Extraction of Schottky barrier at the F-doped SnO2/TiO2 interface in Dye Sensitized solar cells

The Schottky barrier between the nanoporous TiO2/F–doped SnO2 interface is extracted via experiment for the first time using two independent approaches. In the first approach, Ohmic contacts using Ti and Al on nanoporous TiO2 film are made to facilitate temperature dependant IV measurements. An extracted barrier height of ∼0.6 eV at the TiO2/F–doped SnO2 assuming a theoretical value of the Richardson's constant is obtained. The barrier height is incorrectly deduced to be 0.31 eV if a Richardson constant extracted from experimental data fitted to thermionic emission theory is employed. In the second approach, a voltage dependent barrier height of 0.53 eV at T = 285 K is extracted from the dark current characteristics of a dye sensitized solar cell contacted to the nanoporous TiO2 film via the dye, electrolyte as normal. The analysis shows that in dye sensitized solar cell, the impact of such a barrier is dominant only beyond open circuit voltage conditions in the range above 1–1.2 V.