Enhanced photovoltaic performances of dye-sensitized solar cell using self-charring phosphate ester surfactant

[Display omitted] ► The phosphate-terminated Triton™ X provides char (∼9 wt.%) at 600 °C under air. ► The dispersant leads to finer and more close-packed TiO 2 film after firing. ► The DSSC employing the TiO 2 film shows improved Jsc and Voc under 1 sun illumination. In this article, we describe the use of Triton™ X-based surfactants with an octyl phenol ethoxylate (OPE) backbone and a phosphate ester chain end as a dispersant for formulating TiO 2 paste. Three phosphate-terminated Triton™ X (or OPE) derivatives, i.e. [OPE2-OPO(OH) 2], [OPE5-OPO(OH) 2], and [OPE10-OPO(OH) 2] are prepared from OPEs of different oxyethylene units and phosphorous pentoxide. The phosphate-terminated Triton™ X of the highest number of oxyethylene units ( i.e. OPE10-OPO(OH) 2) provides the desirable amount of char (9 wt.%) at 600 °C under air atmosphere, and is found to lower the viscosity of [TiO 2/ethyl cellulose/terpineol] paste, leading to finer and more close-packed TiO 2 film after firing. The photoanode film prepared by the TiO 2 paste was built up on a conducting glass plate by a screen printing process followed by a heat treatment for sintering. Then, the TiO 2 film showed not only higher particle density, but also residual char on the particle surface in comparison with the control sample film prepared from the [TiO 2/ethyl cellulose/terpineol] paste with no dispersant. The dye-sensitized solar cell (DSSC) employing the prepared nanocrystalline TiO 2 film with char exhibits significantly improved photovoltage and photocurrent characteristics under 1 sun illumination.