Influence of precursor sulfur content on film formation and compositional changes in Cu2ZnSnS4 films and solar cells
2012 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, Vol. 98, 110-117 p.Article in journal (Refereed) Published
Cu2ZnSnS4 (CZTS) thin films are made using sulfurisation of co-sputtered metallic and sulfur-containing precursor films. The CZTS grain size is larger for metallic precursors than for sulfur-containing precursors while more uniform films with fewer voids are obtained in the latter case. During sulfurisation of precursors with tin-excess in closed quartz ampoules, tin is lost from the films with greater losses from metallic precursors. We suggest that the reduced grain size and the reduced tin-loss for sulfur-containing precursors can be explained by a larger number of CZTS nuclei being formed early in the sulfurisation process. In sulfur containing precursors with large tin excess, SnS2 is observed together with CZTS, and a tin-rich bottom layer segregates. This indicates that tin-diffusion in CZTS is relatively slow. Solar cell devices made for a range of compositions at and around stoichiometric CZTS show highest efficiencies in two compositional groups; Zn-rich and Cu-poor/Sn-rich, while close to stoichiometric material gives poor devices. Devices including the tin-rich bottom layer show efficiencies of up to 3.2%. The role of secondary phases such as ZnS and SnS2 on device performance is discussed.
Place, publisher, year, edition, pages
2012. Vol. 98, 110-117 p.
CZTS, Kesterite, Sulfurisation, Solar cell
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject Engineering Science with specialization in Electronics
IdentifiersURN: urn:nbn:se:uu:diva-171401DOI: 10.1016/j.solmat.2011.10.019ISI: 000300536500014OAI: oai:DiVA.org:uu-171401DiVA: diva2:511134