Publication Date:
2015-02-04
Description:
Solar cells based on Cu(In 1− x , Ga x )Se 2 typically show time transient behavior of the open-circuit voltage V oc under illumination. In this work, we study both the red-light V oc ( t ) transient and the red-light capacitance transient at different temperatures of samples with different x. From the capacitance transient, we calculate a transient behavior of the Cu(In 1− x ,Ga x )Se 2 doping density N A , a ( t ). Then, using established models on the N A , a dependence of the dominant recombination mechanisms, we derive from V oc ( t ) that Cu(In 1− x ,Ga x )Se 2 samples with x = 0, 0.3 are dominated by bulk recombination and a sample with x = 1 is dominated by interface recombination—in agreement with the expectation. Further, the transients of N A , a ( t ) can be used to recalculate V oc ( t ) transients which are then compared with the measured V oc ( t ) transients. From the excellent agreement, we conclude that under red-light illumination V oc ( t ) indeed is dominated by N A , a ( t ) and other transient effects are of secondary importance. We further conclude that the sample with x = 1 can be described by an absorber/buffer/window energy band diagram with fully depleted buffer layer which here is CdS.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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