Efficiency of Noncoherent Photon Upconversion by Triplet–Triplet Annihilation: The C60 Plus Anthanthrene System and the Importance of Tuning the Triplet Energies

Sugunan, Sunish K.; Greenwald, Chelsea; Paige, Matthew F.; Steer, Ronald P.

doi:10.1021/jp404587u

Cited by 29 publications

(32 citation statements)

References 52 publications

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“…The free-energy change involved in an electron transfer process from the triplet state of the photosensitizer to DPA is calculated to be positive, thus, the electron transfer can be excluded for the cause of the emission quenching in Pt-DPA. The slight difference of the upconverted fluorescence from that of DPA-OH is caused by the inner filter effect owing to the relatively high concentration of DPA-OH in the TTA-UC system, which is similar to that reported in literatures 30,31 . Therefore, the emission quenching in Pt-DPA can be ascribed to the exothermic TTET from the photosensitizer to the DPA acceptor, which is further strengthened by the transient absorption measurements.…”

Section: Steady-state Absorption and Emission Propertiessupporting

confidence: 88%

Intramolecular triplet–triplet energy transfer enhanced triplet–triplet annihilation upconversion with a short-lived triplet state platinum(ii) terpyridyl acetylide photosensitizer

Zeng

Chen

et al. 2015

RSC Adv.

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A model of dendritic compound (Pt-DPA) with two Pt-complex photosensitizer chromophores and two 9,10diphenylanthracene (DPA) acceptor groups covalently attached to the periphery and the core of the poly(aryl ether) dendrimer of generation 1 was prepared. A triplet-triplet annihilation upconversion (TTA-UC) system (Pt-DPA/DPA-OH) was constructed in deaerated DMF by combining Pt-DPA with a dissociative acceptor (DPA-OH). Although the lifetime of the triplet state of Pt-complex is only 52 ns, the upconversion fluorescence from DPA (400 ~ 460 nm) in the Pt-DPA/DPA-OH system was observed with quantum yield of 0.22% upon selective excitation of the Pt-complex with a 473 nm laser, which is due to the efficient intramolecular triplet-triplet energy transfer (Φ TTET > 0.81) from the Pt-complex photosensitizer to the DPA acceptor within Pt-DPA. The acceptor covalently linked with the photosensitizer acts as an energy-relay to transfer the harvested energy to the dissociative acceptor which further undergoes the TTA process. The efficient intramolecular triplet-triplet energy transfer process between the photosensitizer and the acceptor plays an important role for the TTA-UC system building with a short-lived triplet state photosensitizer, which facilitates the production of the triplet state of the acceptor, thus advancing the TTA-UC process. This work presents a new strategy for construction of efficient TTA-UC systems utilizing short-lived triplet state photosensitizers.

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Section: Steady-state Absorption and Emission Propertiessupporting

confidence: 88%

Intramolecular triplet–triplet energy transfer enhanced triplet–triplet annihilation upconversion with a short-lived triplet state platinum(ii) terpyridyl acetylide photosensitizer

Zeng

Chen

et al. 2015

RSC Adv.

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“…In spite of extensive, creative research in the field of solar photovoltaics (SPV), the efficiencies of single-junction SPV devices remain limited by the mismatch between the solar emission spectrum and the absorption spectrum/band gap of the materials employed. [1][2][3][4][5] One of the cutting-edge efforts in SPV research therefore involves developing photon-managing processes that circumvent this fundamental limitation. Non-coherent photon upconversion (NCPU) by triplet-triplet annihilation (TTA) is one of the most promising of these avenues of research.…”

Section: Introductionmentioning

confidence: 99%

“…Non-coherent photon upconversion (NCPU) by triplet-triplet annihilation (TTA) is one of the most promising of these avenues of research. [1][2][3][4][5][6][7][8][9][10][11][12][13] In the usual case, NCPU-TTA consists of a series of photophysical events beginning with the harvesting of low-energy photons by a sensitizer that undergoes efficient intersystem crossing (ISC) to its lowest triplet state. This is then followed by triplet−triplet energy transfer (TTET) to a non-absorbing but highly fluorescent acceptor with a long-lived triplet state and a large S1 -T1 energy gap.…”

Section: Introductionmentioning

confidence: 99%

“…6,9,12 In explorations of processes that might improve the overall efficiency of NCPU-TTA, our groups have shown that homo-molecular NCPU-TTA in molecules such as d 0 or d 10 metalloporphyrins (MPs) that have unusually long-lived second excited singlet (S 2 ) states may prove useful. 5,[14][15][16][17] Homo-molecular NCPU-TTA involves photoexcitation of the porphyrin in its Q band, which in MPs with extended  electron systems can extend well into the near infrared.…”

Section: Introductionmentioning

confidence: 99%

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Determinants of the efficiency of photon upconversion by triplet–triplet annihilation in the solid state: zinc porphyrin derivatives in PVA

Rautela

Joshi

Novakovic

et al. 2017

Phys. Chem. Chem. Phys.

