Theoretical Study On Phenothiazine Derivatives For Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have been considered as a promising alternative forenergy harvesting in order to solve the energy crisis as well as other environmental problems.Most organic dyes have a rod-shape configuration, and they are inclined to form aggregateson the semiconductor surface, leading to lower photovoltaic performance. Phenothiazine(PTZ), with electron-rich nitrogen and sulfur heteroatoms, has a high electron-donating ability.It also has a ring with a nonplanar butterfly conformation that can inhibit molecularaggregation. Therefore, in this work, we studied a series of sensitizers based on phenothiazineunder density functional theory (DFT) and time-dependent functional theory (TDDFT). Themain results are summarized as follows:1. Different functional should be selected to calculate the adsorption spectrum forvarious phenothiazine dyes when use time-dependent functional theory. The long-rangecorrected functional CAM-B3LYP and hybrid functional M06should be used for species IIand III phenothiazine dyes, respectively.2. The LUMO orbital of rhodanine-3-acetic acid moiety is isolated from the–COOHanchoring group, although the acceptor can decrease the HOMO-LUMO gap of dyes andincrease the photoabsorption ability, comparing to the dyes with cyanoacrylic acid. Therefore,it has better to use cyanoacrylic acid as the electron acceptor nad anchoring group forphenothiazine dyes.3. The designed new molecule (PTZ-pyrone-1) is promising and effective dye sensitizerfor dye-sensitized solar cells, comparing to the synthetic dyes, according to the calculatedmolecular geometry, frontier molecular orbitals and UV-Vis adsorption spectrum.