Cluster Approach To Model Titanium Dioxide as Isolated or Organic Dye Sensitized Nanoobjects
Résumé
This paper proposes the cluster approach methodology to simulate electronic properties of semiconducting isolated nanocrystalline materials as well as functionalized by organic dye molecules. The proposed cluster approach considers the nanoobject construction with the crystal structure in the internal part while the surface is modified according to the environmental interaction. In this aim, the (TiO2)n clusters with n = 2-140, indoline dye molecule D102, and their hybrid composites were investigated. The electronic properties of (TiO2)n were computed thanks to different DFT potentials, considering the nanobject sizes evaluation, their environmental surface modification and saturation, and the interface effects occurring between the cluster and sensitizer. The studies prove that the electronic features of (TiO2)n nanoparticles with surface being altered by the external environment may be coherently computed using DFT methodology with LC-BLYP potential by modifying the long-range separation parameter μ. The values of μ depend on the composition of the investigated system, whereas the surface saturation of the studied clusters possessing suitable size did not have any critical impact on their electronic properties. It is shown that the developed methodology is also relevant to characterize the charge transfer involved in the hybrid forms associating dye molecules and (TiO2)n clusters. The mentioned process is crucial in the efficiency of photovoltaic devices based on the hybrid systems.