Optical and electrical properties of purpurin and alizarin complexone as sensitizers for dye-sensitized solar cells

The optical and electrical properties of two dyes purpurin (1,2,4-trihydroxy-9, 10-anthracenedione) and alizarin complexone (alizarin-3-methylimino-N,N-diacetic acid) as sensitizers for dye-sensitized solar cells were investigated by using UV–Vis spectrum, FT-IR spectrum, cyclic voltammetry and I–V (current–voltage) characteristics. In addition, electrochemical impedance spectroscopy was adopted to research the electrons transfer process between each interface of the dye-sensitized solar cell. For comparison with the experiments, the frontier molecular orbitals, vibration analysis, the total static first hyperpolarizability and driving force of electron injection were calculated by using density functional theory (DFT) with B3LYP, at 6-31G(d) basis set. Moreover, the transition properties were investigated by using time-dependent density functional theory (TD-DFT) with PBEPBE functional at 6-311+G(d,p) basis set in theory. The solvent effect and basis set effect were taken into consideration to investigate the excited state properties of the dyes. The results showed that alizarin complexone had a higher energy conversion efficiency of 0.27 % than that of purpurin (0.13 %), with higher open circuit voltage (\(V_{oc}\)) of 0.45 V, higher short circuit current density (\(I_{sc}\)) of 0.89 mA cm⁻² and higher fill factor (\({\text{ff}}\)) of 0.67, indicating that the photovoltaic characteristics of alizarin excelled that of purpurin.