German-Irish research team sees kesterite grains being used for thin-film solar cells

Researchers at German research institute Helmholtz-Zentrum Berlin for Materials and Energy and the University of Limerick, Ireland have discovered a novel solid-state reaction that lets kesterite grains grow within a few seconds and at relatively low temperatures. The research could ultimately be used to produce thin microcrystalline semiconductor films without the need for expensive vacuum technology, and it could help improve the efficiency of thin-film solar cells using Cu2ZnSnS4-based kesterite semiconductors in place of Cu(In,Ga)Se2 chalcopyrite.
For the reaction, the researchers exploit a transition from a metastable wurtzite compound in the form of nanorods to the more stable kesterite compound. At the EDDI Beamline at BESSY II, the scientists could observe this process in real-time when heating the sample: in a few seconds kesterite grains formed. The size of the grains was found to depend on the heating rate. With fast heating, they succeeded in producing a kesterite thin film with near micrometer-sized crystal grains – the film could be used in thin-film solar cells. The researchers' findings have been published in the journal Nature Communications.

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