Nanostructured p-CuIn3Se5/n-CdS heterojunction engineered using simple wet chemical approach at room temperature for photovoltaic application

Research highlights: → The Nanostructured p-CuIn3Se5/n-CdS heterojunction engineered using simple wet chemical approach at room temperature on glass substrates. → The interface, composition and surface can be well modified using the chemical ion exchange method to synthesize the heterojunction and post deposition treatment such as annealing at 200 deg. C. → The optical properties such as energy band gap observed at ∼1.4 eV which matches with the natural sun spectrum of AM 1.5 and the electrical properties including I-V analysis exhibits its use as an efficient material for solar cell applications. - Abstract: Herein, we report engineering of nanostructured p-CuIn3Se5/n-CdS heterojunction thin film on a glass substrate, which is prepared at room temperature using simple wet chemical approach involving ion exchange reactions between CdS and Cu+, In3+ and Se2- ions in alkaline medium. The uniform deposition of heterojunction thin films is achieved by optimizing the pH, temperature and molarity of the reactant bath. The as-deposited thin-films were annealed at 200 deg. C in air for 1 h and further characterized for structural, optical and electrical properties using UV-Vis spectrophotometer, X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Hall effect for type of conductivity, and I-V measurement to investigate the charge conduction phenomenon. The characteristic (1 1 2) and (1 1 0) planes in XRD and the electron diffraction pattern could confirm the formation of CuIn3Se5. The chemical composition and the band gap energy Eg = 1.4 eV of the nanostructured p-CuIn3Se5/n-CdS heterojunction thin-films were confirmed using XPS and the absorbance spectra, respectively. Based on the data and energy band gap calculations of CuIn3Se5 and CdS thin films, the probable band alignment between the nanostructured p-CuIn3Se5/n-CdS heterojunction is proposed.