Improved performance of Black-dye-sensitized solar cells with nanocrystalline anatase TiO2 photoelectrodes prepared from TiCl4 and ammonium carbonate

To improve the performance of tris(isothiocyanato)-ruthenium(II)-2,2′:6′,2′′-terpyridine-4,4′,4″-tricarboxylic acid, tris-tetrabutylammonium salt (Black-dye) sensitized TiO2 solar cells, nanocrystalline TiO2 particles, which were used as film photoelectrodes, were synthesized from TiCl4 and ammonium carbonate. The resulting nanocrystalline TiO2 particles, which had a pure anatase crystal structure, had smaller surfaces areas, larger size distribution and mean size compared to nanoparticles prepared by the traditional method using titanium(IV) tetraisopropoxide (Ti(OCH(CH3)2)4) and HNO3. The dye-adsorbed TiO2 photoelectrode synthesized from TiCl4 and ammonium carbonate had a more thorough surface coverage of the Black-dye. The short circuit photocurrent density (Jsc) and the incident monochromatic photon-to-electron conversion efficiency (IPCE) value of the cell using TiO2 prepared from TiCl4 were higher than that prepared from Ti(OCH(CH3)2)4. Consequently, the solar energy conversion efficiency (η) is 16% larger under AM 1.5 (1sun, 100 mW/cm2). The characterizations of the TiO2 photoelectrode suggested that pure anatase crystallites, the less surface area and the more thorough surface coverage of the sensitizing dye enhance the absorbed photon to current efficiency (APCE) and the light harvesting efficiency (LHE), respectively, which improves the IPCE, Jsc, and the η values.