Stability - Page 19

Researchers at Nankai University in China have developed a Dion-Jacobson (DJ) two-dimensional perovskite solar cell. They claim it exhibits a power conversion efficiency of 18.82%, as well as remarkable light, thermal, environmental, and operational stability.

Two-dimensional (2D) Dion-Jacobson (DJ) phase perovskites have sparked interest in the scientific community due to their stability against harsh environmental conditions and their competitive performance in optoelectronic applications. Solar cells based on DJ perovskites, however, tend to show comparatively poor performance compared to their 3D counterparts.

Researchers at the National Renewable Energy Laboratory (NREL), along with collaborators from the SLAC National Accelerator Laboratory, University of Toledo, Princeton University, University of Arizona, University of Kentucky, and University of Colorado, have found away to improve the efficiency of perovskite solar cells by as much as 16%.

The effort involved combining a two-dimensional (2D) perovskite layer with a three-dimensional (3D) perovskite layer, which yielded a solar cell with improvements in both efficiency and stability.

Researchers from Rice University and collaborators from Purdue and Northwestern universities, U.S. Department of Energy national laboratories Los Alamos, Argonne and Brookhaven and the Institute of Electronics and Digital Technologies (INSA) in Rennes, France, have reached a new benchmark in the design of atomically thin solar cells made of semiconducting perovskites, boosting their efficiency while also focusing on their stability.

The lab of Aditya Mohite of Rice's George R. Brown School of Engineering discovered that sunlight itself contracts the space between atomic layers in 2D perovskites enough to improve the material's photovoltaic efficiency by up to 18%.

Researchers from various universities and laboratories around the world have recently melted metal-organic frameworks (MOFs) and mixed them with perovskites to yield highly stable luminescent composites. The mixtures reportedly resist exposure to heat, air, and humidity.

Lead-halide perovskites, such as cesium lead iodide, naturally exhibit photoluminescence, says chemist Thomas D. Bennett of Cambridge University and the paper's lead author. 'However, this light-emitting phase is only stable at high temperatures, and its effects disappear when the material cools down,' he adds. In the new work, researchers preserved this photoluminescence using MOF glasses to trap this metastable phase at room temperature and, at the same time, encapsulate and protect the perovskite.

Scientists from Japan's Kishu Giken Kogyo and University of Hyogo, Switzerland's Solaronix and Germany's Fraunhofer ISE have examined the long-term stability of perovskite solar cells using layers of mesoporous carbon, building on previous work that showed the strong potential of this approach.

Schematics of reversible light-induced performance increase for m-CPSM. Image from study

This recent work demonstrated a light-soaking effect, which allowed them to fabricate cells that retained 92% of their initial performance after 3,000 hours in damp heat conditions – which the researchers say is equivalent to 20 years in the field.

In October 2021, The Perovskite-Info team met Cyprus University of Technology's (CUT) Professor Stelios Choulis, who kindly agreed to show us around his workspace and labs and update us on his team's ongoing work.

Choulis, Professor of Material Science and Engineering at the Cyprus University of Technology, is also the founder and head of the Molecular Electronics and Photonics (MEP) Research Unit. With work in UK, Germany and the Silicon Valley (USA) under his belt, Choulis is a highly skilled and experienced researcher in the fields of both photovoltaics and OLEDs. He also participated and led several large-scale research programs (ERC-Consolidator Grant European Horizon project, SME-EU FP7, RIF and RPF-Cyprus, BMBF-Germany, DOE-USA).

Researchers from University of North Carolina, North Carolina State University and Chinese Academy of Sciences have fabricated a mini perovskite solar module using a novel encapsulation technique based on the use of a self-healable, lead-adsorbing ionogel that prevents lead leakage and improves stability. The solar module has an area of 31.5cm² and has a reported efficiency of 22.9%.

Ionogel microstructure and lead adsorption mechanism. Image from article

The scientists explained that ionogel sealants were applied on the panel's front glass and between electrode and encapsulation glass, with the 100μm-thick inonogel being able to hold the shattered glass together even if the glass breaks. This is claimed to effectively suppress lead leakage from broken modules after hail test or compression by car wheels, and soaking in water for 45 days.

A research team at KTH Royal Institute of Technology has developed a synthetic alloy that increases perovskite cells' durability while preserving energy conversion performance.

'Perovskite usually dissolves immediately on contact with water,' says co-author James Gardner, a researcher at KTH. 'We have proven that our alloyed perovskite can survive for several minutes completely immersed in water, which is over a 100 times more stable than the perovskite alone. What's more, the solar cells that we have built from the material retain their efficiency for more than 100 days after they are manufactured.'

A research team from the Fraunhofer Institute for Solar Energy Systems, NREL, Solaronix SA and the Materials Research Center of the University of Freiburg has reported perovskite solar cells with carbon-based electrodes, which demonstrate impressive resilience against reverse-bias-induced degradation.

Previous studies have shown that a negative voltage applied to conventional perovskite solar cell stacks resulted in breakdown and irreversible destruction of the device. In this study, the international research team identified two main degradation mechanisms. The first is iodine loss due to hole tunneling into perovskite, which takes place even at low reverse-bias but decomposes the perovskite only after long time durations. Another factor is local heating at large reverse-bias leading to the formation of PbI₂, which starts at shunts and then follows the path of the least resistance for the cell current, which is primarily influenced by the electrode sheet resistance. The newly designed modules successfully endured the hotspot test conditions specified in IEC 61215-2:2016 international standard at an accredited module testing laboratory.

Researchers at the University of Rome Tor Vergata's Centre for Hybrid and Organic Solar Energy (CHOSE) and ISM-CNR have tested a commercially available HTM with a new core made by low-cost fluorene'xantene units. The experimentation was conducted on small (0.09 cm²) and large area (1.01 cm²) cells.

The one-pot synthesis of this compound is said to drastically reduce its cost compared with the commonly used Spiro-OMeTAD. The optoelectronic performances and properties were characterized through JV measurement, IPCE (incident photon to current efficiency), steady-state photoluminescence and ISOS stability test. SEM (scanning electron microscope) images reveal a uniform and pinhole free coverage of the X55 HTM surface, which reduces the charge recombination losses and improves the device performance relatively to Spiro-OMeTAD from 16% to 17%. The ISOS-D-1 stability test on large area cells without any encapsulation reports an efficiency drop of about 15% after 1000 h compared to 30% for the reference case.