Triplet–Triplet Annihilation Photopolymerization for High-Resolution 3D Printing

Limberg, David; Kang, Ji‐Hwan; Hayward, Ryan C.

doi:10.1021/jacs.1c11022

Cited by 74 publications

(80 citation statements)

References 62 publications

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“…As a quadratic process, similar to TPP, TTA-UC is found to be able to trigger photopolymerization only at the focal point of the excitation beam (Figure c,d) . The first example of TTA-UC mediated 3D printing utilized the pair of palladium(II) octaethylporphine (PdOEP) and 9,10-diphenylanthracene (DPA), which converts green light to blue light, to give 3D printing features as small as 0.6 ± 0.1 μm with a continuous green LED as excitation source (∼10 W cm –2 ). , In order to realize volumetric 3D printing with TTA-UC, systematic control over the threshold behavior of the upconversion materials is crucial since the quadratic relationship between input excitation and upconverted emission only exists below the threshold value. Furthermore, different printing schemes need distinct upconversion thresholds whereas a lower threshold is favorable for low-fluence rapid parallelized printing (Figure e) .…”

Section: New Applications Of Highly Efficient Nir Tta-ucmentioning

confidence: 99%

“…More interestingly, this reductive 1 [TTBP]* can be utilized to trigger the polymer- Very recently, TTA-UC has also been reported to be used for photopolymerization-based 3D printing. 18,19,43 Traditionally, to obtain high-resolution photopolymerization-based 3D printing, the technology of two photon polymerization (TPP) was required to be utilized because polymerization can be confined to the focal point of the pulsed laser light (60−100 nm in dimension). 44 However, the high power of the required femtosecond laser pulses (∼10 12 W cm −2 ) can lead to highcost of commercial instruments and limited print size and speed, which prevent the widespread application.…”

Section: Tta-uc Mediated Photoredox Catalysismentioning

confidence: 99%

“…Very recently, the application of TTA-UC in photopolymerization-based threedimensional (3D) printing was reported. TTA-UC pairs that convert green light to blue light 18 or red light to blue light 19 were utilized to activate the photoinitiator and then trigger the polymerization with low power-density excitation (as low as 4 mW cm −2 ) from continuous LEDs (Figure 1h). Compared to two-photon polymerization, this TTA-UC mediated quadratic polymerization strategy realized volumetric 3D printing at several orders of magnitude lower power density (∼10 W cm −2 vs 10 12 W cm −2 ) with sub-micrometer resolution, indicating great application prospects.…”

Section: Introductionmentioning

confidence: 99%

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Enhancing Triplet–Triplet Annihilation Upconversion: From Molecular Design to Present Applications

et al. 2022

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Metrics & MoreArticle Recommendations CONSPECTUS: Photon upconversion, the process of converting lowenergy photons into high-energy ones, has been widely applied for solar energy conversion, photoredox catalysis, and various biological applications such as background-free bioimaging, cancer therapy, and optogenetics. Upconversion materials that are based on triplet−triplet annihilation (TTA) are of particular interest due to their low excitation power requirements (e.g., ambient sunlight) and easily tunable excitation and emission wavelengths. Despite advances that have been made with respect to TTA upconversion (TTA-UC) in the past decade, several challenges remain for near-infrared light-activatable triplet−triplet annihilation upconversion (NIR TTA-UC). These challenges include low upconversion quantum yield, small anti-Stokes shift, and incompatibility with oxygen, the latter of which seriously limits the practical applications of NIR TTA-UC. This Account will summarize the recent research endeavors to address the above-mentioned challenges and the recent new applications. The first part of this Account highlights recent strategies of molecular design to modulate the excited states of photosensitizers and annihilators, two key factors to determine TTA-UC performance. Novel molecular engineering strategies such as the resonance energy transfer method, dimerization of dye units, and the helix twist molecular structure have been proposed to tune the excited states of photosensitizers. The obtained photosensitizers exhibited enhanced absorption of deep tissue penetrable near-infrared (NIR) light, produced a triplet excited state with elevated energy level and prolonged lifetime, and promoted intersystem crossing, leading to an upgraded TTA-UC system with significantly expanded anti-Stokes shift. With respect to the annihilator, the perylene derivatives were systematically explored, and their attached aromatic groups were found to be the key to adjusting the energy levels of both the triplet and singlet excited states. The resultant optimal TTA-UC system exhibits the highest recorded efficiency among NIR TTA-UC systems. Moreover, to resolve the oxygen-induced TTA-UC quenching, enzymatic reactions were recently introduced. More specifically, the glucose oxidase-catalyzed glucose oxidation reaction showed the ability to rapidly consume oxygen to turn on the TTA-UC luminescence in an aqueous solution. The resultant TTA-UC nanoparticle was able to detect glucose and an enzyme related to glucose metabolism in a highly specific, sensitive, and background-free manner. Further, the upconverted singlet excited state of the annihilator was directly utilized as the catalyst or the excited substrate. For example, the modification of annihilators and drug molecules with photolabile linkages can realize the long wavelength light-induced photolysis. Compared to direct short-wavelength-driven photolysis, this sensitized TTA photolysis (TTAP) exhibits superior reaction yield and lower photodamage, which are important in the releas...

