Improving triplet-triplet-annihilation based upconversion systems by tuning their topological structure

Journal Article · Fri Nov 14 04:00:00 EST 2014 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4901336· OSTI ID:22415337

Zimmermann, Jochen; Wellens, Thomas; Buchleitner, Andreas ^[1]; Mulet, Roberto ^[1]; Scholes, Gregory D. ^[1]

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1. Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg (Germany)

Materials capable to perform upconversion of light transform the photon spectrum and can be used to increase the efficiency of solar cells by upconverting sub-bandgap photons, increasing the density of photons able to generate an electron-hole pair in the cell. Incoherent solar radiation suffices to activate upconverters based on sensitized triplet-triplet annihilation, which makes them particularly suited for this task. This process requires two molecular species, sensitizers absorbing low energy photons, and emitters generating higher frequency photons. Successful implementations exist in solutions and solids. However, solid upconverters exhibit lower efficiency than those in solution, which poses a serious problem for real applications. In the present work, we suggest a new strategy to increase the efficiency of sensitized upconverters that exploits the solid nature of the material. We show that an upconversion model system with molecules distributed as clusters outperforms a system with a random distribution of molecules, as used in current upconverters. Our simulations reveal a high potential for improvement of upconverter systems by exploring different structural configurations of the molecules. The implementation of advanced structures can push the performance of solid upconverters further towards the theoretical limit and a step closer to technological application of low power upconversion.

• OSTI ID: 22415337
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 18 Vol. 141; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANNIHILATION
DENSITY
EFFICIENCY
MOLECULES
PHOTONS
SENSITIZERS
SIMULATION
SOLAR CELLS
SOLAR RADIATION
SOLIDS
SOLUTIONS
SPECTRA
TRIPLETS