Swiss scientists have built a 4T tandem perovskite/CIGS mini-panel with a geometric fill factor of over 93%. It combines a 10.8%-efficient mini perovskite module and a 15.1%-efficient CIGS device.

The 19.2%-efficient perovskite cells used in the module rely on an electron layer based on tin oxide that was deposited via chemical bath deposition. This technique, according to the device’s creators ...