Improved Rear Surface Passivation of Cu(In,Ga)Se2 Solar Cells: A Combination of an Al2O3 Rear Surface Passivation Layer and Nano-Sized Local Rear Point Contacts
2014 (English)In: IEEE Journal of Photovoltaics, ISSN 2156-3381, Vol. 4, no 1, 486-492 p.Article in journal (Refereed) Published
An innovative rear contacting structure for copper indium gallium (di) selenide (CIGS) thin-film solar cells is developed in an industrially viable way and demonstrated in tangible devices. The idea stems from the silicon (Si) industry, where rear surface passivation layers are combined with micron-sized local point contacts to boost the open-circuit voltage (VOC) and, hence, cell efficiency. However, compared with Si solar cells, CIGS solar cell minority carrier diffusion lengths are several orders lower in magnitude. Therefore, the proposed CIGS cell design reduces rear surface recombination by combining a rear surface passivation layer and nanosized local point contacts. Atomic layer deposition of Al2O3 is used to passivate the CIGS surface and the formation of nanosphere-shaped precipitates in chemical bath deposition of CdS to generate nanosized point contact openings. The manufactured Al2O3 rear surface passivated CIGS solar cells with nanosized local rear point contacts show a significant improvement in VOC compared with unpassivated reference cells.
Place, publisher, year, edition, pages
2014. Vol. 4, no 1, 486-492 p.
Research subject Engineering Science with specialization in Electronics; Engineering Science with specialization in Solid State Physics
IdentifiersURN: urn:nbn:se:uu:diva-219898DOI: 10.1109/JPHOTOV.2013.2287769OAI: oai:DiVA.org:uu-219898DiVA: diva2:703427
ProjectsSolar cells, Photovoltaics, Si, PERC, PERL, Thin film, Cu(In,Ga)Se2, CIGS, Ga grading, Rear surface passivation, Al2O3, Atomic layer deposition, Point contact openings, Nano-sized
FunderEU, FP7, Seventh Framework Programme