Facile synthesis of sulfide-based chalcogenide as hole-transporting materials for cost-effective efficient perovskite solar cells

Sulfide-based chalcogenide quaternary semiconductors Cu₂MSnS₄ where M = Zn, Mn, Ni and, Co have emerged as a promising material for photovoltaic application due to their opto-electrical properties, friendly environment and earth-abundant composition. Herein, we report on the surfactant-assisted, solvent-free, hydrothermal synthesis of Cu₂MSnS₄ (M = Zn, Mn, Ni, Co) nanoparticles and their application in photovoltaics as well. The kesterite and stannite crystal structure of the investigated compounds were confirmed by powder X-ray diffraction. Raman, Photoluminescence and UV–Vis reflectance spectroscopies were employed to study the lattice vibrational and the optical properties. High-resolution transmittance electron microscopy was performed to study the morphology of nanoparticles size, as well as the crystallinity of chalcogenide compounds. In the presence of Cu₂MSnS₄ with different divalent transition metal ions (M) = Mn²⁺, Co²⁺, Ni²⁺ and Zn²⁺ as a hole transport material, the perovskite-sensitized TiO₂ films showed power conversion efficiencies of 8.35, 6.24, 7.55 and 4.16%, respectively.