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Section: New Applications Of Highly Efficient Nir Tta-ucmentioning

confidence: 99%

Section: Tta-uc Mediated Photoredox Catalysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhancing Triplet–Triplet Annihilation Upconversion: From Molecular Design to Present Applications

et al. 2022

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“…This property has been leveraged to demonstrate TTA-UC-enabled volumetric 3D printing using violet or blue upconverted light. [29][30][31][32] The TTA-UC process is illustrated in Fig. 1A.…”

Section: Mainmentioning

confidence: 99%

Spatially Controlled UV Light Generation at Depth Using Upconversion Micelles

Zhou

Wirtz

Schloemer

et al. 2022

Preprint

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Ultraviolet (UV) light can trigger a plethora of useful photochemical reactions for diverse applications, including photocatalysis, photopolymerization, and drug delivery. These applications typically require penetration of high energy photons deep into materials, yet delivering these photons beyond the surface is extremely challenging due to absorption and scattering effects. Triplet-triplet annihilation upconversion (TTA-UC) shows great promise to circumvent this issue by generating high energy photons from incident lower energy photons. However, molecules that facilitate TTA-UC usually have poor water solubility, limiting their deployment in aqueous environments. To address this challenge, we leverage a nanoencapsulation method to fabricate water-compatible UC micelles, enabling on-demand UV photon generation deep into materials. We present two iridium-based complexes for use as TTA-UC sensitizers with increased solubilities that facilitate the formation of highly emissive UV-upconverting micelles. Furthermore, we show this encapsulation method is generalizable to nineteen UV-emitting UC systems, accessing a range of upconverted UV emission profiles with wavelengths as low as 350 nm. As a proof-of-principle demonstration of precision photochemistry at depth, we use UV-emitting UC micelles to photolyze a fluorophore at a focal point nearly a centimeter beyond the surface, revealing opportunities for spatially controlled manipulation deep into UV-responsive materials.

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“…Remarkably, the excitation power densities of these TTA-UC-assisted 3D printings were several orders of magnitude lower than those of two-photon-based 3D printings. Notably, when this article was under review, the Hayward group also found that porphyrin-based TTAP (entry 5 in Table 2 ) could be effectively utilized for high-resolution 3D printing (~100 nm) [ 96 ]. Doubtlessly, these studies not only present new applications for TTA-UC but also provide a novel approach for high-resolution 3D printing.…”

Section: Photochemistry Of Porphyrin-based Tta-uc For Chemical Transf...mentioning

confidence: 99%

Recent Advances in the Photoreactions Triggered by Porphyrin-Based Triplet–Triplet Annihilation Upconversion Systems: Molecular Innovations and Nanoarchitectonics

Yao¹,

Sun²,

He³

et al. 2022

IJMS

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Triplet–triplet annihilation upconversion (TTA-UC) is a very promising technology that could be used to convert low-energy photons to high-energy ones and has been proven to be of great value in various areas. Porphyrins have the characteristics of high molar absorbance, can form a complex with different metal ions and a high proportion of triplet states as well as tunable structures, and thus they are important sensitizers for TTA-UC. Porphyrin-based TTA-UC plays a pivotal role in the TTA-UC systems and has been widely used in many fields such as solar cells, sensing and circularly polarized luminescence. In recent years, applications of porphyrin-based TTA-UC systems for photoinduced reactions have emerged, but have been paid little attention. As a consequence, this review paid close attention to the recent advances in the photoreactions triggered by porphyrin-based TTA-UC systems. First of all, the photochemistry of porphyrin-based TTA-UC for chemical transformations, such as photoisomerization, photocatalytic synthesis, photopolymerization, photodegradation and photochemical/photoelectrochemical water splitting, was discussed in detail, which revealed the different mechanisms of TTA-UC and methods with which to carry out reasonable molecular innovations and nanoarchitectonics to solve the existing problems in practical application. Subsequently, photoreactions driven by porphyrin-based TTA-UC for biomedical applications were demonstrated. Finally, the future developments of porphyrin-based TTA-UC systems for photoreactions were briefly discussed.

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Triplet–Triplet Annihilation Photopolymerization for High-Resolution 3D Printing

Cited by 74 publications

References 62 publications

Enhancing Triplet–Triplet Annihilation Upconversion: From Molecular Design to Present Applications

Enhancing Triplet–Triplet Annihilation Upconversion: From Molecular Design to Present Applications

Spatially Controlled UV Light Generation at Depth Using Upconversion Micelles

Recent Advances in the Photoreactions Triggered by Porphyrin-Based Triplet–Triplet Annihilation Upconversion Systems: Molecular Innovations and Nanoarchitectonics

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