https://doi.org/10.1140/epjp/s13360-026-07499-7
Regular Article
Theoretical investigation of phenoxazine-based D–π–A sensitizers: cooperative effects of donor engineering and BF₂ incorporation on photophysical and photovoltaic properties
Xinjiang Key Laboratory for Luminescence Minerals and Optical Functional Materials, School of Physics and Electronic Engineering, Xinjiang Normal University, 830054, Urumqi, Xinjiang, China
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Received:
30
October
2025
Accepted:
24
February
2026
Published online:
24
March
2026
Abstract
The rational molecular design of donor–π–acceptor (D–π–A) organic dyes plays a pivotal role in improving the photovoltaic efficiency of dye-sensitized solar cells (DSSCs). In this study, a series of phenoxazine-based dyes incorporating isoindigo π-bridges and rhodanine acceptors was systematically investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The influence of donor substituents and BF₂ incorporation on the geometric structures, frontier molecular orbitals (FMOs), electrostatic potential (ESP) distributions, and charge-transfer characteristics was comprehensively examined. Theoretical analyses reveal that electron-donating substituents enhance intramolecular charge transfer (ICT) and light-harvesting capability, while the electron-withdrawing BF₂ group effectively stabilizes the lowest unoccupied molecular orbital (LUMO) level and broadens absorption. The resulting reduction in recombination energy and favorable energy alignment promote spontaneous electron injection from the excited dyes into the TiO₂ conduction band. Among the investigated systems, the dye Cʹ exhibits the strongest ICT, the highest light capture efficiency, and the optimal photovoltaic performance parameters by introducing a strong electron-donating group-OCH3 into the phenoxazine donor and simultaneously introducing BF2 at the acceptor. These findings provide valuable insight into the structure–property relationships of phenoxazine-based sensitizers and offer design guidelines for developing high-performance, metal-free dyes for next-generation DSSCs. This study represents the first systematic comparison of phenoxazine-based dyes featuring both donor engineering and BF₂ incorporation.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjp/s13360-026-07499-7.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
