Chiang Mai Journal of Science

We have prepared diamondoid (adamantane) coated on a silicon substrate via a chemical vapor deposition (CVD) technique (ADA/Si: CVD) electrode. This electrode was used as a counter electrode of dye-sensitized solar cells (DSSCs) and this led to high short circuit current density (Jsc). The high Jsc can be explained by the resistive switching behavior of diamondoids films where the resistivity on the forward bias is lower than the reverse bias; this makes the transportation of electron at the interface between electrode and electrolyte become easier. By using ultraviolet/X-ray photoemission spectroscopy (UPS/XPS), it was found that ADA/Si: CVD film component of 81% SP2 and 19% of SP3 hybridization of carbon investigated film can conduct and still have the interesting properties of the diamond, such as negative electron affinity (NEA). The Jsc of the ADA/Si: CVD counter electrode is high as 22.1 mA·cm−2 compared to 19.8 mA·cm−2 of Pt reference counter electrode. However, the efficiency of the ADA/Si: CVD counter electrode is lower than the Pt reference counter electrode because the films are low conductive and resulting in the fill factor (FF) of only 0.36. It indicates that we can improve this electrode by optimizing the CVD process conditions. These findings should provide an attractive route to improve DSSC efficiency with lower production costs as well as for catalytic applications spanning perovskite solar cells, supercapacitors, and photocatalytic cells.