Tunability of Photovoltaic Functions via Halogen Substitution [(Ade)₂ CdX₄](X = Cl, Br): A Class of Three-Dimensional Organic–Inorganic Hybrid Materials

Abstract

Two new three-dimensional organic–inorganic hybrid crystalline materials, [(Ade)2 CdCl4] (1) and [(Ade)2 CdBr4] (2), were obtained by the slow evaporation of adenine (Ade) and cadmium chloride in aqueous solution at room temperature with hydrochloric acid and hydrobromic acid used as halogen sources. The structural, thermal, optical, and electrical properties were characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, variable-temperature–variable-frequency dielectric constant analysis, and electrochemical tests. With increasing the substitution of Cl by Br, the composition of the material changed and the space group shifted from P-1 to P21/m, with a significant blue-shift in the fluorescence emission. Changing the temperature induced the deformation of the three-dimensional framework structure formed by hydrogen bonding interactions, leading to dielectric anomalies. Cyclic voltammetry tests showed the good reversibility of the electrolysis process. The structural diversity of the complexes was realized by modulating the halogen composition, and a new method for designing novel organic–inorganic hybrids with controllable photoelectric functionality was proposed.

Keywords

• metal halide
• three-dimensional framework
• photoluminescence
• dielectric
• electrochemical