Computational Screening of D-π-A Structured with Acceptor-Tuned Metal-Free Organic Dye Molecules for DSSCs

Abstract

Four metal-free carbazole-based acceptor-tuned organic molecules (denoted as CBa1–CBa4) based on electron-donor, [Formula: see text]-spacer and electron-acceptor (D-[Formula: see text]-A) for dye-sensitized solar cells (DSSCs) have been newly designed. The electronic structures, optical absorption ultraviolet-visible (UV–Vis) properties and photovoltaic (PV) parameters of CBa1–CBa4 dyes were computationally studied by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. These molecules were planned through chemical alterations of the acceptor group of a literature-based organic dye known as CB1 dye. The planning of CBa1–CBa4 dyes was to decrease the highest occupied molecular orbitals (HOMOs) and lowest unoccupied MOs (LUMOs) of the energy gap ([Formula: see text]) and to red-shift their UV–Vis response compared to CB1. This study was initially performed using the exchange correctional (XC) and long-range corrected (LC) with the computational ideal in the TD-DFT method significantly to get an accurate absorption wavelength for CB1. From the XC and LC results, CAM-B3LYP functional is better matched with CB1. So, further newly organic CBa1–CBa4 dyes UV–Vis spectra were followed by this method. According to DFT and TDDFT results, CBa1 and CBa2 molecules were found to have reduced HOMOs–LUMOs energy gap, longer UV–Vis spectra and faster charger transfer (CT) character compared to CB1. The conclusion recommends that the newly designed molecules are hopeful and appropriate for optoelectronic devices. Hence, the work predicts to support the new scheming carbazole-based molecules with the studied properties for synthetizing to DSSC applications.