Room-Temperature High-Efficiency Solid-State Triplet-Triplet Annihilation Up-Conversion in Amorphous Poly(olefin sulfone)s

Andrey Turshatov; Dmitry Busko; Natalia Kiseleva; Stephan L Grage; Ian A Howard; Bryce S Richards

doi:10.1021/acsami.6b12625

Room-Temperature High-Efficiency Solid-State Triplet-Triplet Annihilation Up-Conversion in Amorphous Poly(olefin sulfone)s

ACS Appl Mater Interfaces. 2017 Mar 8;9(9):8280-8286. doi: 10.1021/acsami.6b12625. Epub 2017 Feb 24.

Authors

Andrey Turshatov¹, Dmitry Busko¹, Natalia Kiseleva¹, Stephan L Grage², Ian A Howard^{1

3}, Bryce S Richards^{1

3}

Affiliations

¹ Karlsruhe Institute of Technology, Institute of Microstructure Technology , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
² Karlsruhe Institute of Technology, Institute of Biological Interfaces IBG-2 , P.O. Box 3640, 76021 Karlsruhe, Germany.
³ Karlsruhe Institute of Technology, Light Technology Institute , Engesserstrasse 13, 76131 Karlsruhe, Germany.

PMID: 28150940
DOI: 10.1021/acsami.6b12625

Abstract

Triplet-triplet annihilation up-conversion (TTA-UC) is a developing technology that can enable spectral conversion under sunlight. Previously, it was found that efficient TTA-UC can be realized in polymer hosts for temperatures above the polymer's glass transition (T > T_g). In contrast, TTA-UC with high quantum yield for temperatures below T_g is rarely reported. In this article, we report new polymer hosts in which efficient TTA-UC is observed well below T_g, when the polymer is in a fully solid state. The four poly(olefin sulfone) hosts were loaded with upconversion dyes, and absolute quantum yields of TTA-UC (η_TTA-UC) were measured. The highest value of η_TTA-UC = 2.1% was measured for poly(1-dodecene sulfone). Importantly, this value was the same in vacuum and at ambient conditions, indicating that the host material acts as a good oxygen barrier. We performed time-resolved luminescence experiments in order to elucidate the impact of elementary steps of TTA-UC. In addition to optical characterization, we used magic angle spinning solid-state NMR experiments to estimate the T2 transverse relaxation time. Relatively long T2 times measured for poly(olefin sulfone)s indicate an enhanced nanoscale fluidity in the studied (co)polymers, which unexpectedly coexists with a rigidity on the macroscale. This would explain the exceptional triplet energy transfer between the guest molecules, despite the macroscopic rigidity.

Keywords: T2 transverse relaxation time; poly(olefin sulfone); porphyrin; sensitized light up-conversion; triplet−triplet annihilation; triplet−triplet energy transfer.