AUTHOR=Caballero Raquel , Haass Stefan G. , Andres Christian , Arques Laia , Oliva Florian , Izquierdo-Roca Victor , Romanyuk Yaroslav E. 

TITLE=Effect of Magnesium Incorporation on Solution-Processed Kesterite Solar Cells

JOURNAL=Frontiers in Chemistry

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2018.00005

DOI=10.3389/fchem.2018.00005

ISSN=2296-2646

ABSTRACT=<p>The introduction of the alkaline-earth element Magnesium (Mg) into Cu<sub>2</sub>ZnSn(S,Se)<sub>4</sub> (CTZSSe) is explored in view of potential photovoltaic applications. Cu<sub>2</sub>Zn<sub>1−x</sub>Mg<sub>x</sub>Sn(S,Se)<sub>4</sub> absorber layers with variable Mg content <italic>x</italic> = 0…1 are deposited using the solution approach with dimethyl sulfoxide solvent followed by annealing in selenium atmosphere. For heavy Mg alloying with <italic>x</italic> = 0.55…1 the phase separation into Cu<sub>2</sub>SnSe<sub>3</sub>, MgSe<sub>2</sub>, MgSe and SnSe<sub>2</sub> occurs in agreement with literature predictions. A lower Mg content of <italic>x</italic> = 0.04 results in the kesterite phase as confirmed by XRD and Raman spectroscopy. A photoluminescence maximum is red-shifted by 0.02 eV as compared to the band-gap and a carrier concentration N<sub>CV</sub> of 1 × 10<sup>16</sup> cm<sup>−3</sup> is measured for a Mg-containing kesterite solar cell device. Raman spectroscopy indicates that structural defects can be reduced in Mg-containing absorbers as compared to the Mg-free reference samples, however the best device efficiency of 7.2% for a Mg-containing cell measured in this study is lower than those frequently reported for the conventional Na doping.</p>