Efficient Solar Cells Based on Porphyrin and Concerted Companion Dyes Featuring Benzo 12-Crown-4 for Suppressing Charge Recombination and Enhancing Dye Loading.

In recent years, various porphyrin dyes have been designed to develop efficient dye-sensitized solar cells (DSSCs). Based on our previously reported porphyrin dye , which contains a phenothiazine donor with two diethylene glycol (DEG)-derived substituents, we herein report a porphyrin dye by introducing a benzo 12-crown-4 (BCE) unit onto the N atom of the phenothiazine donor. On this basis, and have been synthesized by replacing a DEG chain in with two DEG chains and a 12-crown-4 unit, respectively. For iodine electrolyte-based DSSCs, dyes exhibit values of 765-779 mV, higher than that of (755 mV), which may be related to the strong capability of the BCE group in binding Li and thus suppressing the downward shift of the TiO conduction band and interfacial charge recombination. Moreover, the smaller size of 12-crown-4 than the DEG unit enables higher adsorption amounts of the dyes than , contributing to an enhanced value. Due to the presence of two BCE units, dye exhibits the highest dye loading amount and of 1.86 × 10 mol cm and 19.79 mA cm, respectively, affording a high PCE of 11.1%. To further enhance the light-harvesting ability, a concerted companion (CC) dye has been constructed by linking the two subdye units corresponding to the porphyrin dye and an organic dye. As a result, affords an enhanced and efficiency. Further coadsorption of with chenodeoxycholic acid achieved the highest efficiency of 12.1%. This work provides an effective approach for fabricating efficient DSSCs sensitized by porphyrin and CC dyes based on the introduction of crown ether units with smaller sizes and stronger Li affinities.