Enhancing DSSCs and Photocatalytic Hydrogen Production with D‐A1‐A2‐π‐A Sensitizers Containing 10′H‐Spiro [Fluorene‐9,9′‐Phenanthren]‐10′‐one and Benzo[c][1,2,5]Thiadiazole

Abstract

AbstractNovel D‐A1‐A2‐π‐A organic sensitizers (FZ‐sensitizer), utilizing spiro [fluorene‐9,9′‐phenanthren]‐10′‐one and benzo [c][1,2,5]thiadiazole moiety as two auxiliary acceptors, are synthesized and applied in dye‐sensitized solar cells (DSSCs) and hydrogen production. By incorporating a bulky spiro [fluorene‐9,9′‐phenanthrene]‐10′‐one (A1) and benzo[c][1,2,5]thiadiazole (A2) between the donor (D) and π‐bridge moiety, structural modifications inhibit molecular aggregation, while the carbonyl group enhances the capture of Li+ ions, thereby delaying charge recombination. Furthermore, the extended π‐conjugation broadens the light absorption range and enhances the power conversion efficiency (PCE) of FZ‐2 under AM1.5 conditions, achieving up to 5.72%. Co‐sensitization with N719 and FZ‐2 shows PCE of 9.60% under one sun. Under TL84 indoor light conditions, the efficiency is 29.69% at 2500 lux. The superior co‐sensitization performance of N719 and FZ‐2 can be attributed to FZ‐2′s high absorptivity at short wavelengths, compensating for N719′s shortcomings in this range. FZ‐sensitizers also exhibit high efficiency in photocatalytic hydrogen production. The hydrogen production activities of FZ‐2 are 9190 μmol/g (1 hour) and 76582 μmol/g (12 hours) respectively, while those of FZ‐1 are 7430 μmol/g (1 hour) and 64004 μmol/g (12 hours), indicating that FZ‐2 can inject charges into TiO2 more efficiently and utilize them for water splitting. Stability testing of photocatalytic water splitting after 12 hours shows a turnover number (TON) of 4249 for FZ‐1 and 5378 for FZ‐2.