Anti-recombination organic dyes containing dendritic triphenylamine moieties for high open-circuit voltage of DSSCs

• Three novel organic dyes with dendritic triphenylamine moieties are synthesized.
• The DSSCs sensitized by three dyes display high open-circuit voltage exceeding 0.8 V.
• A pendent triphenylamine group in the π-bridge of dyes can increase open-circuit voltage of DSSC.

Three novel sensitizers with dendritic triphenylamine moieties were synthesized and used for dye-sensitized solar cells (DSSCs). Their absorption spectra, electrochemical and photovoltaic properties were extensively investigated. All three DSSCs exhibit high open-circuit voltage over 0.8 V. The photovoltaic results indicate that the dendritic triphenylamine units improve the open-circuit voltage, which is attributed to the retardation of charge recombination, demonstrating that non-planar and larger molecules exert better blocking function. Under standard global AM 1.5 solar conditions, the best performance of the DSSCs exhibits a short-circuit current density of 10.35 mA cm−2, an open-circuit voltage of 0.836 V and a fill factor of 0.68, corresponding to an overall conversion efficiency of 5.87%.

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