Efficient and stable organic DSSC sensitizers bearing quinacridone and furan moieties as a planar π-spacer

Abstract

In this work, three new quinacridone-based dyes containing a furan moiety (QA1–3) have been synthesized through simple synthetic routes for the application of dye-sensitized solar cells (DSSCs). Their absorption spectra, electrochemical, photovoltaic properties and the cell long-term stability have been extensively investigated. Electrochemical measurement data indicates that the tuning of the HOMO and LUMO energy levels can be conveniently realized by alternating the donor moiety. The theoretical calculations show that the dihedral angle between the quinacridone moiety and the furan ring is less than 1 degree, indicating excellent planarity between the two groups, which is beneficial for intramolecular charge transfer. All of these dyes performed as sensitizers for DSSCs tested under similar AM 1.5 experimental conditions, and a maximum solar energy to electricity conversion efficiency of 7.70% (J_sc = 13.25 mA cm⁻², V_oc = 804 mV, FF = 0.73) for the 20 mM chenodeoxycholic acid (CDCA) co-adsorbed DSSCs based on QA1 is obtained. Electrochemical impedance experiments indicate that the electron lifetime is improved by co-adsorption of CDCA, accounting for the significant improvement of V_oc. Most importantly, the long-term stability of the QA1–3-based DSSCs with ionic-liquid electrolytes under 1000 h light-soaking has been demonstrated.