In situ grown NiIn 2 S 4 nanosheets as counter electrode for bifacial quasi-solid-state dye-sensitized solar cells

The development of counter electrode (CE) catalytic materials with cost-effective and excellent catalytic activity, transparency, good stability, and simple fabrication process is urgently needed for bifacial quasi-solid-state dye-sensitized solar cells (BQDSSCs). Herein, NiS 1.97 nanoparticles, In 2.77 S 4 and NiIn 2 S 4 nanosheet structures were successfully constructed by a one-step in situ solvothermal method on an FTO glass substrate to act as counter electrodes (CEs). The electrochemical results revealed that the NiIn 2 S 4 interconnected nanosheet CE exhibited enhanced electrocatalytic activity for the reduction of I 3 − , which can be attributed to the unique structure with a large contact area for the electrolyte and FTO substrate, enhancing electron transfer and providing effective catalytic sites. The BQDSSCs based on the NiIn 2 S 4 CE showed the superior front and rear illumination J sc values of 15.27 and 9.13 mA cm −2 , and power conversion efficiencies (PCEs) of 8.00% and 4.59%, respectively, which were higher than those of binary NiS 1.97 and In 2.77 S 4 , and comparable to the Pt CE with front and rear efficiencies of 7.42% and 3.93%, respectively. Furthermore, the NiIn 2 S 4 CE film displayed a high multiple on–off switching response and good stability, suggesting that ternary sulfides could be promising alternatives for CE materials in BQDSSCs. Graphic abstract The NiIn 2 S 4 nanosheet BQDSSC yields front and rear PCEs of 8.00 and 4.59%, higher than those of NiS 1.97 , In 2.77 S 4 , and Pt CEs, respectively.