Enhanced exciton diffusion in an organic photovoltaic cell by energy transfer using a phosphorescent sensitizer

Wade A. Luhman, Russell J. Holmes

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Abstract

We demonstrate enhanced exciton diffusion in an organic photovoltaic cell through the incorporation of a phosphorescent sensitizer. The increase in exciton diffusion length (LD) is realized using a composite electron donor layer consisting of a N, N′ -bis(naphthalen-1-yl)- N, N′ -bis(phenyl)-benzidine (NPD) host doped with the phosphorescent guest fac -tris(2-phenylpyridine) iridium [Ir (ppy) 3]. The presence of the phosphor at low concentration allows for the population of the long-lived NPD triplet state and an increase in LD. An increase in the NPD LD from 6.5±0.3 to 11.8±0.6 nm is extracted from measurements of the external quantum efficiency for donor layers containing 5 wt % Ir (ppy) 3. This enhancement leads to a ∼80% improvement in the power conversion efficiency relative to devices containing an undoped donor layer.

Original languageEnglish (US)
Article number153304
JournalApplied Physics Letters
Volume94
Issue number15
DOIs
StatePublished - 2009

Bibliographical note

Funding Information:
This work was supported in part by the NSF MRSEC Program under Award Nos. DMR-0212302 and DMR-0819885.

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