How does cigs solar cell work

Effects of material and process choices NREL scientists have been key in helping industry understand how cost-effective, industrially relevant process choices can impact the ultimate performance and reliability of CIGS modules.

NREL is pursuing new materials for inclusion into the cell structure that will meet these requirements. We can fabricate novel materials and device structures and also perform advanced characterization and device modeling.

The absorber the CIGS layer in a solar cell is where the action is. Here, the light is absorbed and, through the photovoltaic effect, an electron-hole pair is created. The objective is to collect that electron before it runs into something and is re-absorbed called recombination.

This collection of electrons becomes the electricity we use to light a light bulb. It turns out electrons want to recombine in the bulk CIGS material itself as well as at interfaces with other materials.

The perfect solar material would be optimized to maximize generation of electrons in the bulk material, but minimize recombination in the bulk as well as at each of the interfaces. If one were lucky, a single material would be perfect for all of these jobs. So far though, no one has encountered this perfect material. With silicon, the mainstay of solar technology, the bulk properties are altered at both the top and bottom contact to maximize efficiency.

It turns out CIGS can do that too, but only in the three-stage co-evaporation process. The stages in the co-evaporation process can be thought of as zones of deposition. If multiple stages are employed, the materials properties can be adjusted throughout its thickness; the more zones, the more process control. Therefore, a three-stage co-evaporation can be optimized for good absorption with minimal recombination in the bulk, but with different material properties at the top and bottom contact to minimize recombination at these interfaces.

It is no surprise that the world records for efficiency over the last 10 or more years are all accomplished with three-stage co-evaporation.

It is clear that three-stage co-evaporation is preferred, but it is also true that this process takes the most skill to implement. The processing tool is more complicated than a simple sputtering or nanoparticle printing system, but avoiding this process leads to sub-optimal results.

There is just no better way to do it. The last decision when implementing a CIGS process is the architecture of the device and the manufacturing process flow. Choices are:. For example, the cylindrical substrate used at Solyndra doomed the technology from the beginning. Here you can see some of the differences on CIGS and crystalline solar cells. Cookies and privacy We use cookies for statistical analysis, marketing and to improve the friendliness and usability of our website.

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A major increase in device performance was achieved when the ceramic or borosilicate glass substrate was replaced by soda-lime glass. Although soda-lime glass was chosen because it has closer thermal expansion properties to CIGS, it was ultimately determined that the primary advantage of using soda-lime glass results from the diffusion of sodium Na ions from the glass into the CIGS absorber layer.

Current manufacturing techniques incorporate Na either from soda-lime glass or a separate Na source. Soda-lime glass has an added advantage of being less expensive than previous glass substrates.