A Molecularly Tailored Photosensitizer with an Efficiency of 13.2% for Dye‐Sensitized Solar Cells

Abstract Photosensitizers yielding superior photocurrents are crucial for copper‐electrolyte‐based highly efficient dye‐sensitized solar cells (DSCs). Herein, two molecularly tailored organic sensitizers are presented, coded ZS4 and ZS5, through judiciously employing dithieno[3,2‐b:2″,3″‐d]pyrrole (DTP) as the π‐linker and hexyloxy‐substituted diphenylquinoxaline (HPQ) or naphthalene‐fused‐quinoxaline (NFQ) as the auxiliary electron‐accepting unit, respectively. Endowed with the HPQ acceptor, ZS4 shows more efficient electron injection and charge collection based on substantially reduced interfacial charge recombination as compared to ZS5. As a result, ZS4‐based DSCs achieve a power conversion efficiency (PCE) of 13.2% under standard AM1.5G sunlight, with a high short‐circuit photocurrent density (J_sc) of 16.3 mA cm⁻², an open‐circuit voltage (V_oc) of 1.05 V and a fill factor (FF) of 77.1%. Remarkably, DSCs sensitized with ZS4 exhibit an outstanding stability, retaining 95% of their initial PCE under continuous light soaking for 1000 h. It is believed that this is a new record efficiency reported so far for copper‐electrolyte‐based DSCs using a single sensitizer. The work highlights the importance of developing molecularly tailored photosensitizers for highly efficient DSCs with copper electrolyte.