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Sensitizer‐Free Photon Upconversion in Single‐Component Brominated Aromatic Crystals
Author(s) -
Okumura Keisuke,
Matsuki Masaya,
Yamada Teppei,
Yanai Nobuhiro,
Kimizuka Nobuo
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201701769
Subject(s) - photon upconversion , absorption (acoustics) , photochemistry , chemistry , perylene , excited state , intersystem crossing , chromophore , anthracene , dopant , materials science , optoelectronics , atomic physics , doping , singlet state , physics , organic chemistry , molecule , composite material
A new methodology of single‐component photon upconversion (UC) based on S 0 ‐to‐T 1 (S−T) absorption is demonstrated. Although the S−T absorption is spin‐forbidden, modification of anthracene chromophores with heavy bromine atoms allows the direct population of the excited triplets in crystals upon near‐infrared (NIR) excitation with incident light intensities of ∼W cm −2 . The consequent triplet energy migration (TEM) and triplet‐triplet annihilation (TTA) events in crystals lead to blue UC emission with a large anti‐Stokes shift over 0.9 eV. The generality of the S−T absorption‐based UC is further confirmed with crystals of brominated perylene‐derivatives that show a green UC emission under a longer‐wavelength NIR excitation ( λ ex =856 nm). The single‐component UC with large anti‐Stokes shifts observed for brominated aromatic crystals compensates for the shortcomings of conventional two‐component solid UC system, i. e., energy losses intrinsic to the intersystem crossing of the sensitizers and the triplet energy transfer from sensitizer to emitter. It offers a simple and complementary UC methodology to the conventional two‐photon absorption (TPA) and TTA‐UC.