Four-Photon Molecular Upconversion.
6 affiliations
- 1Department of Mechanical & Aerospace, Engineering, Princeton University, Princeton, New Jersey08544, United States.
- 2Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan48109, United States.
- 3Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey08544, United States.
- 4Department of Chemistry, University of Kentucky, Lexington, Kentucky40506, United States.
- 5Department of Chemistry, North Carolina State University, Raleigh, North Carolina27695, United States.
- 6Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey08544, United States.
Abstract
Triplet-triplet annihilation (TTA) upconversion converts low-energy photons into higher-energy emission, but conventional TTA is limited by its two-photon nature, as the emitted photon energy cannot exceed twice the excitation photon energy. Here, a fully organic solid-state thin-film architecture cascades two TTA upconversion stages through an intermediate Förster resonance energy transfer (FRET) bridge to achieve molecular four-photon upconversion. The first sensitizer/annihilator bilayer upconverts near-infrared (NIR) excitation into intermediate singlets, which are transferred through the FRET bridge to the sensitizer of the second TTA stage. The second sensitizer/annihilator bilayer performs a second TTA step to generate blue emission. The device converts 904 nm excitation into 445 nm emission, corresponding to a 1.41 eV anti-Stokes shift and an emitted photon energy 2.03 times the excitation photon energy, exceeding the maximum possible energy gain with conventional two-photon TTA. Because two quadratic TTA stages are coupled in series, the ideal low-intensity response of the four-photon device is quartic when both stages operate below threshold, providing a steeper nonlinearity desirable for nonlinear sensing. Experimentally, power-dependent measurements reveal a superquadratic slope of 3.03, followed by quadratic and linear regimes as the constituent TTA stages cross their thresholds. Independent stage measurements and time-resolved photoluminescence dynamics support the four-photon mechanism.
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BibTeX
@article{lowe2026fourphoton,
title = {{Four-Photon Molecular Upconversion.}},
author = {Seamus S Lowe and Maxwell Sun and Jesse A Wisch and Kostubh Gaur and Chiao-Jung Su and Azka Arshad and Felix N Castellano and John E Anthony and Noel C Giebink and Barry P Rand},
journal = {Journal of the American Chemical Society},
year = {2026},
month = oct,
doi = {10.1021/jacs.6c17238},
url = {https://europepmc.org/article/MED/42913600},
note = {CC BY},
}
RIS
TY - JOUR
TI - Four-Photon Molecular Upconversion.
AU - Seamus S Lowe
AU - Maxwell Sun
AU - Jesse A Wisch
AU - Kostubh Gaur
AU - Chiao-Jung Su
AU - Azka Arshad
AU - Felix N Castellano
AU - John E Anthony
AU - Noel C Giebink
AU - Barry P Rand
PY - 2026
DA - 2026/10/01
JO - Journal of the American Chemical Society
DO - 10.1021/jacs.6c17238
UR - https://europepmc.org/article/MED/42913600
AB - Triplet-triplet annihilation (TTA) upconversion converts low-energy photons into higher-energy emission, but conventional TTA is limited by its two-photon nature, as the emitted photon energy cannot exceed twice the excitation photon energy. Here, a fully organic solid-state thin-film architecture cascades two TTA upconversion stages through an intermediate Förster resonance energy transfer (FRET) bridge to achieve molecular four-photon upconversion. The first sensitizer/annihilator bilayer upconverts near-infrared (NIR) excitation into intermediate singlets, which are transferred through the FRET bridge to the sensitizer of the second TTA stage. The second sensitizer/annihilator bilayer performs a second TTA step to generate blue emission. The device converts 904 nm excitation into 445 nm emission, corresponding to a 1.41 eV anti-Stokes shift and an emitted photon energy 2.03 times the excitation photon energy, exceeding the maximum possible energy gain with conventional two-photon TTA. Because two quadratic TTA stages are coupled in series, the ideal low-intensity response of the four-photon device is quartic when both stages operate below threshold, providing a steeper nonlinearity desirable for nonlinear sensing. Experimentally, power-dependent measurements reveal a superquadratic slope of 3.03, followed by quadratic and linear regimes as the constituent TTA stages cross their thresholds. Independent stage measurements and time-resolved photoluminescence dynamics support the four-photon mechanism.
SN - 0002-7863
SN - 1520-5126
ER -