Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 5: Photovoltaics: CIGS and related compounds

HL 5.2: Talk

Monday, March 16, 2015, 09:45–10:00, EW 202

Influence of metastable defect characteristics on the carrier collection in Cu(In,Ga)Se₂ thin film solar cells — •Stephan J. Heise¹, Maria S. Hammer¹, Viktor Gerliz¹, Jörg Ohland¹, Janet Neerken¹, Jan Keller², and Ingo Riedel¹ — ¹Energy and Semiconductor Research Laboratory, Chair: Jürgen Parisi, Department of Physics, University of Oldenburg — ²Currently: Department of Engineering Sciences, Solid State Electronics, Uppsala Universitet

Despite the current progress of Cu(In,Ga)Se₂ thin film photovoltaics, the relation between the metastable defect characteristics and key parameters of the solar cells has not yet been fully explained. In this work we discuss the correlation between metastable defect densities and short-circuit current J_SC of solar cells conditioned via white-light soaking (LS) and dark air-annealing (DA), respectively. The J_SC of DA-treated devices was found to decrease by 0.8 mAcm⁻² upon LS treatment, which suggests a conditioning-induced change of the carrier collection. Partly, this phenomenon can be attributed to a change of the metastable net doping density. However, device simulations and cross-section EBIC measurements suggest that this explanation is not sufficient to describe the observed J_SC difference. Moreover, time-resolved photoluminescence revealed a significant decrease of the decay lifetime upon LS along with an increase of the N1 defect concentration by 9.5·10¹⁴ cm⁻³, as evaluated from temperature dependent admittance spectra. In conclusion, we propose, that the observed J_SC metastability originates from both, treatment-induced changes of the net doping concentration and defect-related transport properties.