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Here, films using CdSe nanocrystal (NC) triplet photosensitizers in conjunction with diphenylanthracene (DPA) emitters were assembled to address several challenges to practical applications for solution-based photon upconversion. By using poly(9-vinylcarbazole) as a phosphorescent host in this film, volatile organic solvents are eliminated, the spontaneous crystallization of the emitter is significantly retarded, and ∼1.5% photon upconversion quantum yield (out of a maximum of 50%) is obtained. Transient absorption spectroscopy on nanosecond-to-microsecond time scales reveals this efficiency is enabled by an exceptionally long triplet lifetime of 3.4 ± 0.3 ms. Ultimately, we find the upconversion efficiency is limited by incomplete triplet–triplet annihilation, which occurs with a rate 3–4 orders of magnitude slower than in solution-phase upconversion systems.
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Superradiant and subradiant states in lifetime-limited organic molecules through laser-induced tuning
An array of radiatively coupled emitters provides a platform for generating, storing and manipulating quantum light. However, the simultaneous positioning and tuning of several lifetime-limited emitters into resonance remains a challenge. Here we report the creation of superradiant and subradiant entangled states in pairs of lifetime-limited and subwavelength-spaced organic molecules by permanently shifting them into resonance with laser-induced tuning. The molecules are embedded as defects in an organic nanocrystal. The pump light redistributes charges in the nanocrystal and dramatically increases the likelihood of resonant molecules. The frequency spectra, lifetimes and second-order correlation functions agree with a simple quantum model. This scalable tuning approach with organic molecules provides a pathway for observing collective quantum phenomena in subwavelength arrays of quantum emitters.
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- PAR ID:
- 10518012
- Publisher / Repository:
- Nature
- Date Published:
- Journal Name:
- Nature Physics
- Volume:
- 20
- Issue:
- 5
- ISSN:
- 1745-2473
- Page Range / eLocation ID:
- 836 to 842
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41567-024-02404-4
