The improved photocurrent density of D35-cpdt and DN-F10 via co-sensitization process in dye-sensitized solar cells

The mixture of two organic dyes, D35-cpdt and DN-F10, namely, LEG4 and DB, were used as the efficient co-sensitizers with cobalt(II/III) redox mediator in dye-sensitized solar cells (DSSCs). The co-sensitized system is optimized via the variation of DB amount while maintaining a constant amount of LEG4 dye. We achieve an improved photovoltaic performance as the utilization of the co-sensitized dye systems in DSSC devices. The individual dye LEG4 and DB can produce the efficiency of 3.10% and 3.50%, respectively, while the efficiency up to 5.60% can be achieved in co-sensitized dye system (LEG:DB). The photocurrent ( J SC = 8.40 mA cm −2 ), open-circuit voltage ( V OC = 0.73 V), and fill factor (FF = 0.50) are also enhanced under AM 1.5 G illumination with the 100 mW·cm −2 intensity. High steady state in the dye mixture can be attributed to the increased photocurrent and power conversion efficiency. The co-sensitization system of two dyes can reduce the recombination loss. The study shows that the co-sensitizing dye system has complementary characteristics and provides a broader optical absorption, which can harvest photons in a wider spectral region to increase photocurrent density in the devices with the co-sensitized dye system as well as better charge transport. This current work will be significant for the performance enhancement of photovoltaic conversion via the mixture of dyes. Graphical abstract The two organic dyes LEG4 (red) and DB (blue) have complementary spectra and are used as the co-sensitized dye in dye-sensitized solar cells. The performance of photoelectricity conversion can be significantly improved.