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Flexible Cu(In,Ga)Se2 Solar Cells with Absorber Thickness of 1 µm Deposited at Higher Evaporation Rates
P. Reinhard, F. Pianezzi, B. Bissig, C.M. Fella, S. Nishiwaki, S. Buecheler, A.N. Tiwari
CIGS, Flexible, Thin Film (TF), Growth Rate
Subtopic: CdTe, CIS and Related Ternary and Quaternary Thin Film Solar Cells
Event: 28th European Photovoltaic Solar Energy Conference and Exhibition
Session: 3BV.5.58
2337 - 2340
ISBN: 3-936338-33-7
Paper DOI: 10.4229/28thEUPVSEC2013-3BV.5.58
0,00 EUR
Document(s): paper


Use of flexible substrates, growth of thinner absorbers or growth at higher deposition rates are suitable strategies to increase the manufacturing throughput of Cu(In,Ga)Se2-based photovoltaics. In this work these 3 aspects are combined and the influence of increased growth rate for thinner absorbers (0.8-0.9 μm) deposited on flexible polyimide foils is investigated. Our low temperature multi-stage co-evaporation process is modified to grow CIGS absorber layers with about 1/3 of the standard thickness leading to a total deposition time of 20 min. Evaporation rates are increased separately (up to 4 times the standard rate) in each stage while they are kept constant in the other stages. The microstructure is not affected significantly by the increase in growth rate during any stage. No decrease in performance is observed with increased deposition rate in the 1st and 3rd stage. Improved photovoltaic parameters are measured for the cell with the absorber grown at a higher rate during the 2nd stage, leading to an increase in conversion efficiency from 13.7% up to 15.1% compared to an absorber grown with standard evaporation rates. Modifications of the absorber microstructure and electronic quality are discussed to explain the differences in final solar cell performance.