CIGS solar cell with IBC structure and up to 19.7% efficiency

• Researchers in the Netherlands have actually shown an interdigitated back call copper-indium-gallium-selenide solar cell with a sub-micron thickness of 673nm. The device has a light weight aluminum oxide as well as magnesium fluoride-based anti-reflective coating.

Scientists at Delft University of Technology in the Netherlands have actually established an interdigitated back get in touch with (IBC), copper-indium-gallium-selenide (CIGS) solar cell with a sub-micron thickness of 673nm.

The Delft researchers stated standard, front/back call (FBC) solar cells endure optical losses as a result of parasitic absorption by their top layers which can trigger a 10% loss in photocurrent density. On top of that, the researchers mentioned, "When it comes to flexible CIGS solar cells, the metal grid triggers an added optical shading, minimizing a lot more the optical efficiency."

The IBC cell designed by the Delft team was compared with an 11.9%- effective FBC tool supplied by Dutch institute Solliance Solar Research, with the Delft team concentrating specifically on absorber efficiency.

The Delft cell included a double-layer anti-reflective covering based on light weight aluminum oxide (Al2O3) and magnesium fluoride (MgF2). "The ideal thicknesses of Al2O3 and MgF2 for this job are 80 and also 85nm, specifically," claimed the Delft group. "The Al2O3 layer at the front side of the absorber serves likewise as [a] chemical and also electric passivation layer."

Reflector

The scientists positioned a reflector on the back side of their device to raise the chance of secondary absorption of photons.

A gallium‐doped zinc‐oxide (GZO) was made use of as an n‐doped clear conductive oxide on the IBC cell. That compound is stated to have high doping focus, low absorption coefficient, high thermal security as well as low free-carrier absorption.

With simulations between both solar cells performed by varying geometrical criteria as well as absorber material features, the Delft tool revealed 17% efficiency. "Since the high quality of our simulated absorber, from [a] defect-density perspective, is lower than the state‐of‐the‐art CIGS absorber product, we researched the effect of issue thickness on the cell efficiency," the researchers mentioned. "We observed that by reducing the mass problem density from 5 × 1013cm − 3 to 1 × 1013cm − 3, the performance can be boosted to 19.7%.".

The researchers stated the visibility of unfavorable fixed charges in the Al2O3 layer ensured electric passivation and also reduced recombination at little gap-width values. "We demonstrated how an IBC structure with optimal bandgap grading and high absorber top quality can help us achieve high performances with sub-micron CIGS layers," stated the Delft group.

Commercialization.

While accepting the pricey patterning steps called for to replicate the gadget could prove a difficulty to commercialization of their innovation, the Delft group stated their design could be particularly suitable for 3 and also four‐terminal tandem solar devices.

The Delft solar cell is described in Interdigitated back‐contacted structure: A various technique in the direction of high‐efficiency ultrathin copper indium gallium (di) selenide solar cells, released in Progess in Photovoltaics.

Researchers from the Helmholtz-Zentrum Berlin (HZB) in April announced they had attained 24.16% efficiency with a tandem cell which incorporated CIGS and also perovskite innovation. That turning point took tandem gadget performance past the 23.35% record for a standalone 1cm ² CIGS cell which was set by Solar Frontier in January in 2019.