Tio2 paste

Firstly, the FTO glass sheet (2 × 1.5 cm²) was cleaned using a bath sonication process in soap water, acetone and distilled water for 10 min in every case. Thin-film deposition (0.20 cm² area) of the TiO₂ paste (Solaronix) on the FTO glass was performed by the doctor blade technique, followed by heating at 75 °C for 30 min to remove the low boiling point organic solvent. It was annealed at 450 °C for 30 min, resulting in a transparent thin film of TiO₂ on FTO glass. The QD deposition was performed following our previously reported method. Briefly, the as-prepared CdS QDs were dispersed in isopropanol by ultrasonication for 15 min and CdS QDs were deposited on the TiO₂ film using a spin coater (Spin NXG-P1) at 1500 rpm for 15 min to form a uniform TiO₂/CdS film. Similarly, CdSe QDs were dispersed in hexane and were deposited on the TiO₂/CdS film, similarly. During the preparation of photoanode, the deposition of each layer of QDs was dried at 75 °C for 30 min to remove the solvent for better film formation. The prepared photoanode was kept in a vacuum under dark conditions at room temperature. It was used in the fabrication of QDSSC devices.

Cadmium nitrate (Sigma-Aldrich), sodium sulphide (Himedia), TiO₂ paste (Solaronix), graphite flake (Sigma-Aldrich), sodium hydride (NaH), poly(tetramethylene glycol) (PTMG, M_n = 2900 g mol⁻¹), butane-di-ol (Sigma-Aldrich), 4,4′-diphenylmethane diisocyanate (MDI, Sigma-Aldrich), titanium tetrachloride (TiCl₄, Strem), N,N-dimethylacetamide (DMA), dibutyl tin dilaurate (DBTDL), propane sultone (Sigma-Aldrich), and ethanol were used for the synthesis process.