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Abstract Triplet‐triplet annihilation upconversion (TTA‐UC) is a photophysical process in which two low‐energy photons are converted into one higher‐energy photon. This type of upconversion requires two species: a sensitizer that absorbs low‐energy light and transfers its energy to an annihilator, which emits higher‐energy light after TTA. In spite of the multitude of applications of TTA‐UC, few families of annihilators have been explored. In this work, we show dipyrrolonaphthyridinediones (DPNDs) can act as annihilators in TTA‐UC. We found that structural changes to DPND dramatically increase its upconversion quantum yield (UCQY). Our optimized DPND annihilator demonstrates a high maximum internal UCQY of 9.4 %, outperforming the UCQY of commonly used near‐infrared‐to‐visible annihilator rubrene by almost double.
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Putting the “P” Back in Delayed Fluorescence – Silylethynyl Substitution Generates Efficient Pyrene Annihilators for Red‐to‐Blue Photon Upconversion
Abstract Triplet‐triplet annihilation photon upconversion (TTA‐UC) converts low‐energy photons to higher‐energy ones under low‐intensity incoherent excitation, thus enabling applications in fields ranging from medicine to solar energy conversion. Silylethynyl mono‐ and di‐substitution of acenes offers an attractive route to creating new annihilators that operate with minimal energy loss. Here, it is demonstrated that this approach can be extended to pyrene, yielding annihilators that display efficient red‐to‐blue upconversion. While pyrene is the namesake of P‐type delayed fluorescence, the original name for triplet‐triplet annihilation, it is known to be a poor annihilator due to its propensity for forming excimers. By tetra‐substituting pyrene with silylethynyl groups, excimer formation is substantially hindered while simultaneously minimizing the energy gap between the singlet and triplet pair states that participate in TTA‐UC, yielding outstanding annihilators for red‐to‐blue upconversion that operate with quantum yields of upward of 19% (29% when corrected for inner filter effects). Further, it is found that reducing the bulkiness of the silyl substituents is key to achieving high TTA‐UC quantum yields, which highlights the importance of annihilator side group selection when optimizing photon upconversion.
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- Award ID(s):
- 2155017
- PAR ID:
- 10600149
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 13
- Issue:
- 18
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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