Photon Upconversion from Near-Infrared to Blue Light with TIPS-Anthracene as an Efficient Triplet–Triplet Annihilator

Abstract

Photon upconversion (PUC) via triplet-triplet annihilation (TTA) from near-infrared (NIR) to blue photons could have important applications especially to bio-imaging and drug delivery accompanied by photochemical reaction. The fundamental challenges in achieving this has been the large anti-Stokes shift combined with the need to efficiently sensitize within the biological transparency window (700-900 nm). This calls for materials combinations with minimal energy losses during sensitization and minimal energy requirements to drive efficient TTA. Here, we demonstrate efficient PUC converting from NIR energy to blue photons using the commercially available material 9,10-Bis[(triisopropylsilyl)ethynyl]anthracene (TIPS-Ac) as the annihilator. With a conventional triplet sensitizing system, TIPS-Ac performed TTA efficiency of 77 ± 3 % despite a relatively small driving force, compared to conventional TTA material converting from NIR to blue, for the TTA of less than 0.32 eV. Combined with Pt(II) meso-Tetraphenyl Tetrabenzoporphine (PtTPBP), which is a heavy atom triplet sensitizer that directly generates triplets upon NIR photon excitation, the resulting system allowed for an anti-Stokes shift of 1.03 eV. Our results highlight the use of direct triplet generation via NIR excitation as a useful path to achieving large anti-Stokes shift and also show that high TTA efficiencies can be achieved even in the absence of large driving energies for the TTA process.

Photon Upconverting Solid Films with Improved Efficiency for Endowing Perovskite Solar Cells with Near‐Infrared Sensitivity

“…This obtained value is comparable to the best NIR-to-vis TTA-UC solid systems, [25,30] and further improvement would be expected by increasing the statistical probability to obtain a singlet from two triplets through the control of higher triplet energy levels. [35,36] Generally, TTA-UC emission intensity shows a quadratic-tolinear transition with increasing excitation intensity, and the transition point gives a threshold excitation intensity (I th ). [37][38][39] Above I th , TTA becomes the main deactivation channel for the acceptor triplets.…”

Stimuli‐Responsive Molecular Photon Upconversion

“…Photon upconversion (UC) is ap rocess that converts lower-energy (longer-wavelength) into higher-energy (shorter-wavelength) photons.A mong different UC mechanisms such as two-photon absorption and multistep excitation of lanthanide nanoparticles,t riplet-triplet-annihilation-based UC (TTA-UC) has recently attracted considerable attention due to its high efficiency at relatively low excitation intensities.T he first report on TTA-UC by Parker and Hatchard dates back to 1962, [1] but it was less prevalent in the last century.A fter entering the 21st century,T TA-UC got renewed attention due to the urgent demands on renewable-energy production using sunlight. [2][3][4][5][6][7][8][9][10][11][12] Ther ecovery of wasted sub-band-gap photons through TTA-UC has the potential to improve the efficiencyo fa ll sunlight-powered devices represented by photovoltaics and photocatalysis, where the quantum yield and excitation intensity are the main parameters to evaluate the usefulness of TTA-UC. On the contrary,f or biological and environmental applications,t he stimuli-responsiveness of TTA-UC is in the spotlight.…”

In-Silico Prediction of Annihilators for Triplet Fusion Upconversion via Auxiliary-Field Quantum Monte Carlo

“…10 Thus far, there are few families of annihilators capable of emitting high energy blue to near-UV light. 4,11 These include 9,10 substituted anthracenes, 4,[12][13][14][15] para-terphenyl, 16 pyrene, 17 and 2,5-diphenyloxazole. 18,19 Enlarging the chemical space of high energy upconverting annihilators would therefore represent a significant advancement towards the widespread use of photon upconversion for a variety of applications.…”