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Spectroscopic, photophysical and computational studies designed to expose and explain the differences in the efficiencies of non-coherent photon upconversion (NCPU) by triplet-triplet annihilation (TTA) have been carried out for a new series of alkyl-substituted diphenyl and tetraphenyl zinc porphyrins, both in fluid solution and in solid films. Systematic variations in the alkyl-substitution of the phenyl groups in both the di- and tetraphenyl porphyrins introduces small, but well-understood changes in their spectroscopic and photophysical properties and in their TTA efficiencies. In degassed toluene solution TTA occurs for all derivatives and produces the fluorescent S product states in all cases. In PVA matrices, however, none of the di-phenylporphyrins exhibit measurable NCPU whereas all the tetraphenyl-substituted compounds remain upconversion-active. In PVA the NCPU efficiencies of the zinc tetraphenylporphyrins vary significantly with their steric characteristics; the most sterically crowded tetraphenyl derivative exhibits the greatest efficiency. DFT-D computations have been undertaken and help reveal the sources of these differences.

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“…C 60 is a distinguished triplet converter, with a converting efficiency close to unity. Using C 60 as the photosensitizer and anthanthrene as the annihilator, a green‐to‐blue UC was realized in both toluene solution and PMMA films, as evidenced by the detected short‐wavelength fluorescence emission . Nevertheless, the main drawback of C 60 was its very weak absorption in the visible region.…”

Section: Metal‐free Organic Triplet Photosensitizersmentioning

confidence: 99%

New Bichromophoric Triplet Photosensitizer Designs and Their Application in Triplet–Triplet Annihilation Upconversion

Guo

Liu

Chen

et al. 2018

Advanced Optical Materials

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the distinctive advantage of using noncoherent light as the excitation source. Hence, the TTA-based photon upconversion (UC) is promised with a wider range of applications, such as harvesting the much abundant low-energy photons in the solar spectral irradiation and converting them to usable photons in photovoltaic devices. [4,5] Moreover, the development of TTA UC is also driven by the potential applications pertinent to photocatalysis and bio-technologies. [6][7][8][9] The two main functional components in a TTA UC system are the triplet photosensitizer and annihilator, the latter of which also serves as the emitter. While only a limited number of annihilators have so far been identified capable of efficient TTA upconverted emission, remarkable progress has been made with the design and investigation of photosensitizers in the past decade. A range of transitionmetal complexes and organic structures have been studied as potent photosensitizers. By virtue of all the various sensitizers that have been developed, a wide range of photon energy, ranging from visible to near-infrared, can now be used and upconverted by the TTA systems reported in the literature. [10,11] Furthermore, different types of materials, including various solvents, gels, polymers, have been employed as matrices to perform TTA UC, and even matrix-free conditions have been reported. [11][12][13][14][15] Mechanism of TTA UCThe streamlined mechanistic steps in a TTA UC are summarized in Figure 1. [16] In a typical bi-component system, upon absorbing a low-energy photon, the photosensitizer is excited into a singlet excited state before undergoing inter-system crossing (ISC) to the triplet state. Then, an intermolecular triplet-triplet energy transfer (TTET) takes place between the excited sensitizer and a nearby annihilator, regenerating the ground-state sensitizer along with an annihilator triplet. Since the annihilators are usually organic hydrocarbon molecules with spin-forbidden triplet-to-singlet relaxations, long-lived annihilator triplets thus accumulate over time, until bimolecular triplet-triplet annihilation takes place and generates a As indispensable molecular components, photosensitizers play a crucial role in determining the quantum efficiency of triplet-triplet annihilation upconversion (TTA UC). This emergent technology has attracted great attention in recent years for realizing large anti-Stokes shifts with noncoherent excitation sources. In a typical TTA UC, low-energy photons are first harvested by the photosensitizers, which upon intersystem crossing (ISC) undergo triplettriplet energy transfer (TTET) to emitters (i.e., annihilators). Following the bimolecular TTA among the emitters, high-energy photons are given off by the singlet excited state of the emitters. Apparently, the efficiencies of photon absorption, ISC, and TTET are all dependent on the sensitizers. With a Dextertype ET mechanism requiring collisional interactions, a long triplet lifetime of the energy donor (photosensitizer) is evidently favorable for enhancing ...

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Efficiency of Noncoherent Photon Upconversion by Triplet–Triplet Annihilation: The C60 Plus Anthanthrene System and the Importance of Tuning the Triplet Energies

Cited by 29 publications

References 52 publications

Intramolecular triplet–triplet energy transfer enhanced triplet–triplet annihilation upconversion with a short-lived triplet state platinum(ii) terpyridyl acetylide photosensitizer

Intramolecular triplet–triplet energy transfer enhanced triplet–triplet annihilation upconversion with a short-lived triplet state platinum(ii) terpyridyl acetylide photosensitizer

Determinants of the efficiency of photon upconversion by triplet–triplet annihilation in the solid state: zinc porphyrin derivatives in PVA

New Bichromophoric Triplet Photosensitizer Designs and Their Application in Triplet–Triplet Annihilation Upconversion

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