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Proceedings Paper

Broadband sensitized photon up-conversion at subsolar irradiance (Conference Presentation)
Author(s): Jacopo Pedrini; Angelo Monguzzi; Francesco Meinardi
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Paper Abstract

A crucial limit of solar devices is their inability to harvest the full solar spectrum. Currently, sensitized up-conversion based on triplet-tripled annihilation (STTA-UC) in bi-component organic systems is the most promising technique to recover sub-bandgap photons, showing good efficiencies also at excitation intensities comparable to the solar irradiance. In STTA-UC, high-energy light is generated through annihilation of metastable triplet states of molecules acting as emitters, which are populated via resonant energy transfer from a light-harvesting sensitizer. However, suitable sensitizers show narrow absorption bands, limiting the fraction of recoverable photons, therefore preventing the application of STTA-UC to real-world devices. Here we demonstrate how to overcome the described limit by using multiple sensitizers that work cooperatively to broaden the overall system absorption band. This is obtained using an additional sensitizer that transfers the extra harvested energy to the main one (sensitization of the sensitizer), or a set of properly designed complementary absorbing sensitizers all able to excite simultaneously the same emitter (multi-sensitizers). In both cases STTA-UC performances result strongly enhanced compared to the corresponding mono-sensitizer system, increasing the up-converted light intensity generated at AM 1.5 up to two times. Remarkably, by coupling our light converters to a DSSC we prove its operation by exploiting exclusively sub-bandgap photons. A detailed modeling of the photophysical processes involved in these complex systems allows us to draw the guidelines for the design of the next generation STTA-UC materials, encouraging their application to photovoltaic technologies.

Paper Details

Date Published: 2 November 2016
PDF: 1 pages
Proc. SPIE 9937, Next Generation Technologies for Solar Energy Conversion VII, 99370J (2 November 2016); doi: 10.1117/12.2236577
Show Author Affiliations
Jacopo Pedrini, Univ. degli Studi di Milano-Bicocca (Italy)
Angelo Monguzzi, Univ. degli Studi di Milano-Bicocca (Italy)
Francesco Meinardi, Univ. degli Studi di Milano Bicocca (Italy)

Published in SPIE Proceedings Vol. 9937:
Next Generation Technologies for Solar Energy Conversion VII
Oleg V. Sulima; Gavin Conibeer, Editor(s)

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