Radical nanoparticles for photon upconversion Kieran D. Richards , John M. Hudson, Emrys W. Evans Department of Chemistry, Swansea University, Singleton Park, Swansea SA2 8PP, UK Radical-triplet systems provide an exciting new playground of energy levels for photon upconversion. 1 Photoexcited radical doublet states using low energy photons can directly sensitise triplet up-conversion states towards high energy photon emission (see figure). This provides an all-organic approach that allows greater harnessing of the visible spectrum for applications in solar technologies. Here we investigate nanoparticle environments from micellar scaffolds for radical-triplet systems. The micellar environment is intermediate to the solution and solid state, and can be tuned to exploit their favourable properties for upconversion. In this work we prepare doublet-triplet nanoparticles using TTM-1Cz radical (sensitiser) with diphenylanthracene (up-converter) and Brij 35 (surfactant). The structure, optical and magnetic properties of the radical nanoparticle systems are investigated to reveal structure-function properties for photon management through radical-triplet energy and spin transfer, with broad implications that span from optoelectronics to quantum materials.
Figure 1. Diagram showing doublet excitation of TTM-1Cz sensitiser, followed by doublet-triplet energy transfer to the diphenylanthracene (DPA) up-converter and the resulting emission. References 1. J. Han, Y. Jiang, A. Obolda, P. Duan, F. Li and M. Liu, The Journal of Physical Chemistry Letters , 2017, 8 , 5865–5870.
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