Synthesis of bianchored metal free organic dyes for dye sensitized solar cells

Two bianchored metal free organic dyes (Car-th-CN and Dpa-th-CN) were designed and synthesized for DSSC application, in which carbazole or diphenylamine moieties were used as the donor, cyano vinyl thiophene unit as the π-bridge and cyanoacrylic acid group as the electron acceptor. The structures of the synthesized dyes were confirmed by NMR, HR-Mass and elemental analysis. The optical, electrochemical, theoretical and photovoltaic properties of the synthesized dyes were investigated. Fabricated photovoltaic devices based on carbazole unit as a donor (Car-th-CN) showed a maximum current conversion efficiency of 4.04% under AM 1.5 illumination (85 mW cm−2) and monochromatic incident photon to current efficiency (IPCE) of 38.1%. The reason for the higher efficiency of Car-th-CN is due to the planar nature of carbazole moiety and hence increases the capability of adsorbed dye amount and electron lifetime in TiO2 surface.

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► Synthesis of diphenylamine and carbazole donor based metal free organic dyes.
► The electrochemical, photophysical and theoretical properties were established for the synthesized dyes.
► Fabricated photovoltaic device based on carbazole as donor shows good efficiency.