Current matching limits the commercialization of tandem solar cells due to their instability over spectral changes, leading to the need of using solar concentrators and trackers to keep the spectrum stable. We demonstrate that voltage-matched systems show far higher performance over spectral changes; caused by clouds, dust and other variations in atmospheric conditions.
Singlet fission is a process in organic semiconductors which has shown very efficient, 200%, down-conversion yield and the generated excitations are long-lived, ideal for solar cells. As a result, the number of publications has grown exponentially in the past 5 years. Yet, so far no one has achieved to combine singlet fission with most low bandgap semiconductors, including crystalline silicon, the dominating solar cell material with a 90% share of the PV Market.
Here we show that singlet fission can facilitate the fabrication of voltage-matched systems, opening a simple design route for the effective implementation of down-conversion in commercially available photovoltaic technologies, with no modification of the electronic circuitry of such.
The implemention of singlet fission is achieved simply by decoupling the fabrication of the individual subcells. For this demonstration we used an ITO/PEDOT/P3HT/Pentacene/C60/Ag wide-bandgap subcell, and a commercial silicon solar cell as the low-bandgap component. We show that the combination of the two leads to the first tandem silicon solar cell which exceeds 100% external quantum efficiency.
Luis M. Pazos, Jumin Lee, Anton Kirch, Maxim Tabachnyk, Richard H. Friend, and Bruno Ehrler, "Singlet fission/silicon solar cell exceeding 100% EQE
(Conference Presentation)," Proc. SPIE 9923, Physical Chemistry of Interfaces and Nanomaterials XV, 992313 (Presented at SPIE Nanoscience + Engineering: August 30, 2016; Published: 10 November 2016); https://doi.org/10.1117/12.2238225.5161498050001.
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