Abstract
In this paper, we employ density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches to predict the solvatochromism and light-harvesting properties of a newly synthesized hybrid hexamine (HMTA) vanadium-substituted Lindqvist-type (V 2 W 4 ) polyoxometalate (POM), (C7H15N4O)2(C6H13N4)2[V2W4O19]·6H2O, (HMTA-V 2 W 4 ) for application in dye-sensitized solar cells (DSSCs). Single crystal X-ray diffraction (XRD) and noncovalent interaction (NCI) analyses show a 3D-supramolecular packing stabilized by means of hydrogen bonds and van der Waals (vdW) and ionic interactions between highly nucleophilic cage-like HMTA surfactant, lattice water, and electrophilic V 2 W 4 polyanions. Experimental and theoretical UV/vis absorption spectra show large absorption in the visible region, which is strongly solvent polarity dependent. This solvatochromic behavior can be attributed to hydrogen bonding interactions between the V 2 W 4 polyanion and protic solvents. Furthermore, the energy level of semiconductor-like nature of HMTA-V 2 W 4 with high LUMO level matches well with the conduction band (CB) of TiO2, which is beneficial for the photovoltaic device performance. The photovoltaic empirical parameters are theoretically predicted to demonstrate a remarkably high open-circuit voltage (Voc) value (1.805 eV) and a photoelectric conversion efficiency (PCE) value up to 8.7% (FF = 0.88) along with superior light-harvesting efficiency (LHE) (0.7921), and therefore, the studied compound is expected to be a potential candidate as a photosensitizer dye for applications in DSSCs. The aim of this work was to broaden the range of applications of POMs, owing to their low-cost fabrication, leveraging and flourishing optoelectronic properties, and ever-improving efficiency and stability for use in future technology pointed to the development of clean and green renewable energy sources to solve the current energy crisis.