Connecting Direct C−H Arylation Reactions with Dye‐Sensitized Solar Cells: A Shortcut to D–A–π–A Organic Dyes

A step‐economical synthetic strategy is developed to target thieno[3,4‐ c ]pyrrole‐4,6‐dione (TPD)‐based D–A–π–A organic dyes for dye‐sensitized solar cells (DSSCs). Through sequential Pd‐catalyzed direct C−H (hetero)arylation reaction, synthesis of the push–pull‐type small molecules is reduced from the traditional six steps to two steps. In this report, we focus on the optimization of the key C−H monoarylation of TPD by screening ligands, acid additives, bases, and solvents. The reaction proves versatile toward new D–A–π–A organic dyes with a variety of different donor groups, and several derivatives are efficiently prepared under optimum reaction conditions. The sensitive aldehyde functionality that is a required intermediate for conversion into anchoring groups for TiO 2 is well tolerated. Based on our synthetic study, DSSCs are fabricated and characterized using two designed sensitizers. The photovoltaic characterization of the devices affords an open‐circuit voltage of 0.60–0.69 V, a short‐circuit current density of 10.85–11.07 mA cm −2 , and a fill factor of 69.9–70.8 %, which corresponds to an overall power conversion efficiency of 4.61–5.33 %.