The influence of atmospheric species on the degradation of the Mo/MoSe2 back contact in CIGS solar cells

The degradation mechanisms of the molybdenum (Mo) back contact for Cu(In,Ga)Se2 solar cells in the presence of atmospheric species have been investigated. Mo/MoSe2 films on glass were immersed in water purged with the gases oxygen (O2), nitrogen (N2), carbon dioxide (CO2), air, in non-purged water, and exposed to air. It was found that the...

Interdigitated back-contacted structure: A different approach towards high-efficiency ultrathin copper indium gallium (di) selenide solar cells

An interdigitated back-contacted (IBC) configuration is proposed for submicron copper indium gallium (di)selenide (CIGS). In a modelling platform, the structure was opto-electrically optimized for maximum efficiency. The results are compared with a reference front/back-contacted (FBC) solar cell with similar absorber thickness and exhibiting 11...

Optical study of back-contacted CIGS solar cells

A novel back-contacted solar cell based on a submicron copper indium gallium (di)selenide (CIGS) absorber is proposed and optically investigated. First, charge carrier collection feasibility is studied by band diagram analysis. Then, two back-contacted configurations are suggested and optimized for maximum current production. The results are...

An optical study of back contacted CIGS solar cells

An optical investigation of ultra-thin CIGS solar cells and guidelines for elimination of optical losses is presented. Then, a novel back contacted structure for CIGS solar cells is suggested and optimized for best implied photocurrent density.

Damp heat related degradation mechanisms within CIGS solar cells

Degradation rates and mechanisms for molybdenum back contacts and ZnO:Al front contacts exposed to damp heat were obtained from literature and experiments. It was found that molybdenum back contacts with a higher density and covered by a MoSe2 film are more stable than their low density, bare counterparts. For ZnO:Al front contacts various...

Stability of CIGS solar cells under illumination with damp heat and dry heat: A comparison

Unencapsulated CIGS solar cells were simultaneously exposed to either dry or damp heat combined illumination. In-situ monitoring of their electrical parameters demonstrated a rapid decrease of the efficiency for the solar cells exposed to damp heat plus illumination. This decrease was mainly driven by changes in the shunt resistances, affecting...

Determination of the temperature dependency of the electrical parameters of CIGS solar cells

Two types of Cu(In,Ga)Se2 (CIGS) solar cells, both designed for implementation in CIGS modules, were subjected to temperatures between 25C and 105C. Simultaneous exposure to AM1.5 illumination allowed the measurement of their electrical parameters at these temperatures. These two types of solar cells, produced with different deposition routes on...

Spatial Atomic Layer Deposition of Zn(O,S) buffer layers for CIGS solar cells

Damp-heat-induced degradation of layers in CIGS solar cells

Investors require a guarantee of a minimum lifetime for PV installations. It is tempting to provide such a guarantee for a longer lifetime simply by specifying test conditions that are more and more severe. In this paper it is argued that, with a more detailed understanding of the basic mechanisms determining cell material behaviour under...

The impact of alkali elements on the degradation of CIGS solar cells

Unencapsulated CIGS solar cells with high and low contents of sodium (Na) and potassium (K) were simultaneously exposed to damp heat and illumination. The solar cells with a high alkali (Na, K) content exhibited higher initial conversion efficiencies, but degraded severely within 100-h, while the alkali poor samples kept relatively stable...

The impact of atmospheric species on the degradation of CIGS solar cells and molybdenum films

CIGS solar cells and non-covered molybdenum areas and scribes were exposed to liquid water purged with the atmospheric gases carbon dioxide (CO2), oxygen (O2), nitrogen (N2) and air in order to investigate their degradation behavior. The samples were analyzed by electrical, compositional and optical measurements before, during and after exposure...

The impact of atmospheric species on the degradation of CIGS solar cells

CIGS solar cells were exposed to liquid water purged with the atmospheric gases carbon dioxide (CO<inf>2</inf>), oxygen (O<inf>2</inf>), nitrogen (N<inf>2</inf>) and air in order to investigate their chemical degradation behavior. The samples were analyzed by electrical, compositional and optical measurements before, during and after exposure in...

Reliability testing solar cells and modules

Degradation of CIGS solar cells

Large scale commercial introduction of CIGS photovoltaics (PV) requires modules with low costs, high efficiencies and long and predictable lifetimes. Unfortunately,knowledge about the lifetime of CIGS PV is limited, which is reflected in the results of field studies: degradation rates varying from 0% to about 4% per year have been observed....

A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers

We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the CIGS layer does not decrease monotonically with...

Influence of deposition pressure and selenisation on damp heat degradation of the Cu(In,Ga)Se2 back contact molybdenum

The impact of the molybdenum (Mo) microstructure and selenisation on degradation caused by 105hour exposure to standard 'damp heat' has been investigated. Degradation effects were already observed without magnification after several hours of exposure. The degradation resulted in large volume expansion due to the formation of a thick non...

Identifying parasitic current pathways in CIGS solar cells by modelling dark JV response

The presence of undetermined shunt pathways in CIGS solar cells can be severely limiting to the reproducibility of individual cell efficiency, both at lab-scale, and particularly in a roll-to-roll process. Here, a general model that describes the dark J-V characteristics of CIGS devices, accounting for three separate shunting pathways (Ohmic and...

The influence of atmospheric species on the degradation of aluminum doped zinc oxide and Cu(In,Ga)Se2 solar cells

Aluminum doped zinc oxide (ZnO:Al) layers were exposed to the atmospheric gases carbondioxide (CO2), oxygen (O2), nitrogen (N2) and air as well as liquid H2O purged with these gases, in order to investigate the chemical degradation behavior of these layers. The samples were analyzed by electrical, compositional and optical measurements before,...