Optimization of dye-sensitized solar cells prepared by compression method

Nanostructured TiO2 films have been deposited onto conducting glass and on flexible conducting plastic substrates using a compression technique. Dye-sensitized solar cells prepd. from Degussa P25 TiO2 powder, red dye (Ru(dcbpy)2(SCN)2)(NBu4)2 (dcbpy = 2,2'-bipyridine-4,4'-dicarboxylate) or black dye (Ru(tcterpy)(SCN)3) (tcterpy = 4,4',4''-tricarboxy-2,2':6',2''-terpyridine) and an electrolyte contg. LiI and I2 in 3-methoxypropionitrile were tested using std. photoelectrochem. techniques. The av. overall efficiency of small open cells sensitized with the red dye on plastic substrates was 4.5% (100 W-m-2). In a direct comparison, red and black dye gave about the same efficiencies. For both dyes, addn. of 4-tert-butylpyridine to the electrolyte resulted in a decreased IPCE response in the whole spectral range, with a specific decrease in the red region, which is attributed to a shift in the conduction band edge of the nanostructured TiO2.