Linearly arranged polytypic CZTSSe nanocrystals

Abstract

Even colloidal polytypic nanostructures show promising future in band-gap tuning and alignment, researches on them have been much less reported than the standard nano-heterostructures because of the difficulties involved in synthesis. Up to now, controlled synthesis of colloidal polytypic nanocrsytals has been only realized in II-VI tetrapod and octopod nanocrystals with branched configurations. Herein, we report a colloidal approach for synthesizing non-branched but linearly arranged polytypic I2-II-IV-VI4 nanocrystals, with a focus on polytypic non-stoichiometric Cu2ZnSnSxSe4−x nanocrystals. Each synthesized polytypic non-stoichiometric Cu2ZnSnSxSe4−x nanocrystal is consisted of two zinc blende-derived ends and one wurtzite-derived center part. The formation mechanism has been studied and the phase composition can be tuned through adjusting the reaction temperature, which brings a new band-gap tuning approach to Cu2ZnSnSxSe4-x nanocrystals.

Heterovalent Substitution to Enrich Electrical Conductivity in Cu2CdSn1-xGaxSe4 Series for High Thermoelectric Performances

“…The reported ZT values for pure polycrystalline are 0.19 for Cu 2 CdSnSe 4 and 0.18 for Cu 2 ZnSnSe 4 4. Many efforts have been done to enhance the TE performance of these quaternary compounds by doping1467891011 and nanocrystalling3512131415161718. Nanocrystallization is an effective way to reduce the thermal conductivity, but the complex chemical procedure is not suitable for large scale production in commercial applications.…”

A Route to Phase Controllable Cu2ZnSn(S1−xSex)4 Nanocrystals with Tunable Energy Bands

“…Cu 2 ZnSn(S 1−x Se x ) 4 (CZTSSe, 0 ≤ x ≤ 1), composed of earth-abundant and nontoxic elements, have received much attention due to their potential applications in solar cells, electrocatalysts, and thermoelectricity12345678910. For many of these applications, it is important to synthesize pure-phased nanocrystals with tunable bandgap, and experimentally determine the band position.…”

“…CZTSSe nanocrystals with bandgap tunable from 1.0 to 1.5 eV have been synthesized using octadecene as solvent23. Up to now, synthesis of CZTSSe nanocrystals by the colloid chemical method has generally adopted oleylamine (OLA) as the main solvent3102223. OLA is indeed a benchmark solvent for synthesizing uniform, monodispersed, and phase pure nanocrystals ranging from metals to various semiconductors.…”

Structural Properties

“…[69]. [84] at the (112), (200), (220), (312), (008), and (332) planes of the kesterite-type CZTS lattice. ; (b-e) From supplementary information in Ref.…”

“…The structural properties of nanocrystalline Cu 2 -II-IV-VI 4 solid solutions have been reported for Cu 2 Zn x Cd 1−x SnS 4 [85], t-Cu 2 ZnGe x Sn 1−x S 4 [86], CZTSSe [57,84,[87][88][89][90][91][92], and Cu 2 CdSn(S x Se 1−x ) 4 [93]. Ramasamy et al [85] obtained WZ-phase Cu 2 Zn x Cd 1−x SnS 4 nanorods over the entire composition range by a facile solution method.…”