‘World Record’ For CIGS-Perovskite Tandem Cell With 24.6% Efficiency

The German research center Helmholtz Zentrum Berlin (HZB) and Humboldt University Berlin have announced what they term as a new world record of 24.6% efficiency for a CIGS-perovskite tandem solar cell. 

This efficiency claim is certified independently by Germany’s Fraunhofer Institute for Solar Energy Systems. 

Its structure includes a thin-film Copper, Indium, Gallium and Selenium (CIGS) solar cell on the bottom of the tandem, while a perovskite cell is placed on the top. The perovskite cell on the top was fabricated by TU Berlin master's student Thede Mehlhop under the supervision of Stefan Gall, while the perovskite absorber layer was produced in the joint laboratory of HZB and Humboldt University. 

The CIGS sub-cell used at the bottom of this configuration, along with its contact layers, was fabricated by HZB researcher Guillermo Farias Basulto. He used the high-performance cluster system KOALA to deposit perovskites and contact layers in vacuum at HZB.  

HZB explains that the cell structure has a contact layer, followed by an intermediate layer of aluminum-doped zinc oxide, above which is a thin perovskite layer, followed by an indium-doped zinc oxide layer, and an anti-reflective coating.

With this configuration and improving the contact layers between the 2 cells, the researchers say they achieved this record high efficiency of 24.6%.  

This is an improvement over the 24.16% efficiency HZB announced in April 2020 for the same configuration (see 24.16% Efficiency Claim for CIGS-Perovskite Tandem Cell). 

Prof. Rutger Schlatmann, the Spokesman for the Solar Energy Department at HZB,  said, “We are confident that CIGS-perovskite tandem cells can achieve much higher efficiencies, probably more than 30%.”  

In March 2023, Midsummer and UCLA declared 24.9% efficiency for a 4-terminal CIGS-perovskite tandem cell (see 24.9% Perovskite-CIGS Tandem Solar Cell Efficiency).