Comparison between Benzothiadizole–Thiophene- and Benzothiadizole–Furan-Based D–A−π–A Dyes Applied in Dye-Sensitized Solar Cells: Experimental and Theoretical Insights

Abstract

Three novel donor–acceptor−π–acceptor-type compounds (WS5, WS6, and WS7) were synthesized and investigated in dye-sensitized solar cells (DSSCs) exploring the effect of conjugated linkers on device performance. The new dyes showed strong light-harvesting ability in the visible region with relatively high molar absorption coefficients (>21 800 M –1 cm –1 ). This can be attributed to their intrinsic charge transfer (CT) from the arylamine to the acceptor group. Density functional theory (DFT) calculations revealed a favorable lowest unoccupied molecular orbital (LUMO) energy level, allowing efficient injection into the semiconductor conduction band after excitation. Upon application in DSSC devices, the WS5 dye containing 4,7-di(furan-2-yl)benzo[ c ][1,2,5]thiadiazole as conjugated linker mediated the highest device power conversion efficiency (PCE) amounting to 5.5%. This is higher than that of the WS6-containing dye based on the 4,7-di(thiophen-2-yl)benzo[ c ][1,2,5]thiadiazole linker (3.5%) and the WS7 dye based on the 4-(thiophen-2-yl)benzo[ c ][1,2,5]thiadiazole linker (4.3%) under AM 1.5 G illumination. The present results show furan-based dye linker systems to have a significant potential for improving DSSC efficiencies.

Benzothiadiazole-based photosensitizers for efficient and stable dye-sensitized solar cells and 8.7% efficiency semi-transparent mini-modules

“…S1 in ESI †) that using a furan spacer, a higher degree of planarity along the molecule is achieved. 34 The dihedral angle of 20 between the benzothiadiazole unit and the phenyl in YKP-88 is reduced to 0 between the benzothiadiazole unit and the furan in DJ-214, leading to a perfect co-planarity and a better conjugation with the anchoring function. The introduction of the furan unit also induces the emergence of an absorption shoulder between 400-450 nm.…”

A Theoretical Evaluation of the Efficiencies of Metal-Free 1,3,4-Oxadiazole Dye-Sensitized Solar Cells: Insights From Electron-Hole Separation Distance Analysis.

“…where a large ∆𝐺 𝑑𝑦𝑒 𝑟𝑒𝑔𝑒𝑛 can promote dye regeneration and increase the J SC [22,45]. As O4 displayed the highest ∆𝐺 𝑑𝑦𝑒 𝑟𝑒𝑔𝑒𝑛 , its photoelectrons will be more easily regenerated.…”

Novel Dyes Design Based on First Principles and the Prediction of Energy Conversion Efficiencies of Dye-Sensitized Solar Cells

“…Zhu et al proposed a new concept, D–A−π–A dye, a highly efficient and stable organic sensitizer . This structure is not only the optimization of the energy-level structure, absorption spectrum, and photovoltaic performance of the DSSCs but also greatly improves the light stability of the dye . The Gratzel’s team designed a new series of co-receptors and demonstrated the important role of some co-receptors.…”

“…32 This structure is not only the optimization of the energy-level structure, absorption spectrum, and photovoltaic performance of the DSSCs but also greatly improves the light stability of the dye. 33 The Gratzel's team designed a new series of co-receptors and demonstrated the important role of some co-receptors. Liu et al also found that, in the same case, the D−D−π−A-type dye molecules have better advantages than the D−π−A dye molecules: the absorption spectrum extends to the longwavelength region, the molar absorption coefficient increases, and the thermal stability is better.…”