Rational design of triphenylamine–benzothiophene-based donor materials for enhanced photovoltaic performance in solar cells: a DFT study

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Chinese explanation / 中文解读

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Original abstract

Designing efficient solar cells is vital for addressing the growing global demand for clean energy. Among various approaches, donor–π–acceptor (D–π–A) systems have attracted significant attention due to their tunable optoelectronic properties. Triphenylamine–benzothiophene-based donor materials have emerged as promising candidates for organic photovoltaic devices, owing to their ability to achieve high power conversion efficiency. This design strategy overcomes key limitations such as inefficient charge transfer, poor energy level alignment, and weak molecular interactions—critical factors in enhancing the overall performance. A new series of molecules (Thy1–Thy8) incorporating triphenylamine (TPA) side chains, carbazole, and thiophene-benzothiophene-based acceptors are proposed. Thy3 is predicted to exhibit a PCE of 28%, significantly higher than the reference ThPCyAc (PCE = 22%). TD-DFT and DFT simulations predict frontier molecular orbitals (FMOs), density of the transition (DOS), transition density matrix (TDM), and charge transfer factors. The proposed molecules exhibit optoelectronic properties that are highly favorable for efficient hole-transport materials in perovskite solar cells, with energy gaps of 0.48–1.02 eV, absorption maxima up to 799 nm for Thy3, and exciton binding energies of 0.16–0.26 eV. Further, these donor molecules possess relatively large reorganization energies (λ e = 0.0058 − 0.1122 Eh, λ h = 0.0077 − 0.0092 Eh) and a high fill factor between 85% and 91%. Based on this work, Thy3 copolymer exhibits the best performance and can be recommended for future solar cells.

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