More Like this

1. Triplet-triplet annihilation photon-upconversion in hydrophilic media with biorelevant cholesteryl triplet energy acceptors

   https://doi.org/10.1016/j.jphotochem.2021.113412  

   Yun, Young Ju; Isokuortti, Jussi; Laaksonen, Timo; Durandin, Nikita; Ayitou, A. Jean-Luc (September 2021, Journal of Photochemistry and Photobiology A: Chemistry)
2. Triplet–Triplet Annihilation Upconversion in a Porphyrinic Molecular Container

   https://doi.org/10.1021/jacs.2c13846  

   Chen, Hongliang; Roy, Indranil; Myong, Michele S.; Seale, James S.; Cai, Kang; Jiao, Yang; Liu, Wenqi; Song, Bo; Zhang, Long; Zhao, Xingang; et al (May 2023, Journal of the American Chemical Society)
3. Efficient Triplet–Triplet Annihilation Upconversion in an Electroluminescence Device with a Fluorescent Sensitizer and a Triplet‐Diffusion Singlet‐Blocking Layer

   https://doi.org/10.1002/adma.201804850  

   Chen, Chia‐Hsun; Tierce, Nathan_T; Leung, Man‐kit; Chiu, Tien‐Lung; Lin, Chi‐Feng; Bardeen, Christopher_J; Lee, Jiun‐Haw (October 2018, Advanced Materials)

   Abstract Solid‐state triplet–triplet annihilation upconversion (TTAUC) blue emission in an electroluminescence device (i.e., an organic light‐emitting diode (OLED)) is demonstrated. A conventional green fluorophore, tris‐(8‐hydroxyquinoline)aluminum (Alq₃), is employed as the sensitizer that generates 75% triplet under electrical pumping for the blue triplet–triplet annihilation emitter, 9,10‐bis(2′‐naphthyl) anthracene (ADN), with the heterojunction bilayer structure. The operation lifetime is elongated both for ADN blue (4.1x) and Alq₃green (34.8%) emission due to efficient use of excitons and separation of recombination and emission zone. To reduce the singlet quenching (SQ) of blue TTAUC signal by the Alq₃sensitizer with lower bandgap, 1‐(2,5‐dimethyl‐4‐(1‐pyrenyl)phenyl)pyrene (DMPPP) is inserted between the Alq₃and ADN as a triplet‐diffusion‐and‐singlet‐blocking layer. DMPPP exhibits triplet energy close to Alq₃and higher than ADN, as well as higher singlet energy than both Alq₃and ADN. It allows triplet diffusion from Alq₃to ADN, but blocks the SQ of the blue TTAUC signal by Alq₃. 86.1% intrinsic efficiency of TTAUC is demonstrated in this trilayer (Alq₃/DMPPP/ADN) OLED. 

   more » « less
4. Triplet vinylnitrenes

   https://doi.org/10.1002/9780470682531.pat0925  

   Banerjee, U.; Thenna-Hewa, K.; Gudmundsdottir, A. D. (June 2019, Patai’s chemistry of functional groups)

   This chapter describes how intramolecular sensitization has been used to successfully form triplet vinylnitrene intermediates from vinyl azide, isoxazole, and azirine compounds. Triplet vinylnitrenes have been thoroughly characterized in cryogenic matrices using UV/vis absorption, infrared, and electron spin resonance spectroscopies. Electron spin resonance spectroscopy shows that vinylnitrenes have a significant 1,3‐biradical character, which is further supported by density functional theory calculations. Laser flash photolysis, which has allowed the direct detection of triplet vinylnitrenes in solution, reveals that they are short‐lived intermediates with lifetimes on the order of a few microseconds. Vinylnitrenes decay efficiently by intersystem crossing to form products because their 1,3‐biradical character renders their vinylic CC bond flexible, which enhances intersystem crossing. At cryogenic temperatures, flexible triplet vinylnitrenes are not stable and intersystem cross to form products. Nevertheless, triplet vinylnitrenes can be stabilized by limiting the flexibility of the vinylic CC bond, which renders them stabile in cryogenic matrices. Thus, they are promising building blocks for high‐spin assemblies. Furthermore, as stabilized vinylnitrenes can also be employed in bimolecular reactions, they have potential for use in various synthetical applications. 

   more » « less
5. Optical probes of the quantum-entangled triplet-triplet state in a heteroacene dimer

   https://doi.org/DOI: 10.1103/PhysRevB.98.165202  

   Khan, S.; Mazumdar, S. (October 2018, Physical review. B, Condensed matter)

   The nature and extent of the spin-entanglement in the triplet-triplet biexciton with total spin zero in correlated-electron π-conjugated systems continues to be an enigma. Differences in the ultrafast transient absorption spectra of free triplets versus the triplet-triplet can give a measure of the entanglement. This, however, requires theoretical understandings of transient absorptions from the optical spin-singlet, the lowest spin-triplet exciton, as well as from the triplet-triplet state, whose spectra are often overlapping and hence difficult to distinguish. We present a many-electron theory of the electronic structure of the triplet-triplet, and of complete wavelength-dependent excited state absorptions (ESAs) from all three states in a heteroacene dimer of interest in the field of intramolecular singlet fission. The theory allows direct comparisons of ESAs with existing experiments as well as experimental predictions, and gives physical understandings of transient absorptions within a pictorial exciton basis that can be carried over to other experimental systems. 

   more » « less