Enhancing NIR-to-visible photon upconversion in cast solid by introducing bulky substituents in rubrene and by suppressing back energy transfer

Sawa, Akane; Shimada, Shinichi; Tripathi, Neeti; Heck, Claire; Tachibana, Hiroaki; Koyama, Emiko; Mizokuro, Toshiko; Hirao, Yasukazu; Kubo, Takashi; Tamai, Naoto; Kuzuhara, Daiki; Yamada, Hiroko; Kamada, Kei

doi:10.1039/d3tc00853c

Cited by 2 publications

(3 citation statements)

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“…It is known that quenching of emitter fluorescence by sensitizer doping can affect Φ UC . Thus, decreasing the sensitizer concentration might weaken the quenching and reduce the effect on Φ UC if the quenching has a dominant role.…”

Section: Resultsmentioning

confidence: 99%

“…It is known that quenching of emitter fluorescence by sensitizer doping can affect Φ UC . 27 Thus, decreasing the sensitizer concentration might weaken the quenching and reduce the effect on Φ UC if the quenching has a dominant role. The fluorescence quantum yield of DPA in the cast film (Φ FL ) was measured by changing the concentration of the sensitizer for the range of the molar ratio of [S]:[E] = 1:10 6 −1:10 3 where the concentration of the host DPA was fixed at [E] = 143 mM (Figure 8a).…”

Section: Energy Matching Condition For Tetmentioning

confidence: 99%

“…In the past decade, triplet–triplet annihilation (TTA) photon upconversion (UC), so-called TTA-UC, has attracted interest of researchers in many fields because of its high conversion efficiency and low operation light intensity. − Many applications including solar cell, photocatalysis, bioimaging, photopolymerization, and information display have been studied and demonstrated. − TTA-UC has developed in the solution system where the intermolecular interactions necessary for TTA-UC are assisted by molecular diffusion and collision. However, for the device applications, the solid system is favorable, and various types of solid TTA-UC systems have been reported recently. − Doped polymer was the first approach, but the slow diffusion in the polymer matrix limits UC efficiency even with low T g polymers. , Gel, which consists of a 3D polymer network filled with liquid, is an alternating approach. , Although solid in appearance, gel systems have a fast diffusion rate as solution and show the comparable performance to the solution system. The drawback of this approach is the dry-up of the liquid component and the necessity of sealing due to the use of volatile organic solvent.…”

Section: Introductionmentioning

confidence: 99%

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Solution to the Host–Guest Compatibility Problem of Solid Triplet–Triplet Annihilation Photon Upconversion by a Molecular-Anchor Sensitizer Approach

Fukuuchi,

Toyoshima,

Yoshinami

et al. 2024

J. Phys. Chem. C

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Efficient and uniform solid-state triplet−triplet annihilation photon upconversion (TTA-UC) is demonstrated by the solution cast film doped with the emitter-tethered sensitizer, in which the emitter part acts as a molecular anchor to control segregation of guest sensitizer molecules from the host matrix of emitter molecules on solidification. The tethered sensitizer, named as molecular-anchor sensitizer (MAS), was implemented as the supramolecules consisting of Pd-tetraphenylporphyrin (PdTPP) unit as the core and 4 or 8 units of 9,10-diphenylanthracene (DPA) tethered to the core with a flexible molecular chain. Saturated solution of DPA doped with a tiny amount of MAS (1:1000 or less in a molar ratio) was used for casting. The solid films fabricated from this solution showed good uniformity of upconversion (UC) emission. Most crystalline grains showed intense UC emission by 532 nm excitation, while a small number of crystalline grains showed UC emission for the film with a conventional (nontethered) sensitizer. The UC quantum yield (UC-QY, 50% basis) of the solid film with MAS was found to be 0.01−0.02 at a molar ratio of sensitizer to emitter of 1:1000. It was found that a decrease of the sensitizer concentration suppressed the fluorescence quenching of DPA by the sensitizer and the UC-QY increased to 0.13. The internal quantum yield, which is the quotient of doubled UC-QY divided by the fluorescence quantum yield, was found to depend on the number and length of the tether of MAS and to be close to unity for the sensitizers with fewer (4) and longer (C 6 ) tethers regardless of the kind. The concept of MAS opens a new way for further development of efficient solid TTA-UC systems by providing better compatibility between the sensitizer and the emitter in the solid matrix.

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Section: Resultsmentioning

confidence: 99%

Section: Energy Matching Condition For Tetmentioning

confidence: 99%