Photovoltaic performance of solid-state DSSCs sensitized with organic isophorone dyes: Effect of dye-loaded amount and dipole moment

Two isophorone sensitizers (S4 and D-3) were utilized in solid-state dye-sensitized solar cells (DSSCs) using spiro-OMeTAD as hole-transporting material. The dye-loaded amount of D-3 was almost 1.5 times as that of S4 which lead to higher light harvesting efficiency than S4. Moreover, the larger dipole moment along the direction for D-3 could cause more negative charges located close to the TiO2 surface than that of S4, resulting in a larger conduction band (CB) upshift of TiO2 for D-3 which was beneficial to an increase of Voc. Promising results sensitized by D-3 in solid-state DSSCs were achieved with a short-circuit photocurrent density (Jsc) of 3.4 mA cm−2, an open-circuit photovoltage (Voc) of 760 mV, a fill factor (FF) of 0.71, and an overall efficiency (η) of 1.92% while ruthenium dye N3 produced a η of 2.55% under the same conditions (AM 1.5, 100 mW cm−2).

► Two isophorone sensitizers were utilized in solid-state DSSCs.
► The donor indoline unit can exhibit better absorption performance with respect to triphenylamine unit.
► The more favorable dipole moment and adsorption form of D-3 leads to a larger CB upshift in energy level.
► The performances sensitized with D-3 in solid-state DSSCs were achieved with an overall efficiency η of 1.92%.