Multifunctional conjugated molecules combined with electrospun CuCoP/carbon nanofibers as a modifier of the Pt counter electrode for dye-sensitized solar cells

Star-shaped 3,6-bis(5-(4,4 '-bis(3-azidopropyl)-[1,1 ':3 ',1 '-terphenyl]-5 '-yl)-thien-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DPPTPTA) is combined with electrospun bimetallic copper-cobalt phosphide decorated on carbon nanofibers (CuCoP/CNF) and used as a modified layer (DPPTPTA@CuCoP/CNF) on the platinum (Pt) coated counter electrode (CE) of dye-sensitized solar cells (DSSCs). DPPTPTA possesses ladder-like energy levels for efficient charge separation while CuCoP/CNF exhibits high electrocatalytic activity and sufficient electrical conductivity. Overall, the DPPTPTA@CuCoP/CNF heterostructure exhibits attractive performance needed for CE of DSSCs. From electrochemical analysis, it is observed that the DPPTPTA@CuCoP/CNF modified layer ensures efficient charge transfer at the CE/electrolyte interface with low charge transfer resistance. Moreover, the CE/electrolyte interface possesses a small electron recombination rate, since the modified layer has good charge separation ability. Under 1 sun (AM 1.5G, 100 mW cm(-2)) conditions, the proposed DSSC achieved a photoelectric conversion efficiency (eta) of 9.50%, an open-circuit voltage (V-OC) of 827 mV, a short-circuit current density (J(SC)) of 16.25 mA cm(-2), and a fill factor (FF) of 0.71. Under indoor conditions, the eta value at 6000 lux (1.89 mW cm(-2)) reached 25.44%. Finally, the porous three-dimensional nanofiber structure of modified layer can ensure the long-term stability (90% retention after 3000 h). Thus, the DPPTPTA@CuCoP/CNF modified layer-based DSSC can be considered as a promising device for possible renewable energy applications.

Automated summary

By combining DPPTPTA and CuCoP/CNF, a modified layer DPPTPTA@CuCoP/CNF was prepared and applied to the CE of DSSCs. The modified layer exhibits good charge separation ability and catalytic activity, leading to excellent performance in terms of photoelectric conversion efficiency and stability.