UCLA and Midsummer develop perovskite-CIGS tandem solar cells with 24.9% efficiency

University of California, Los Angeles (UCLA) researchers have joined forces with Swedish building-integrated PV (BIPV) module manufacturer, Midsummer, on a project that has yielded a four-terminal (4T) tandem solar cell based on a top cell made of perovskite and a bottom cell relying on copper, indium, gallium and selenium (CIGS).

The joint project between Midsummer and Prof. Yang's lab at UCLA resulted in a four-terminal perovskite-CIGS tandem solar cell, based on a commercial CIGS solar cell,  that reached 24.9 percent efficiency. The solar cell was based on a perovskite top cell that has been optimized for integration with Midsummer’s CIGS cells that are utilized in their commercial suite of BIPV products.


The device consists of a top layer of wide bandgap perovskite cell and a bottom layer of the CIGS cell. The research continues with the aim of a two-terminal perovskite-CIGS cell which will render this particular solar cell highly competitive and suitable for mass production.

This work shows the feasibility of building a tandem cell on a breakthrough production proven process developed at Midsummer and using the Midsummer DUO machine. The DUO production system developed by Midsummer is able to provide high performance CIGS solar cells with dimensions of 156 mm x 156 mm on a flexible stainless steel substrate. This form factor is ideally suited for subsequent processing of perovskite films on the company’s current BIPV product suite (SLIM; WAVE; and BOLD).

“We feel fortunate to be working with Professor Yang’s group at UCLA which has demonstrated key advances in perovskites,” said Leon Chiu, President, Pioneer Materials, Inc. which is a key supplier for compound sputtering targets used in Midsummer’s novel processing for CIGS on stainless steel. “Integrating Midsummer’s production proven CIGS processing with Yang’s Lab tailored perovskite shows a clear path toward expanding the reach of BIPV by improving efficiency and lowering costs.”

“Perovskite-CIGS tandem cells have great future potential and Midsummer’s solar panel design has by far the best conditions for building a commercial product for this type of solar panel, e.g since it contains a diode between each solar cell,” comments Sven Lindström, CEO, Midsummer.

Professor Yang Yang: “We are thrilled to have this opportunity to work with Midsummer and PMI. Our ultimate goal is to demonstrate two-terminal perovskite/CIGS tandem cells, suitable for mass production.”

Posted: Mar 20,2023 by Roni Peleg