title: Lithium salts as "redox active" p-type dopants for organic semiconductors and their impact in solid-state dye-sensitized solar cells.
abstract: Lithium salts have been shown to dramatically increase the conductivity in a broad range of polymeric and small molecule organic semiconductors (OSs). Here we demonstrate and identify the mechanism by which Li(+) p-dopes OSs in the presence of oxygen. After we established the lithium doping mechanism, we re-evaluate the role of lithium bis(trifluoromethylsulfonyl)-imide (Li-TFSI) in 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9'-Spirobifluorene (Spiro-OMeTAD) based solid-state dye-sensitized solar cells (ss-DSSCs). The doping mechanism consumes Li(+) during the device operation, which poses a problem, since the lithium salt is required at the dye-sensitized heterojunction to enhance charge generation. This compromise highlights that new additives are required to maximize the performance and the long-term stability of ss-DSSCs.
authors: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, UK.
authors: Antonio
authors: A
authors: Abate
authors: Tomas
authors: T
authors: Leijtens
authors: Sandeep
authors: S
authors: Pathak
authors: Joël
authors: J
authors: Teuscher
authors: Roberto
authors: R
authors: Avolio
authors: Maria E
authors: ME
authors: Errico
authors: James
authors: J
authors: Kirkpatrik
authors: James M
authors: JM
authors: Ball
authors: Pablo
authors: P
authors: Docampo
authors: Ian
authors: I
authors: McPherson
authors: Henry J
authors: HJ
authors: Snaith