Theoretical Characterization of Photoactive Molecular Systems Based on BODIPY-Derivatives for the Design of Organic Solar Cells

Abstract

To search for high-efficiency narrow-band donor materials to improve the short-circuit current density ($J_{sc}$) of organic solar cells, a series of small molecules based in Bodipy-Triphenylamine were characterized using density functional theory (DFT) and time-dependent (TD-DFT) calculations. According to the energy of the exciton driving force they have the appropriate energy levels to match \textbf{\textit{PC$_{61}$BM}}. The properties affecting the open circuit voltage ($V_{oc}$), $J_{sc}$ and the fill factor ($FF$) were investigated by calculating the geometric structures, the boundary molecular orbital energy levels, absorption spectra, light collection efficiencies, chare transfer rates, and exciton binding energies. The results show that the \textbf{\textit{BTPA~III}} system has a lower LUMO level, high absorption efficiency, and exction dissociation than other molecular systems, facilitating the improvement of $V_{oc}$, $J_{sc}$ and $FF$. Finally, \textbf{\textit{BTPA~III}} would be the most promising of this series of donors and further increase the efficiency of the device.