 mark the positions of the wurtzite signals [10,20]. The inset shows peak position and full width at half maximum (FWHM) of the main kesterite peak (A-mode) as function of heating rate.…”

Alloyed Copper Chalcogenide Nanoplatelets via Partial Cation Exchange Reactions

“…, annealing of the NC-substrates, typically at 500 °C under Se vapors), 2,3,9,11 which leads to grain growth, and the replacement of sulfur by selenium resulted in the narrowing of the materials band gap from 1.5 eV for CZTS to 1 eV as calculated for CZTSe. 22 On the other hand, compositionally tunable low-temperature photoluminescence of Cu 2 ZnSn(S x Se 1– x ) 4 NCs has recently been demonstrated by Singh et al , 23 indicating their potential in photoemissive applications. Although even a multigram synthesis 24,25 and a continuous production 26 of CZTS nanoparticles in a flow reactor have already been developed, a significant control in terms of the size and shape is still not achievable by the direct synthesis for such complex quaternary materials, in contrast to well developed syntheses of binary semiconductor compounds (such as chalcogenides of zinc, cadmium, lead, mercury, as well as indium phosphide and arsenide).…”

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

“…7,8 In our area of interest, complex quaternary materials such as Cu2ZnSnS4 (CZTS), Cu2ZnSnSe4 (CZTSe) or Cu2ZnSn(SSe)4 (CZTSSe) have been synthesized in 0-D, 1-D and 2-D morphologies in wurtzite, kesterite and stannite crystal phases by judicious selection of ligands and precursors. [9][10][11][12][13][14][15] The first-principles total-energy calculations show that the wurtzite phase as derived from binary II-VI wurtzite structure features ABABAB stacking and is the least stable phase. 16,17 The kesterite structure derived from a binary II-VI zinc-blende structure having ABCABC stacking is the most stable crystallographic structure.…”