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Excited‐State Dynamics of [Ru(bpy) 3 ] 2+ Thin Films on Sensitized TiO 2 and ZrO 2
Author(s) -
Leandri Valentina,
Liu Peng,
Sadollahkhani Azar,
Safdari Majid,
Kloo Lars,
Gardner James M.
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201801010
Subject(s) - excited state , thin film , materials science , analytical chemistry (journal) , chemistry , atomic physics , nanotechnology , physics , chromatography
The excited state dynamics of Tris(2,2′‐bipyridine)ruthenium(II) hexafluorophosphate, [Ru(bpy) 3 (PF 6 ) 2 ], was investigated on the surface of bare and sensitized TiO 2 and ZrO 2 films. The organic dyes LEG4 and MKA253 were selected as sensitizers. A Stern–Volmer plot of LEG4‐sensitized TiO 2 substrates with a spin‐coated [Ru(bpy) 3 (PF 6 ) 2 ] layer on top shows considerable quenching of the emission of the latter. Interestingly, time‐resolved emission spectroscopy reveals the presence of a fast‐decay time component (25±5 ns), which is absent when the anatase TiO 2 semiconductor is replaced by ZrO 2 . It should be specified that the positive redox potential of the ruthenium complex prevents electron transfer from the [Ru(bpy) 3 (PF 6 ) 2 ] ground state into the oxidized sensitizer. Therefore, we speculate that the fast‐decay time component observed stems from excited‐state electron transfer from [Ru(bpy) 3 (PF 6 ) 2 ] to the oxidized sensitizer. Solid‐state dye sensitized solar cells (ssDSSCs) employing MKA253 and LEG4 dyes, with [Ru(bpy) 3 (PF 6 ) 2 ] as a hole‐transporting material (HTM), exhibit 1.2 % and 1.1 % power conversion efficiency, respectively. This result illustrates the possibility of the hypothesized excited‐state electron transfer.