A new heteroleptic ruthenium sensitizer enhances the absorptivity of mesoporous titania film for a high efficiency dye-sensitized solar cell

摘要

A heteroleptic polypyridyl ruthenium complex, cis-Ru(4,4'-bis(5-octylthieno[3,2-b]thiophen-2-yl)-2,2'-bipyridine)(4,4'-di-carboxyl-2,2'-bipyridine)(NCS)_2, with a high molar extinction coefficient of 20.5 × 10~3 M~(-1) cm~(-1) at 553 nm has been synthesized and demonstrated as a highly efficient sensitizer for a dye-sensitized solar cell, giving a power conversion efficiency of 10.53% measured under an irradiation of air mass 1.5 global (AM 1.5G) full sunlight. The sensitizer is a pivotal element in the nanocrystalline dye-sensitized solar cell (DSC) which is very promising for future photovoltaic applications due to its high efficiency and low production cost. While an impressive device efficiency has been reached with a metal-free organic dye possessing a very high molar extinction coefficient,2 it is fair to note that the DSC efficiency record of～11.1% measured under the irradiance of AM 1.5G sunlight is held by the well-known N719 or black dye in combination with a thick mesoscopic titania film.