Computational Molecular Design of New 3D Structured Quinoxaline Dyes With Panchromatic NIR Absorption and Enhanced Stability Enabling Efficient Copper-Based Dye Sensitized Solar Cells.

The development of panchromatic near-infrared (NIR) dyes with robust adsorption stability is crucial for enhancing the efficiency of copper-based dye-sensitized solar cells (Cu-DSSCs). By leveraging the champion dye ZS4 utilized in Cu-DSSCs, we have developed and theoretically investigated a range of dyes using DFT/TDDFT calculations, focusing on the interfacial electronic dynamics of dye@(TiO₂)₈₂. Our findings reveal that dyes incorporating pyrazino[2,3-g]quinoxaline groups, in place of the diphenylquinoxaline group in ZS4, exhibit significantly improved light-harvesting abilities. These dyes display an NIR absorption spectrum that spans the entire UV-visible range while extending into the NIR region. Notably, these dyes maintain intramolecular charge transfer characteristics comparable to ZS4, resulting in a maximum photocurrent density enhancement of 11.5 mA/cm². Furthermore, the use of heterocyclic anchoring groups instead of the cyanoacrylic acid group substantially increases the adsorption stability. By meticulously considering various factors influencing dye performance, we identified the pyrazino[2,3-g]quinoxaline-cyclopenta[1,2-b:5,4-b']dithiophene-2-(1,1-dicyanomethylene) combination as superior to the champion dye ZS4, thereby contributing to the improved efficiency and stability of Cu-DSSCs.