Full Paper
Energy Upconversion via Triplet Fusion in Super Yellow PPV Films Doped with Palladium Tetraphenyltetrabenzoporphyrin: a Comprehensive Investigation of Exciton Dynamics
Article first published online: 27 AUG 2012
DOI: 10.1002/adfm.201201284
Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Additional Information
How to Cite
Jankus, V., Snedden, E. W., Bright, D. W., Whittle, V. L., Williams, J. A. G. and Monkman, A. (2013), Energy Upconversion via Triplet Fusion in Super Yellow PPV Films Doped with Palladium Tetraphenyltetrabenzoporphyrin: a Comprehensive Investigation of Exciton Dynamics. Adv. Funct. Mater., 23: 384–393. doi: 10.1002/adfm.201201284
Publication History
- Issue published online: 11 JAN 2013
- Article first published online: 27 AUG 2012
- Manuscript Revised: 6 AUG 2012
- Manuscript Received: 11 MAY 2012
Keywords:
- organic solar cells;
- triplet annihilation;
- triplet fusion;
- super yellow;
- energy upconversion
Abstract
One of the key issues concerning the development of efficient polymer solar cell technology is the lack of viable materials which absorb in the near-infrared (NIR) region. This could be resolved by up-converting energy from the NIR into visible using triplet fusion (TF) with an additional layer that is fabricated separately from the solar cell and deposited on top. Theoretically a maximum upconversion (UC) via TF efficiency of 50% could be obtained. Here, it is demonstrated that in a film of commercially available poly(para-phenylene vinylene) copolymer “super yellow” (SY) doped with 4% palladium(meso-tetraphenyl-tetrabenzoporphyrin) (PdTPBP) sensitizer, an UC efficiency of 6% can be achieved. By using femtosecond and nanosecond spectroscopies it is shown that the main UC efficiency loss mechanism is due to triplet quenching in PdTPBP aggregates. The PdTPBP intersystem crossing rate constant is determined to be 1.8 × 1011 s−1 and the triplet energy transfer rate constant from PdTPBP to SY to be 109 s−1. Quenching in PdTPBP aggregates can account for a triplet concentration loss in the range of 76-99%. As such, preventing sensitizer aggregation in NIR-to-visible upconverting films is crucial and may lead to substantial increase of UC efficiencies in films.

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