Recombination in polymer-fullerene bulk heterojunction solar cells
TLDR
In this article, the authors show that the recombination kinetics of polymer BHJ cells evolve from first-order recombination at short circuit to bimolecular recombinations at open circuit as a result of increasing the voltage-dependent charge carrier density in the cell.Abstract:
Recombination of photogenerated charge carriers in polymer bulk heterojunction (BHJ) solar cells reduces the short circuit current $({J}_{sc})$ and the fill factor (FF). Identifying the mechanism of recombination is, therefore, fundamentally important for increasing the power conversion efficiency. Light intensity and temperature-dependent current-voltage measurements on polymer BHJ cells made from a variety of different semiconducting polymers and fullerenes show that the recombination kinetics are voltage dependent and evolve from first-order recombination at short circuit to bimolecular recombination at open circuit as a result of increasing the voltage-dependent charge carrier density in the cell. The ``missing 0.3 V'' inferred from comparison of the band gaps of the bulk heterojunction materials and the measured open-circuit voltage at room-temperature results from the temperature dependence of the quasi-Fermi levels in the polymer and fullerene domains---a conclusion based on the fundamental statistics of fermions.read more
Citations
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References
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MonographDOI
Hydrogenated amorphous silicon
TL;DR: In this article, the electronic density of states of amorphous silicon and their electronic states have been investigated in terms of defect reactions, thermal equilibrium and metastability, as well as their electronic properties.