Development of Cu(In,Ga)Se-2 superstrate devices with alternative buffer layers
2016 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 157, 85-92 p.Article in journal (Refereed) Published
Superstrate Cu(ln,Ga)Se-2 (CIGS) solar cells are prepared in the structure SLG/TCO/buffer/CIGS/Au with CIGS deposited onto the buffer layer by a single stage co-evaporation process. Three buffer materials - CdS deposited by chemical surface deposition, ZnSe and ZnO by RF magnetron sputtering - are tested in the superstrate structure. The best cell achieves 8.6% efficiency with the ZnO buffer after light soaking and forward bias treatments. The efficiency of devices with CdS or ZnSe buffers are less than 4%. The junction formation between the absorber and buffer layers are investigated by x-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. For CdS/CIGS and ZnSe/CIGS superstrate devices extensive inter-diffusion between the absorber and buffer layer under CIGS growth condition is the critical problem. For ZnO/CIGS superstrate cells GaxOy formation at the junction interface and unfavorable conduction band alignment are the main factors that limit the device performance.
Place, publisher, year, edition, pages
2016. Vol. 157, 85-92 p.
CIGS, Solar cell, Thin film, Superstrate, Alternative buffer, Interface
Materials Engineering Environmental Engineering
IdentifiersURN: urn:nbn:se:uu:diva-306233DOI: 10.1016/j.solmat.2016.05.018ISI: 000384391700012OAI: oai:DiVA.org:uu-306233DiVA: diva2:1040363