Degradation Mechanism Due to Water Ingress Effect on the Top Contact of Cu(In,Ga)Se2 Solar Cells

Deewakar Poudel,Sushma Swaraj Atluri,Sina Soltanmohammad,Shankar Karki,Benjamin Belfore,Grace Rajan,Angus Rockett,Sylvain Marsillac

doi:10.3390/en13174545

Deewakar Poudel, Sushma Swaraj Atluri + Show 6 more

Open Access

https://doi.org/10.3390/en13174545

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Journal: Energies	Publication Date: Sep 2, 2020
Citations: 17	License type: CC BY 4.0

Affiliation: Old Dominion University, Colorado School of Mines

Abstract

The impact of moisture ingress on the surface of copper indium gallium diselenide (CIGS) solar cells was studied. While industry-scale modules are encapsulated in specialized polymers and glass, over time, the glass can break and the encapsulant can degrade. During such conditions, water can potentially degrade the interior layers and decrease performance. The first layer the water will come in contact with is the transparent conductive oxide (TCO) layer. To simulate the impact of this moisture ingress, complete devices were immersed in deionized water. To identify the potential sources of degradation, a common window layer for CIGS devices—a bilayer of intrinsic zinc oxide (i-ZnO) and conductive indium tin oxide (ITO)—was deposited. The thin films were then analyzed both pre and post water soaking. To determine the extent of ingress, dynamic secondary ion mass spectroscopy (SIMS) was performed on completed devices to analyze impurity diffusion (predominantly sodium and potassium) in the devices. The results were compared to device measurements, and indicated a degradation of device efficiency (mostly fill factor, contrary to previous studies), potentially due to a modification of the alkali profile.

Highlights

Many studies have been performed to evaluate the effect of damp heat treatment on copper indium gallium diselenide (CIGS) solar cells as a whole [1,2,3], but the discrete layers are rarely analyzed [4,5].the study of water-induced degradation, comparable to corrosion, is rarely studied.In previous publications, we have analyzed the impact of water on both CIGS and molybdenum components of CIGS devices [6,7]
We have analyzed the impact of water on both CIGS and molybdenum components of CIGS devices [6,7]
Spectra did not show any noticeable change in peak position, peak position, peak intensity, preferential orientation, or broadening, before and after water soaking peak preferential broadening, andnot after water soakingthat in the in theintensity, symmetric geometryorientation, X-ray diffraction (XRD) (θ\2θ)orpatterns

Summary

Introduction

Many studies have been performed to evaluate the effect of damp heat treatment on copper indium gallium diselenide (CIGS) solar cells as a whole [1,2,3], but the discrete layers are rarely analyzed [4,5]. Direct moisture exposure studies have not been performed In this V study, we modified the deposition parameters of the ITO and characterized full CIGS solar voltage, OC [15]. This is one of the primary degradation mechanisms observed in accelerated lifetime. CIGS films were deposited using a three-stage layer was formed at high argon pressure and the top layer at low pressure, resulting in a co-evaporation process [16], as rapidly as possible by formation a CdSa layer using cochemical tensile/compressive stress followed dipole. 1.5 GG with lightintensity intensityofof mW/cm with aa light mW/cm °C

Effect of Water Ingress on the Window Layer

Effect

Representative semi-log plots of the dark

10. Detailed

Conclusions