Metallo-dithiaporphyrin pigments for bulk-heterojunction solar cell applications: ab initio investigation of structural and optoelectronic properties

Metallo-dithiaporphyrin small molecules have been designed by substituting Ru(ii) with various transition metals at the same oxidation state (M = Mn, Fe, Ni, Cu) as donor materials for Bulk Heterojunction Organic Solar Cells (BHJ-OSCs). Density functional theory (DFT) and time-dependent DFT (TD-DFT) have been used to study the optoelectronic properties of metallo-dithiaporphyrin at various functionals and basis sets. We discovered that the open-circuit voltage (VOC) value increases when Ru(ii) in Ru(S2TTP)Cl2 (S2TTP = tetra-p-tolyldithiaporphyrin) is substituted. In addition, the light harvesting efficiency (LHE) of nickel, manganese, and iron complexes was found to be similar to that of ruthenium, and the iron complex furthermore presented a comparable charge transfer in the excited state corresponding to the Q-band, compared to Ru(S2TTP)Cl2. Hence M(S2TTP)Cl2 (M = Mn, Fe, Ni) appear to be potential low cost candidate donor molecules within a bulk heterojunction solar cell. We further propose suitable engineered acceptor pigments, fitted to provide a good overall solar cell efficiency.

Solid state structure and properties of phenyl diketopyrrolopyrrole derivatives

Crystal structures of the title compounds show diverse packing by interactions of auxochromes giving materials with varied optoelectronic properties.

Theoretical study on the optical response behavior to hydrogen chloride gas of a series of Schiff-base-based star-shaped structures

Schiff-base compounds have many applications in the field of optoelectronic materials and chemical sensing because of their appealing coordination ability, and simple and easily accessible use in structural modification. Herein, five kinds of star-shaped Schiff-base compounds were designed and their optical response behavior to hydrogen chloride (HCl) gas was studied using dependent/time-dependent density functional theory (DFT/TDDFT). Moreover, the relationship between structures and properties was investigated upon changing the benzene group into N atom or triazine group at the core-position and introducing a methoxyl (-OCH₃) or nitro (-NO₂) group into the star-shaped Schiff-bases at the tail of the branches. The results show that all five Schiff-bases could be candidates for HCl gas sensing materials. Furthermore, introducing an electron-donating group at either the core or the tail forms a charge transfer channel with the electron deficient H-bonded imino group, which is convenient for charge transfer and subsequently promotes a red-shift in absorption spectra and fluorescence quenching.