Theoretical Design of Asymmetrical 5,10‐Diphenyl‐5,10‐Dihydrophenazine Donor– π –Acceptor Chromophores for Photovoltaic Applications

In this article, new organic dyes are designed by incorporating various π ‐spacers with the pyrazine donor moiety, resulting in novel chromophores ( P1 – P6 ). These π ‐spacers enhance the push–pull effect, achieving maximum absorption ( λ max ) of up to 989 nm, which exceeds that of the donor moiety. Ground‐state geometries are optimized using density functional theory (DFT) at the B3LYP/6‐31G + G (d,p) level, yielding near‐planar structures with dihedral angles of 0.50°–1.03°. Excited‐state properties are calculated via time‐dependent DFT (TD‐DFT) with the CAM‐B3LYP functional, validated against experimental benchmarks to ensure accuracy in predicting absorption spectra. The findings indicate excellent chemical stability and suggest that these switches are suitable for electron–hole‐overlap applications. Charge distribution patterns from frontier molecular orbitals demonstrate significant charge transfer involvement. The open‐circuit voltage ( V oc ) ranges from 1.58 to 4.71 eV, while the short‐circuit current ( J sc ) spans 20.36 to 81.79 mA cm −2 . Natural bond orbital analysis highlights transitions involving electronegative donor units, with stabilization energies reaching 50 kcal mol −1 . This research exemplifies the effective design of organic dyes for photovoltaic systems by utilizing appropriate π ‐spacers alongside donor and acceptor architectures.