In this work, the impacts of surface sulfurization of high‐quality Cu(In 1−x ,Ga x )Se 2 (CIGS) thin films deposited by three‐stage process on the film properties and the cell performance were investigated. The CIGS thin films were sulfurized at 550 °C for 30 min using H 2 S gas. The X‐ray photoelectron spectroscopy analysis revealed that sulfur atoms diffused into the CIGS surface layer and that the valence band minimum was lowered by the film sulfurization. The open circuit voltage ( V oc ) drastically increased from 0.590 to 0.674 V as a result of the sulfurization process. Temperature‐dependent current–voltage and capacitance–frequency measurements also revealed that interface recombination was drastically decreased by the lowering of the defect's activation energy level at the vicinity of the buffer/CIGS interface after the sulfurization. Copyright © 2014 John Wiley & Sons, Ltd. Temperature‐dependent current–voltage curves on Cu(In 1−x ,Ga x )Se 2 (CIGS) solar cells (a) without and (b) with surface sulfurization, respectively. The CIGS device (a) without surface sulfurization showed a J–V roll‐over at the temperature lower than 240 K. On the other hand, the sample (b) with surface sulfurization does not exhibit such a roll over in the J–V curves at temperature ranging from 300 to 140 K, indicating that this secondary diode effect was suppressed, due to the passivation of the surface defects by surface sulfurization.
Impacts of surface sulfurization on Cu(In1−x,Gax)Se2 thin‐film solar cells
Progress in photovoltaics ; 23 , 10
2015
Article (Journal)
English
BKL: | 53.36 Energiedirektumwandler, elektrische Energiespeicher |
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