Efficiency - Page 62

Researchers from the University of California, Berkeley, and Lawrence Berkeley National Laboratory have developed a flexible perovskite solar cell that reaches an efficiency of 21.7%, a peak conversion efficiency of 26% and could be manufactured using a low cost roll-to-roll process.

Many previous attempts to merge two perovskite materials have failed because the materials degrade one another's electronic performance. This design was achieved using a new way of combining two perovskite solar cell materials ' each tuned to absorb a different wavelength or color of sunlight ' into one 'graded bandgap' solar cell that absorbs nearly the entire spectrum of visible light.

Researchers at Stanford University and Oxford University have reportedly combined two perovskite materials to produce a stable solar cell with efficiency over 20% that can be printed on a plastic substrate. The teams have developed four and two-terminal perovskite-perovskite tandem solar cells with ideally matched bandgaps. Each cell is printed on glass, but the same technology could be used to print the cells on plastic.

They developed an infrared absorbing 1.2eV bandgap perovskite, FA0.75Cs0.25Sn0.5Pb0.5I3, that delivers 14.8% efficiency. By combining this material with a wider bandgap FA0.83Cs0.17Pb(I0.5Br0.5)3 material, a monolithic two terminal tandem cell provides efficiencies of 17.0% with over 1.65 V open-circuit voltage. The team has also mechanically stacked four terminal tandem cells and obtain 20.3% efficiency.

Scientists at Oxford University have developed a solvent system with reduced toxicity that can be used to manufacture perovskite solar cells, which may clear one of the barriers to the commercialization of a technology.

By combining methylamine and acetonitrile, researchers have developed a clean solvent with a low boiling point and low viscosity that quickly crystallises perovskite films at room temperature and could be used to help coat large solar panels with the material.

Researchers from the US National Renewable Energy Laboratory (NREL) have achieved 10.77% conversion efficiency with perovskite solar cells made from quantum dots with no organic components.

Solutions of all-inorganic perovskite quantum dots, showing intense photoluminescence when illuminated with UV light

The result was achieved with a thin film made of nanocrystals of cesium lead iodide (CsPbI3). The team discovered a method to keep the crystal structure in the all-inorganic perovskite material stable at room temperature, something that was previously possible only at temperatures exceeding 600 degrees Fahrenheit. The use of methyl acetate as an anti-solvent to remove excess unreacted precursors proved a crucial step in increasing the nanocrystals' stability.

A team of researchers from Italy has created hybrid perovskite-graphene solar cells that show good stability upon exposure to sunlight, while still maintaining an impressive efficiency of over 18% - the highest reported efficiency of graphene perovskite hybrid solar cells to date.

Despite tremendous progress in Perovskite PV performance, the stability of these devices is still questionable. In particular, air and humidity degrade cell performance, as do continued exposure to sunlight and heat, setting back the advantages over other types of solar cells. Graphene and graphene-related materials (GRMs) have properties that make them shine in applications like protective layers, andso arise as natural candidates to protect PSCs from atmospheric degradation.

Researchers from Karlsruhe Institute of Technology (KIT), ZSW and IMEC presented at the PSCO international conference a prototype of the new solar module using thin-film technology. According to the researchers, an efficiency of 17.8% has been achieved in this prototype of a perovskite/CIGS tandem thin-film solar module, exceeding the efficiency of individual perovskite and CIGS solar modules for the very first time.

To create the new solar module, the researchers used a stack module. By merging both perovskite and CIGS into one module, the new structure could benefit from the advantages of both technologies. The upper semitransparent layer of the model is made of perovskite, which absorbs high solar energy. Meanwhile, the lower CIGS layer is responsible for infrared conversion. Having an area of 3.67 square meters, the stacked perovskite/CIGS model is also designed to meet industrial needs. It features a monolithic interconnection scheme using 4 and 7 module cell stripes. Unlike other small-scale solar cells, the new stacked solar module can be interconnected for several square meters through laser processing.

Researchers at EPFL (École Polytechnique Fédérale de Lausanne) in Switzerland have stabilized perovskite solar cells by integrating metallic element rubidium into them, driving power-conversion efficiency to a staggering 22%.

The research outlines the integration of rubidium cations into perovskites; The perovskites maintained stability for more than 500 continuous hours in full sunlight at 85°C. The project team has already submitted a patent based on their innovation.

A team of scientists at Columbia University has discovered the possibility of greatly boosting the efficiency of hybrid organic inorganic perovskite (HOIP) solar cells.

The team showed how HOIPs have a far lower rate of energy loss than silicon cells, making it possible for the harvesting of excess electronic energy to increase the efficiency of solar cells. The recent Columbia study has actually found that it's possible to make HOIP-based solar cells even more efficient than anyone thought possible.

Researchers at Saudi Arabia's King Abdullah University of Science and Technology (KAUST) have shown how imploding bubbles in a solution can grow single crystals of perovskites especially suited for solar applications.

The researchers explain that hybrid perovskite materials can easily be fabricated on a large scale from a solvent solution. However, this process typically produces polycrystalline perovskite films that have a smaller solar light conversion efficiency than monocrystalline materials because the boundary between crystalline grains leads to losses. In particular, growth of single-crystalline perovskite solar cell films has not yet been achieved on top of other materials, which is a requirement for practical devices.

Researchers at the University of Groningen provided new insight into hybrid perovskite traps - the loss of electric charges that happens in both silicon and perovskite, and reduces the efficiency of photovoltaic cells.

The new insight happened by chance. The researchers placed a perovskite crystal in a vacuum chamber in an attempt to cool it down and while pumping out the air, a laser was left on, that excited the crystal. This laser light produced electronic charges in the crystal, which emitted light when they recombined. In this instance the crystal should have emitted green light, but surprisingly, when the air was removed from around it, the green light disappeared too. However, when the air was let back in again, the light emission was restored. So apparently, without air, most charges disappear into the traps.