Belgian researchers have developed perovskite solar panels with a thermally stable device stack. The encapsulated bifacial panels they created with this setup were able to retain about 92% of their original efficiency after 1,000 hours.
“We report the development of a stable device architecture that can be processed using industry-compatible techniques such as sputtering, evaporation, and gap coating,” said researcher Anurag Krishna. pv magazine.
The panel is based on 17% efficient perovskite solar cells constructed in a pin configuration, with an electron transport layer made of nickel(II) oxide (NiOx), a perovskite layer deposited with a slot-die coating, an electron transport layer made of buckminsterfullerene (C60) and lithium fluoride (LiF), a bathocuproine (BCP) buffer layer, and a copper (Cu) electrode.
The researchers constructed a 56-cell monofacial panel whose active area is 784 cm2, power conversion efficiency 13.08% and geometric fill factor (GFF) about 89%. They then built another bifacial module by replacing the Cu electrode with one based on indium tin oxide (ITO).
“Under heat and light stress, electrode metals such as Cu, Au, Ag, etc. are known to diffuse into the perovskite layer and thus compromise long-term stability, while the equipment with transparent conductive electrodes have shown much better stability under accelerated aging,” they explained. “ITO has a lower conductivity compared to metal electrodes, which can lead to resistance losses and thus a lower fill factor. To minimize this, we created a module structure with a smaller subcell width, resulting in 93 subcells. “
The bifacial panel has an opening area 781 cm2 and is able to achieve a power conversion efficiency of 11.9%.
“Furthermore, the developed encapsulated bifacial mini-modules (4 cm2) showed good tolerance to IEC 61215-based humid heat (85 C, 85% relative humidity (RH)), with the best ones retaining about 92% of their original efficiency after 1,000 hours,” Krishna said and pointed out that ipassivating the interface could further increase the efficiency of the device.
The researchers said the results show that the proposed device stack is thermally stable and that the encapsulation is durable enough to ensure stability.
The academics presented the module “Stable device architecture with industrially scalable processes for the implementation of efficient 784 cm2 Monolithic Perovskite Solar Modules”, published recently IEEE Journal of Photovoltaics.
“This work is an important milestone in the development of scalable fabrication techniques for perovskite photovoltaics,” Krishna said.