Molecular simulation of chlorophyll-a derivatives for biological pigment solar cells

ABSTRACTIn this study, various factors affecting the photon-to-electron conversion efficiency of chlorophyll-a derivatives were determined to improve the performance of biological pigment solar cells. By employing the density functional theory with hybrid exchange–correlation functional B3LYP, we calculated the photoelectronic properties such as energy gaps, main transmission path, electronegativity, proton affinity, spectral absorption, and electron transfer rates of chlorophyll-a derivatives, e.g. chlorin–Fe, chlorin–Mg, chlorin–Ni, and chlorin–Zn. The difference in electronegativity between the central metal and the adjacent nitrogen atoms induced changes in the distribution of electron clouds, which indirectly enhanced the absorbance in ultraviolet and long wavelength ranges; thus, the absorption spectrum can be controlled. Further, chlorin–Mg and chlorin–Ni demonstrated better electron transfer rates. The results indicate that design strategies of biopigment derivatives are an effective way to reduce...