Synthesis, Spectral, Electrochemical and Photovoltaic Studies of A₃B Porphyrinic Dyes having Peripheral Donors

Abstract

Three new 'push-pull' A 3 B Zn(II)porphyrin dyes having mesopyrenyl, carbazolyl and phenothiazine as electron donors (A) and phenylcarboxylic acid as acceptor/anchor (B) were synthesized and utilized for DSSC application. The spectral and electrochemical redox properties of these new dyes were studied and compared with trans-A 2 BC Zn(II) porphyrin dyes under similar experimental conditions. Red-shifted, broadened absorption peaks, lower fluorescence quantum yields, and shortened lifetimes were observed for the A 3 B dyes as compared to zinc tetraphenylporphyrin control, ZnTPP. DFT optimized structures suggested effective charge separation related to enhanced charge injection efficiency. Driving force for electron injection (ΔG inj ) and dye regeneration (ΔG reg ) calculated from the spectral and electrochemical studies predicted facile electron injection from excited dye into semiconductor TiO 2 in the constructed solar cells. Phenothiazine appended dye (KP-TriPTZ-Zn) showed the highest η value of 7.3 % for PCE with greater J sc and V oc values due to its better light harvesting ability and reduced dye aggregation as compared to other dyes. Our studies demonstrate that the dyes having multiple electron-donating groups exhibit higher photon-to-current conversion efficiency.[a] Dr.

Unraveling Structure–Performance Relationships in Porphyrin-Sensitized TiO2 Photocatalysts

“…This change in distribution probably arose from the steric volume of the phenothiazine donor moieties, resulting in larger dihedral angles in respect to the macrocycle and, hence, in a better charge separation. These results were also confirmed by other authors who used phenothiazine derivatives as strong donor substituents [ 100 , 101 , 102 ]. Along these lines, Hu et al prepared a series of β-functionalized push–pull dibenzoporphyrins with different arylamine substituents as the donor groups ( Figure 24 ) [ 101 ].…”

Fluorenyl Indoline as an Efficient Electron Donor for Concerted Companion Dyes: Enhanced Light-Harvesting and Photocurrent

“…Since the first sensitizers were reported in 1991, a variety of efficient photosensitizers like polypyridyl ruthenium­(II) dyes, − metal-free organic dyes, − and porphyrin dyes − have been reported. Inspired by the fact that natural porphyrins (i.e., chlorophylls, bacteriochlorophylls) are the pigments to utilize solar energy, artificial porphyrin dyes featured with intense absorption, excellent redox, and facile structural modification have been developed as efficient sensitizers. − To enhance the light-harvesting capability, various strategies in terms of incorporating π-extended chromophores, ,,− fusing the peripheral positions of porphyrin with aromatic units, ,, and employing hydroporphyrins have been developed. However, the valley of the absorption spectra in the green light region still limits its further development.…”

Study of the microscopic mechanism of stepwise charge injection in co-sensitive DSSCs in the framework of a D–π–A dye and chlorophyll

“…25 The C, H, O and N atoms have been optimized at the B3LYP/ 6-31G(d) level, and Ti atoms have been optimized at the B3LYP/ LANL2DZ level. [26][27][28][29] The solvation model density (SMD) method was used to simulate the tetrahydrofuran solvent environment. 30,31 The structures of charged molecules were further optimized; chemical reaction parameters, such as electron affinity (EA) and chemical hardness (h), were obtained.…”