Computational analysis of charge transfer and optoelectronic properties in triphenylamine-based molecules for high-efficiency organic solar cells

Abstract

The global energy landscape is undergoing a profound transformation, driven by the urgent need to address environmental concerns and energy security. In recent years, alternative solar energy technologies have attracted increasing interest and investment, and organic solar cells (OSCs) have emerged as promising alternatives to traditional silicon-based solar cells. In this study, a series of four Mi donor materials (i = 1-4) incorporating triphenylamine with donor-acceptor-acceptor (D-A-A) configurations was developed. These materials were designed by modifying the acceptor portion of the reference molecule TPA-R by incorporating four different fragments containing sulfur heterocycles, selenophene, and thiadiazole. The electronic and optical properties of small electron donor materials (SEDMs) were explored through theoretical analysis using density functional theory (DFT) simulations at the B3LYP/def2-SVP level of theory to optimize the geometrical structures and the TD-CAM-B3LYP/6-31G(d,p) approach to predict the excitation behavior. The theoretical results were then compared with experimental data, revealing a high degree of agreement. All the designed compounds, M1-M4, showed prominent and broad absorption peaks in the visible spectra, ranging from 595 to 726 nm, with comparatively smaller energy gaps (E_g) than the reference TPA-R. Excited-state analysis revealed that all the designed molecules exhibited a significantly high electron-hole transfer rate from the D moiety to the second A2 acceptor, indicating that modification of the first acceptor improves the charge transfer properties. To fully understand how the small donor molecules interact with the C70 acceptor, molecular dynamics (MD) was performed.

Keywords

Organics solar cells / DFT / Molecular dynamics / Charge transfer / Triphenylamine

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Mohammed Elkabous: Writing - review & editing, Writing - original draft, Visualization, Validation, Software, Resources, Methodology, Investigation, Conceptualization. Mohammed Ouachekradi: Writing - review & editing, Writing - original draft, Visualization, Validation, Investigation, Conceptualization. Yasser Karzazi: Writing - review & editing, Writing - original draft, Visualization, Validation, Supervision, Investigation, Conceptualization.

Acknowledgements

We gratefully acknowledge the support of the Center for Doctoral Studies (CEDOC) at University Mohammed I. We also extend our sincere gratitude to the reviewers for their valuable comments and suggestions, which have significantly enhanced the clarity and scientific rigor of this study.

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