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HL: Fachverband Halbleiterphysik

HL 5: Photovoltaics: CIGS and related compounds

HL 5.3: Vortrag

Montag, 16. März 2015, 10:00–10:15, EW 202

Kinetics of phase separation and coarsening in Cu-In-Ga precursor thin films for sequentially processed Cu(In,Ga)Se₂ solar cells — •Jan-Peter Bäcker¹, Humberto Rodriguez-Alvarez¹, Manuel Hartig³, Christian A. Kaufmann¹, Jaison Kavalakkatt², Roland Mainz², Saoussen Merdes¹, Sebastian S. Schmidt¹, Christian Wolf¹, Florian Ziem¹, and Rutger Schlatmann¹ — ¹PVcomB, Helmholtz-Zentrum Berlin, Germany — ²Helmholtz-Zentrum Berlin, Germany — ³Technische Universität Berlin, Germany

Obtaining smooth and homogenous Cu(In,Ga)Se₂ films by fast selinzation of metallic precursors is a major challenge. Separation and coarsening of metallic phases in Cu-In-Ga precursor films can lead to solar cells with low shunt resistance due to pinhole formation, and to reduced open circuit voltages due to locally varying Ga concentration. In this study we attempt to establish a general model for the kinetics of the phase separation and coarsening of sputtered Cu-Ga-In metallic films as used for Cu(In,Ga)Se₂ fabrication. For this we measure the roughness with atomic force microscopy and the Ga spatial distribution by energy dispersive X-ray spectroscopy. We study four different metallic precursor stacks heated to 170^∘C, 350^∘C and 580^∘C, at rates between 0.01K/s and 1K/s. Finally, we present a statistical analysis of the effect of our optimized multilayered precursors on the fill factor of the solar cells prepared in our atmospheric-pressure in-line and fast selenization baseline, that has led to power conversion efficiencies of up to 15.5% (active area).