Light soaking effect on photocurrent collection in (Zn,Mg)O/Cu(In,Ga)Se₂ solar cells

Abstract

The metastable behaviour, so‐called light soaking (LS) effect, on (Zn,Mg)O (ZMO)/Cu(In,Ga)Se2 (CIGS) solar cells with controlled conduction band offset (CBO) values of the ZMO/CIGS layers was characterized. When the conduction band of ZMO is higher than that of CIGS, which creates the notch of the ZMO/CIGS interface in the conduction band, metastable current‐voltage curves were observed. The metastability becomes prominent with increasing the CBO value. Quantum efficiency measurements before and after the LS revealed that the LS effect was mainly originated by the metastability in the photocurrent collection which influenced by the notch acting as a barrier for photo‐generated electrons in the CIGS layer. The model for the LS effect is discussed with simulated energy band diagrams. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Hetero Junction Engineering for High Efficiency Cu(In,Ga)Se₂ Solar Cells

“…The hetero junction engineering by the CBO matching dominates both diode and photo currents, indicating that the CBO control is important to achieve high efficiency. Also, we pointed out that the CBO matching influenced photo J-V meta-stability so-called light soaking effect [11][12][13].…”