A Hydroxamic Acid Anchoring Group for Durable Dye‐Sensitized Solar Cells Incorporating a Cobalt Redox Shuttle

A hydroxamic acid group has been employed for the first time as an anchoring group for cobalt‐based dye‐sensitized solar cells (DSSCs). The porphyrin dye YD2‐ o ‐C8HA including a hydroxamic acid anchoring group exhibited a power conversion efficiency ( η ) of 6.4 %, which is close to that of YD2‐ o ‐C8 , a representative porphyrin dye incorporating a conventional carboxylic acid. More importantly, YD2‐ o ‐C8HA was found to be superior to YD2‐ o ‐C8 in terms of both binding ability to TiO 2 and durability of cobalt‐based DSSCs. Notably, YD2‐ o ‐C8HA photocells revealed a higher η ‐value (4.1 %) than YD2‐ o ‐C8 (2.8 %) after 500 h illumination. These results suggest that the hydroxamic acid can be used for DSSCs with other transition‐metal‐based redox shuttle to ensure high cell durability as well as excellent photovoltaic performance.