Introduction of Si PERC Rear Contacting Designto Boost Efﬁciency of Cu(In,Ga)Se2 Solar Cells
2014 (English)In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 4, no 6, 1644-1649 p.Article in journal (Refereed) Published
Recently, Cu(In,Ga)Se-2 (CIGS) solar cells have achieved 21% world-record efficiency, partly due to the introduction of a postdeposition potassium treatment to improve the front interface of CIGS absorber layers. However, as high-efficiency CIGS solar cells essentially require long diffusion lengths, the highly recombinative rear of these devices also deserves attention. In this paper, an Al2O3 rear surface passivation layer with nanosized local point contacts is studied to reduce recombination at the standard Mo/CIGS rear interface. First, passivation layers with well-controlled grids of nanosized point openings are established by use of electron beam lithography. Next, rear-passivated CIGS solar cells with 240-nm-thick absorber layers are fabricated as study devices. These cells show an increase in open-circuit voltage (+57 mV), short-circuit current (+3.8 mA/cm(2)), and fill factor [9.5% (abs.)], compared with corresponding unpassivated reference cells, mainly due to improvements in rear surface passivation and rear internal reflection. Finally, solar cell capacitance simulator (SCAPS) modeling is used to calculate the effect of reduced back contact recombination on high-efficiency solar cells with standard absorber layer thickness. The modeling shows that up to 50-mV increase in open-circuit voltage is anticipated.
Place, publisher, year, edition, pages
2014. Vol. 4, no 6, 1644-1649 p.
Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:uu:diva-235498DOI: 10.1109/JPHOTOV.2014.2350696ISI: 000344542900049OAI: oai:DiVA.org:uu-235498DiVA: diva2:760900