Blocking Layers Deposited on TCO Substrate and Their Effects on Photovoltaic Properties in Dye-Sensitized Solar Cells

In this review, we have investigated the effect of TiO 2 -based blocking layers (t-BLs), deposited ona transparent conductive oxide (TCO)-coated glass substrate, on the photovoltaic performance ofdye-sensitized solar cells (DSSCs). The t-BL was deposited using spin-coating or sputteringtechnique, and its thicknesses were varied to study the influence of the thin TiO 2 layer in betweentransparent conducting glass and nanocrystalline TiO 2 (nc-TiO 2 ). The DSSC with the t-BL showedthe improved adhesion and the suppressed charge recombination at a TCO glass substrate thanthose without the t-BL, which led to the higher conversion efficiency. Keywords: Dye-sensitized solar cell, Blocking layers, Transparent conducting oxides, Chargerecombination, Adhesion properties Received May 27, 2011 : Accepted June 3, 2011 1. Introduction Dye-sensitized solar cells have been extensivelystudied since their discovery in 1991 by Gratzel’s researchgroup 1) because they have been considered as a goodalternative to conventional silicon photovoltaic cells dueto their low production costs and colorful characteristics.As a consequence of this special attention, DSSCs withenergy conversion efficiencies higher than 11% have beenobtained using nc-TiO