Bioimaging and biodetection assisted with TTA-UC materials

Near‐Infrared PhotoInitiating Systems: Photothermal versus Triplet–Triplet Annihilation‐Based Upconversion Polymerization

“…Triplet–triplet annihilation (TTA), rare‐earth ion (lanthanide) upconversion (UC), and two‐photon absorption (TPA) constitutes the three main upconversion processes known at present. [ 15 ] TTA‐UC is based on nonlinear anti‐Stokes shift process. Indeed, the TTA bimolecular mechanism, known since the beginning of the 1960s, [ 16 ] is based on the emission of a photon at a higher energy than the energy of the incident photon.…”

“…Concerning the chemical compounds involved in TTA‐UC when applied to photopolymerization, the sensitizer needs to have a sufficient solubility in the solvent/monomer used, should be carefully selected to greatly absorb around the emission wavelength of the irradiation source and should exhibit a small energy gap between the singlet and the triplet excited sate, as well as an efficient intersystem crossing. [ 15 ] To the best of our knowledge, a large majority of the sensitizers reported in the literature contains heavy metals such as palladium (Pd), platinum (Pt) but also zinc (Zn) among others. [ 1,4,21 ] This might be considered as a brake on development in polymer chemistry, as this type of chemistry does not have a lot of industrial prospects and is still underrepresented in applications.…”

“…Choice of polycyclic aromatic hydrocarbon compounds as annihilator is commonly done in the literature, and anthracenes or tetracenes can be cited as the most common structures. [ 15,17,19,25 ]…”

“…Two photoinitiating systems (PISs) have been tested: a generally used Type I photoinitiator, [ 26 ] Irgacure 784 (I784), and a Type II photoinitiator, [ 26 ] camphorquinone (CQ) combined with ethyl 4‐dimethylaminobenzoate (EDB). Concerning the annihilators, three molecules have been chosen based on the literature: 2,5,8,11‐tetra‐ tert ‐butylperylene (TTBP), [ 17,27 ] 1‐Chloro‐9,10‐ bis (phenylethynyl)anthracene (1‐CBPEA), [ 15,28 ] and perylene. [ 15,29 ] The results presented here are focused on three different sensitizers: 1‐butyl‐2‐(2‐[3‐[2‐(1‐butyl‐3,3‐dimethyl‐1,3‐dihydro‐indol‐2‐ylidene]‐diphenylamino‐cyclopent‐1‐enyl]‐vinyl)‐3,3‐dimethyl‐3 H ‐indolium tetrafluoroborate (S2025), 2‐[2‐[3‐[2‐(1,3‐dihydro‐1,3,3‐trimethyl‐2 H ‐indol‐2‐ylidene)‐ethylidene]‐2‐(1‐phenyl‐1 H ‐tetrazol‐5‐ylsulfanyl)‐1‐cyclohexen‐1‐yl]‐ethenyl]‐1,3,3‐trimethyl‐3 H ‐indolium chloride (S0507) and a Bodipy derivative.…”

Preparation and application of solid-state upconversion materials based on sodium polyacrylate

“…Upconversion is a phenomenon of lower-energy (longer wavelength) photons converted into higher-energy photons (shorter wavelength), which can be carried out by either two-photon absorption excited by the illuminant with high power density [1][2][3] or triplet-triplet annihilation (TTA) excited with low power density. [4][5][6][7] Owing to the potential widespread practical applications such as in photovoltaics, 8,9 photocatalysis 10,11 / photodegradation, 12,13 photodynamic therapy of cancer 14,15 and displays, 16 triplet-triplet annihilation upconversion (TTA-UC) has attracted more attention.…”