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Title: Probing the Electronic Structure of a Photoexcited Solar Cell Dye with Transient X-ray Absorption Spectroscopy

This study uses transient X-ray absorption (XA) spectroscopy and timedependent density functional theory (TD-DFT) to directly visualize the charge density around the metal atom and the surrounding ligands following an ultrafast metal-to-ligand charge-transfer (MLCT) process in the widely used RuII solar cell dye, Ru(dcbpy)2(NCS)2 (termed N3). We measure the Ru L-edge XA spectra of the singlet ground (1A1) and the transient triplet (3MLCT) excited state of N34 and perform TD-DFT calculations of 2p core-level excitations, which identify a unique spectral signature of the electron density on the NCS ligands. We find that the Ru 2p, Ru eg, and NCS orbitals are stabilized by 2.0, 1.0, and 0.6 eV, respectively, in the transient 3MLCT state of the dye. These results highlight the role of the NCS ligands in governing the oxidation state of the Ru center.
Authors:
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Publication Date:
OSTI Identifier:
1134239
Report Number(s):
LBNL-6646E
Journal ID: ISSN 1948-7185
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry Letters; Journal Volume: 3; Journal Issue: 12
Publisher:
American Chemical Society
Research Org:
Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
Sponsoring Org:
Advanced Light Source Division; Chemical Sciences Division
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY femtosecond X-ray spectroscopy, transition-metal complex, orano-metallic, dye-sensitized solar cell, charge transfer