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El-Hajje G.,Electricite de France | El-Hajje G.,Chimie Paristech | El-Hajje G.,Institute Photovoltaique Dile Of France | Ory D.,Electricite de France | And 10 more authors.
Solar Energy Materials and Solar Cells | Year: 2016

The authors present a contactless optical characterization method for the study of metastable defects in Cu(In,Ga)Se2 solar cells. A methodology for the analysis of time-resolved photoluminescence (TRPL) signals is presented. It leads to the observation of a hysteresis phenomenon regarding the minority carrier dynamics following the activation of the metastable defects. The amplitude of the hysteresis phenomena was compared between CIGS solar cells with different absorber/buffer layer interface properties. It is in these particular spatial regions where the metastable defects can be mostly found. The developed contactless characterization method was compared with classical current-voltage measurements. TRPL leads to a more complete understanding of the physics of metastable defects in terms of quantifying the shift in minority charge carriers dynamics that it induces. © 2015 Elsevier B.V. Source


El-Hajje G.,Electricite de France | El-Hajje G.,Chimie Paristech | El-Hajje G.,Institute Photovoltaique Dile Of France | Ory D.,Electricite de France | And 8 more authors.
Applied Physics Letters | Year: 2016

In this letter, we investigate the origin of the spatial inhomogeneity of the photoluminescence (PL) intensity maps obtained on thin-film solar cells. Based on a hyperspectral imager setup, we record an absolute map of the quasi-Fermi level splitting Δμ by applying the generalized Planck's law. Then, using scanning confocal microscopy, we perform spatially and time-resolved photoluminescence measurements. This allowed us to quantify and map the micrometric fluctuations of the trapping defect density within these solar cells. Finally, we demonstrate the existence of a direct correlation between the spatial fluctuations of the quasi-Fermi level splitting and the trapping defect density. The latter was found to be correlated with the frequently reported spatially inhomogeneous PL maps of thin-film solar cells. Based on the observed correlation, we can quantify the local losses in quasi-Fermi level splitting induced by the spatial distribution of the trapping defects. © 2016 Author(s). Source

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