Novel quinoline-based sensitizers coupled with diethylenetriamine as a new co-adsorbent to improve photovoltaic performance of dye-sensitized solar cells

Abstract

Two novel metal-free dyes with 2-ethylhexyloxy substituted triphenylamine as the donor, quinoline as the pi-conjugated bridge, benzothiadiazole (BIM27) and N-propylbenzotriazole (BIM28) as the auxiliary acceptors and cyanoacrylic acid as the anchoring group were synthesized and used as the sensitizers for dye-sensitized solar cells (DSSCs). It was found that BIM 27 exhibits anti-aggregation ability, whereas BIM28 forms the undesired aggregates. Therefore, chenodeoxycholic acid (CDCA) and diethylenetriamine (DETA) molecules were employed as the co-adsorbents to suppress the dye aggregation of BIM28. The DSSC with DETA exhibited a highest power conversion efficiency (PCE) of 3.89%, a remarkable improvement of 25% compared with 3.11% of the cell fabricated without co-adsorbent, exceeding that of the benchmark CDCA-based cell (3.57%) under AM 1.5G conditions. The small DETA can effectively insert between the bulky dye molecules compared to the large CDCA, resulting a more compact dye packing on TiO2, able to less charge recombination. The results demonstrate that DETA may be more efficient for co-adsorption of the bulky dyes.