Synthesis and Behavior of Cetyltrimethyl Ammonium Bromide Stabilized Zn(1+x)SnO(3+x) (0 ≤ x ≤1) Nano-Crystallites

We report synthesis of cetyltrimethyl ammonium bromide (CTAB) stabilized Zn(1+x)SnO(3+x) (0 ≤ x ≤1) nano-crystallites by facile cost-effective wet chemistry route. The X-ray diffraction patterns of as-synthesized powders at the Zn/Sn ratio of 1 exhibited formation of ZnSn(OH)(6). Increasing the Zn/Sn ratio further resulted in the precipitation of an additional phase corresponding to Zn(OH)(2). The decomposition of these powders at 650°C for 3h led to the formation of the orthorhombic phase of ZnSnO(3) and tetragonal SnO(2)-type phase of Zn(2)SnO(4) at the Zn/Sn ratio of 1 and 2, respectively, with the formation of their mixed phases at intermediate compositions, i.e., at Zn/Sn ratio of 1.25, 1.50 and 1.75, respectively. The lattice parameters of orthorhombic and tetragonal phases were a ~ 3.6203 Å, b ~ 4.2646 Å and c ~ 12.8291Å (for ZnSnO(3)) and a = b ~ 5.0136 Å and c ~ 3.3055Å (for Zn(2)SnO(4)). The transmission electron micrographs revealed the formation of nano-crystallites with aspect ratio ~ 2; the length and thickness being 24, 13 nm (for ZnSnO(3)) and 47, 22 nm (for Zn(2)SnO(4)), respectively. The estimated direct bandgap values for the ZnSnO(3) and Zn(2)SnO(4) were found to be 4.21 eV and 4.12 eV, respectively. The ac conductivity values at room temperature (at 10 kHz) for the ZnSnO(3) and Zn(2)SnO(4) samples were 8.02 × 10(−8) Ω(-1) cm(-1) and 6.77 × 10(−8) Ω(-1) cm(-1), respectively. The relative permittivity was found to increase with increase in temperature, the room temperature values being 14.24 and 25.22 for the samples ZnSnO(3) and Zn(2)SnO(4), respectively. Both the samples, i.e., ZnSnO(3) and Zn(2)SnO(4), exhibited low values of loss tangent up to 300 K, the room temperature values being 0.89 and 0.72, respectively. A dye-sensitized solar cell has been fabricated using the optimized sample of zinc stannate photo-anode, i.e., Zn(2)SnO(4). The cyclic voltammetry revealed oxidation and reduction around 0.40 V (current density ~ 11.1 mA/cm(2)) and 0.57 V (current density– 11.7 mA/cm(2)) for Zn(2)SnO(4) photo-anode in presence of light.