Electron transport properties in dye-sensitized solar cells with {001} facet-dominant TiO₂ nanoparticles

Dye-sensitized solar cells (DSSCs) with reactive {001} facet-dominant TiO₂ have attracted a great deal of attention owing to their high solar cell performance, despite the origin and the variation of the results being controversial. Here, we report the characteristic charge transport properties of DSSCs composed of {001} and {101} facet-dominant TiO₂ nanoparticles in order to explain the origin of solar cell performance. Based on transient photocurrent and photovoltage measurements and transient absorption spectroscopy, the energetics of TiO₂ semiconductors and dye sensitizers are utilized to understand the electron diffusion, recombination, and injection kinetics to determine solar cell performance. Novel strategies to improve DSSC performance by utilizing the characteristics of {001} facet-dominant TiO₂ nanoparticles are proposed, which are (1) enhancement of electron injection and (2) reduction of carrier recombination for J_SC and V_OC improvement, despite the drawback of slower electron diffusion in the mesoporous network of {001} facet-dominant TiO₂.