Synthesis and characterization of Cs2Sn1-xCuxCl6 and Zn1-yMyO (M=Cu, Co) for perovskite solar cell applications

Abstract

A Photovoltaic cell (PVC) is a device that can convert light energy to electricity continuously without any required heat engine. A third-generation (organic/inorganic halide) PVC with Perovskite absorption layer (PAL) becomes a favorable material because of its high efficiency. An inorganic perovskite with a Cs2SnCl6 structure shows better stability, which can solve the short lifetime limitation (instability) of the cell. But a wide bandgap structured (low photo-luminescence) property of this perovskite materials makes it less efficient. In this work Cs2Sn1-xCuxCl6 (where x=0, 0.1, 0.15, 0.2 and 0.25) PAL and Zn1-yMyO (where M=Co and Cu, y=0.00, 0.01, 0.02, 0.03 and 0.05) Electron Transport Layer (ETL) was synthesized, followed by characterizations. The phase purity was analyzed by X-ray diffraction (XRD), where the PAL showed a phase pure and cubic with a space group of Fm3m. Moreover, un doped and doped ZnO ETL showed a phase pure with Wurtzite and hexagonal crystal structure. Morphology and elemental analysis of both PAL and ETL were analyzed with Scanning Electro-Microscope (SEM) and Energy Dispersion X-ray Spectroscopy (EDS). UV vis and Photo-Luminescence spectroscopy (PL-spectroscopy) were used for the optical property characterizations of the PAL, showing a decrease in the bandgap energy from 4.19 eV of Cs2SnCl6 to 3.47 eV for Cs2Sn1-xCuXCl6 (x=0.20). Moreover, analysis of the bandgap energy of the PAL by PL spectroscopy showed a decreasing value, where a new peak formed confirming the decrease in the bandgap. Furthermore, the optical bandgap energy of un doped and doped ZnO ETL showed a decrease in bandgap from 3.24 eV of pure ZnO to 3.06 eV, and 3.19 eV for Co-doped ZnO (Co-Z2), and Cu-doped ZnO (Cu-Z2) respectively. The Current density-voltage (J–V) measurements were performed to analyze the doping effect of ZnO ETL on Cs2Sn1-xCuXCl6 (x=0.20) PAL device, which showed a decreasing current density as the concentration of dopant increased, and a better current measurement value was obtained for Co-doped ZnO compared to that of Cu-doped ZnO ETL.