Low glass transition temperature hole transport material in enhanced-performance solid-state dye-sensitized solar cell

A new triarylamine-based hole transport materials (HTM) with branched side chain giving low glass transition temperature (T-g) is synthesized and incorporated into a solid state dye sensitized solar cell. This designing of molecular structure of HTM for lowering the T-g along with viscosity and surface tension of the casting solution effectively increases the pore-filling fraction (PFF) as the cell is heated during the fabrication, leading to an 8 fold increasing in cell efficiency over cells without heat treatment. We relate the cell performance improvement not only due to the PFF of TiO2 by the (HTM), but also because of morphological and thickness changes in the hole transport material (HTM) capping layer. (C) 2014 Elsevier B.V. All rights reserved.