SYNTHESIS OF RUTHENIUM DYE (N3 DYE) FROM RECYCLED RUTHENIUM TRICHLORIDE FOR APPLICATION IN DYE SENSITIZED SOLAR CELLS

摘要

A solar cell converts electromagnetic energy into electricity and is based on semiconductor physics. The high cost of solar cells, caused by expensive solid-state semi-conductor material, has led to the development of alternative solar cells called dye sensitized solar cells. The dye sensitized solar cells are low cost solar cells which yield electric conversion efficiencies of 11.4percent. These efficiencies are achieved under air mass 1.5 solar irradiation using a ruthenium dye called cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) also known as N3 dye. Cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) complex is used in the dye sensitized solar cell to harvest the sunlight for conversion into electricity. The dye is synthesised in five steps: the recovery of ruthenium as RuCl_(3) from ruthenium waste material; synthesis of the 4,4'-dimethyl-2,2'-bipyridine by coupling two 4-methylpyridine molecules; oxidation of the methyl groups in 4,4'-dimethyl-2,2'-bipyridine by K_(2)Cr_(2)O_(7) in 98percent H_(2)SO_(4) to give 2,2'-bipyridyl-4,4'-dicarboxylic acid; synthesis of the cis-dichlorobis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) complex from RuCl_(3) and 2,2'-bipyridyl-4,4'-dicarboxylic acid and finally the synthesis of cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) (N3 dye) from cis-dichlorobis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II). The percentage yield of the final product, cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II), was 14percent. The FTIR and ~(13)C NMR results indicated the formation of N3 dye with the NCS peak appearing at 2124 cm~(-1) and 139 ppm, respectively.