11% efficiency solid-state dye-sensitized solar cells with copper(II/I) hole transport materials.

Cao, Yiming; Saygili, Yasemin; Ummadisingu, Amita; Teuscher, Joël; Luo, Jingshan; Pellet, Norman; Giordano, Fabrizio; Zakeeruddin, Shaik Mohammed et al. · Nat Commun · 2017

basic_science · Level V

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Abstract

Solid-state dye-sensitized solar cells currently suffer from issues such as inadequate nanopore filling, low conductivity and crystallization of hole-transport materials infiltrated in the mesoscopic TiO<sub>2</sub> scaffolds, leading to low performances. Here we report a record 11% stable solid-state dye-sensitized solar cell under standard air mass 1.5 global using a hole-transport material composed of a blend of [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)<sub>2</sub>](bis(trifluoromethylsulfonyl)imide)<sub>2</sub> and [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)<sub>2</sub>](bis(trifluoromethylsulfonyl)imide). The amorphous Cu(II/I) conductors that conduct holes by rapid hopping infiltrated in a 6.5 μm-thick mesoscopic TiO<sub>2</sub> scaffold are crucial for achieving such high efficiency. Using time-resolved laser photolysis, we determine the time constants for electron injection from the photoexcited sensitizers Y123 into the TiO<sub>2</sub> and regeneration of the Y123 by Cu(I) to be 25 ps and 3.2 μs, respectively. Our work will foster the development of low-cost solid-state photovoltaic based on transition metal complexes as hole conductors.