New Silver(I) Complexes as Achromatic Sensitizers in Solar Cell Applications

The design, synthesis, and spectroscopic characterization of [Ag(P(o-C₆H₄OCH₃)₃)(NO₃)]₂ (1) and [Ag(P(o-C₆H₄OCH₃)₃)₂][NO₃] (2) were conducted to investigate the efficiency of the fabricated solar cell devices. The slow evaporation technique proved effective in growing the colorless crystals of the silver(I) complexes. Spectroscopic analyses including Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and ultraviolet–visible (UV–Vis) studies were carried out to elucidate the chemical structure and absorption properties of the compounds. The chemical composition and existence of intermolecular interactions in 1 and 2 were disclosed via the single-crystal x-ray diffraction method. The side-to-side arrangement of molecules in 1 and 2 was evident from the crystal packing analysis, in which the molecules in both compounds were linked together by C–H···O and C–H···π contacts. The silver(I) complexes exhibited maximum absorption wavelength (287–288 nm) within the ultraviolet region, where both compounds had comparable high energy band gap values ranging from 4.15 to 4.16 eV. Moreover, both compounds possess appropriate HOMO–LUMO energy levels that facilitate effective electron injection and dye regeneration processes in dye-sensitized solar cell (DSSC) applications. Photophysical characterization techniques, field-emission scanning electron microscopy (FESEM), and energy-dispersive x-ray (EDX) spectroscopy studies were employed to assess the morphological characteristics and elemental composition of the silver(I) complexes on TiO₂. Compound 2 exceeded 1 in terms of solar cell efficiency, 2 (η = 3.34%) > 1 (η = 0.66%) due to the complex being in ionic form and composed of the mononuclear [Ag(P(o-C₆H₄OCH₃)₃)₂]⁺ cation [NO₃]⁻ anion.