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Efficient photon upconversion with a new emitter

Prof. Kenji KAMADA (Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), AIST Kansai Center, Japon) will give a lecture about "Efficient photon upconversion with a new emitter: from solution to binary solid fabricated by casting" in ENS Paris-Saclay.
Le 02/10/2017 : 14:00 à 16:00
Ajouter à mon agenda 2024-04-01 00:22:29 2024-04-01 00:22:29 Efficient photon upconversion with a new emitter Prof. Kenji KAMADA (Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), AIST Kansai Center, Japon) will give a lecture about "Efficient photon upconversion with a new emitter: from solution to binary solid fabricated by casting" in ENS Paris-Saclay. Chemla Amphitheater - ENS Paris-Saclay Campus ENS-PARIS-SACLAY webmaster@ens-paris-saclay.fr Europe/Paris public

Photon upconversion based on the triplet-triplet annihilation mechanism (TTA-UC) has been attracted considerable attention for the last several years because of its high quantum yield at low excitation intensity close to sunlight. 

For TTA-UC, two molecular species are needed: one is sensitizer absorbing the light and generate its triplet state with high quantum yield and the other is emitter whose triplets interact each other though TTA process and generate its excited singlet emitting a photon as delayed fluorescence.

Figure resume KAMADA.jpg

Among various combinations of the sensitizers and emitters, the pair of Pt-octaethylporphirin (PtOEP, sensitizer) and 9,10-diphenylanthracene (DPA, emitter) has been known to show one of the highest upconversion quantum yield (UC-QY), providing green(532 nm)-to-blue(430nm) upconversion. 

We have introduced the new emitter molecules having loop-like alkyl chains to cover the diphenylanthracene core (C7-sDPA, Fig. 1).  This emitter showed higher UC-QY than its parent molecule in solution. The process contributing to the high UC-QY is discussed.


Furthermore, TTA-UC in solid system, important for device applications, is presented with the molecules.  Previously, UC-QY was very limited in solid system because of the triplet energy transfer (TET) process was limited due to segregation of sensitizer from the emitter matrix. 

We developed rapid-drying casting method where the matrix of emitter solidified faster than the segregation of sensitizer molecules. The binary sold fabricated by this method  showed excellent upconversion properties.  Especially, with C7-sDPA, the low excitation intensity at the sunlight level and UC-QY around 20% was successfully achieved.

The results show that this approach is a promising method for developing efficient solar photon upconverter.

[1] K. Kamada, et al., Mater. Horiz., 2017, 4, 83.

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