Synthesis and photovoltaic performance of asymmetric di-anchoring organic dyes

• Two novel asymmetric di-anchoring dyes were synthesized for DSSCs.
• The dyes can increase the molar extinction coefficients significantly.
• The dyes display broad spectra responses.
• The dyes effectively improve the short-circuit photocurrent density.

Two novel metal-free organic dyes bearing two asymmetric double donor–acceptor segments were synthesized. Their physical, optical, electrochemical properties and photovoltaic performances were investigated. Compared with the mono-anchoring dye containing single donor–acceptor chain, these new dyes exhibited a broader and much stronger absorption in the light wavelength ranging from 400 to 600 nm, showed higher IPCE values and short-circuit current density, which led to more efficient photovoltaic performance. The dye with triphenylamine and phenothiazine as two electron donors and two cyanoacrylic acids as two electron acceptors exhibited an impressive power conversion efficiency of 5.92% under simulated AM 1.5 G illumination condition with an open-circuit photovoltage of 796 mV, a short-circuit photocurrent density of 11.24 mA/cm2, which is 22% higher than that of the mono-anchoring dye based counterpart. The results indicate that the asymmetric di-anchoring organic dyes are promising sensitizers for high efficient dye-sensitized solar cells.

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