Northwestern University Achieves Milestone: Inverted Perovskite Solar Cell Shatters 25% Efficiency Record with Innovative Molecular Approach

Northwestern University researchers have propelled perovskite solar cells to new efficiency records with a groundbreaking development that addresses losses during the conversion of sunlight to energy. The study, published in the journal Science on November 17, introduces a dual-molecule solution to enhance efficiency. The first molecule tackles surface recombination, a process where electrons are lost due to defects on the surface. The second molecule disrupts recombination at the interface between layers. This innovative approach resulted in a certified efficiency of 25.1%, surpassing previous methods that achieved 24.09%.

Perovskite solar technology is evolving rapidly, and the focus of research is shifting towards improving interfaces rather than the bulk absorber, according to Northwestern professor Ted Sargent, co-executive director of the Paula M. Trienens Institute for Sustainability and Energy. The team’s achievement represents a crucial advancement in efficiency and stability, propelling perovskite solar cells closer to becoming a more efficient solar harvesting method.

Conventional solar cells, typically made of high-purity silicon wafers, have limitations in terms of energy-intensive production and fixed absorption ranges in the solar spectrum. Perovskite materials offer a promising alternative with adjustable size and composition, allowing for the tuning of absorbed light wavelengths. This adaptability positions perovskite solar cells as a potentially cost-effective and high-efficiency tandem technology.

While perovskite solar cells historically faced challenges due to their relative instability, recent breakthroughs from Sargent’s lab and others have brought their efficiency within the range achievable with silicon. In this latest research, the emphasis shifted from increasing sunlight absorption to addressing the critical issue of retaining generated electrons for increased efficiency.

When the perovskite layer connects with the electron transport layer, electrons move between them. However, the risk of electrons moving back outward and recombining with holes on the perovskite layer has historically posed a challenge. The dual-molecule solution introduced in this study effectively mitigates these issues, marking a significant stride forward in the quest for more efficient and stable perovskite solar cells.