Electrochemical properties and performance of the pulsed laser deposited CZTS counter electrode-based DSSCs

In this article, we report the growth of Cu 2 ZnSnS 4 (CZTS) films using a pulsed-laser deposition technique, to use as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). A pulsed Nd-YAG laser in third harmonic generation (wavelength: 266 nm; pulse width: 9 ns and pulse frequency: 5 Hz) was used to ablate CZTS target. The ablated CZTS material was deposited on fluorine-doped tin oxide-coated glass substrate kept at 200°C under the vacuum of 6×10 –6 mbar followed by annealing at 500°C to obtain CZTS films. Detailed characterization of the CZTS films was performed using X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The ablation of the CZTS target by 1000 laser pulses (energy: 200 mJ) was found to result in the formation of a well-crystalline CZTS with characteristic weak and strong Raman modes at 287 and 337 cm –1 . The CZTS films with different thicknesses were prepared by varying the number of laser pulses. Thickness-dependent electrocatalytic ability and electrochemical properties of the CZTS CEs were studied by cyclic voltammeter, electrochemical impedance spectroscopy and Tafel polarization. The thickness-dependent performance of DSSCs made with CZTS CEs was measured through J – V characterization. The DSSC based on CZTS CEs deposited with the thickness ~ 225 nm (ablated with 1000 laser pulses) showed maximum power conversion efficiency of 3.98%. The results indicated the potentiality of CZTS to replace Pt CE (5.53%) in DSSCs.