Hybrids and related materials - Page 4

Researchers from Helmholtz-Zentrum Berlin (HZB), Eindhoven University of Technology and Technical University Berlin have combined rear junction silicon heterojunction bottom cells with p'i'n perovskite top cells into highly efficient monolithic tandem solar cells with a power conversion efficiency (PCE) of 26.0%.

Colored cross sectional SEM image of the top cell (upper panel) and back side of the bottom cell (lower panel) of a typical monolithic tandem solar cell used in this work. (b) schematic device layout of the tandem architecture utilized in this work.

Starting from a certified efficiency of 25.0%, further improvements have been reached by reducing the current mismatch of the certified device. The top contact and perovskite thickness optimization allowed increasing the JSC above 19.5 mA cm'2, enabling a remarkable tandem PCE of 26.0%, however with a slightly limited fill factor (FF).

Researchers at the University of Toronto have designed a method of growing a more stable electron selective layer for perovskite solar cells and tandem solar cells combining crystalline silicon with perovskite.

Perovskite raw materials can be mixed into a liquid in a kind of 'solar ink.' This solar ink could be printed onto glass, plastic or other materials with a relatively simple inkjet printing process. However, in order to generate electricity, electrons excited by solar energy from perovskite cells must be extracted from a layer of quantum dots that is held together by a passivation layer. Some types of quantum dots are known to change their 3D structure even at room temperature, making them transparent and ineffective. This passivation layer is also known to break down at temperatures above 100°C. The team's breakthrough made both quantum dots and perovskites more stable when combined than they are separated and the solar cell combining of Perovskite material and quantum dots achieved 20.1% efficiency.

Researchers at the National Renewable Energy Laboratory (NREL) report the creation of an efficient tandem perovskite solar cell, using a new chemical formula which also improved the structural and optoelectronic properties of the solar cell.

Most of the research efforts in the field of PSCs have focused on lead-based perovskites, which have a wide bandgap. High efficiency, low bandgap perovskites would enable the fabrication of very high efficiency all-perovskite tandem solar cells where each layer absorbs only a part of the solar spectrum and is optimally configured to convert this light into electrical energy. However, low bandgap perovskites have long suffered from large energy losses and instability limiting their use in tandems.

Researchers at the Energy Research Center of the Netherlands (ECN) have developed a bifacial tandem solar cell with a conversion efficiency of 30.2%. The new cell device ' created with Dutch consortium Solliance ' was made by applying a newly developed perovskite cell on top of an industrial bifacial crystalline silicon version.

This approach, according to the scientists, enables a significantly higher power conversion efficiency as one cell is optimized for high energy photons, and the other low energy particles. 'The tandem device proposed here uses a four-terminal configuration, thus having separate circuits for the top and bottom cells that allow for dynamic fine tuning and optimization of the energy yield,' the creators of the cell wrote. The cell is also said to be better able to capture light on its front and rear sides by responding to the variability of incident light through its electronic design.

Researchers from HZB, Oxford University, Technical University Berlin and Oxford PV have shown that the infrared reflection losses in tandem cells processed on a flat silicon substrate (such as perovskite/silicon tandem cells) can be significantly reduced by using an optical interlayer, consisting of nanocrystalline silicon oxide. Based on this, the team managed to achieve impressive efficiency and reported that the best tandem device in this work reached a certified conversion efficiency of 25.2%.

a) Cross-section of the simulated monolithic perovskite/SHJ tandem cell (layer thicknesses and morphological features not to scale). b) Cross-sectional SEM image of the top region of the tandem device.

Perovskite/silicon tandem solar cells are attractive for their potential for boosting cell efficiency beyond the crystalline silicon (Si) single-junction limit. However, the relatively large optical refractive index of Si, in comparison to that of transparent conducting oxides and perovskite absorber layers, often results in significant reflection losses at the internal junction between the cells in monolithic (two-terminal) devices. Therefore, light management is crucial for improving photocurrent absorption in the Si bottom cell.

Researchers at the Germany-based Helmholtz Center Berlin (HZB) have announced a thin-film solar cell made of perovskite and copper-indium-gallium-selenide (CIGS) with an efficiency of 21.6%.

The HZB researchers said they used a simple, robust production process suitable for scaling up. Rutger Schlatmann, director of the HZB's Institute PVcomB, spoke of an 'enormous step in the direction of commercial production'. The HZB team's tandem cell could theoretically reach an efficiency of more than 30%, according to the researchers.

Researchers at Solliance, in collaboration with MiaSole Hi-Tech Corp., have designed a flexible solar cell with an impressive power conversion efficiency of 21.5%. The solar cell combines two thin-film solar cell technologies into a 4 terminal tandem solar cell stack: a top flexible semi-transparent perovskite solar cell with a bottom flexible copper indium gallium selenide (CIGS) cell.

A tandem solar cell, which combines a perovskite and a Cu(In,Ga)Se2 (CIGS) cell, has the potential for high conversion efficiency exceeding single junction solar cell performance thanks to tunable and complementary bandgaps of these individual thin film solar cells. CIGS technology has a proven track record as a high efficiency and stable solar technology, and has entered high volume manufacturing in multi-GW scale around the world. CIGS technology has been successfully used to produce high efficiency flexible and lightweight cells and modules, which address markets where heavy and rigid panels cannot be used. Perovskite solar cells, promise low cost solar technology based on abundant materials. Combining both technologies in a flexible and lightweight package expands the horizon of high performance, flexible, and customizable solar technology.

Oxford PV, a leading developer of perovskite solar cells, has announced a new, certified, 28% efficiency world record for its perovskite-based solar cell.

Oxford PV's 1 cm² perovskite-silicon tandem solar cell has achieved a 28% conversion efficiency, certified by the National Renewable Energy Laboratory. The achievement trumps Oxford PV's previous certified record of 27.3% efficiency for its perovskite-silicon solar cell, announced earlier this year.

Researchers from the Australian National University (ANU), in collaboration with researchers from and the California Institute of Technology, have developed a way to combine silicon with perovskites to achieve higher efficiencies and lower production costs. They believe that this could lead to cheaper and more efficient solar technology.

The new way to create crystalline silicon and perovskite tandem PV cells is claimed by the team to be the simplest method of doing so.

Researchers from Arizona State University have achieved 25.4% efficiency in their tandem solar cell stacked with perovskite and silicon. This follows, and surpasses, last year's achievement of 23.6% efficiency.

The team's improvement upon the record by nearly two percentage points was reached in a joint project with researchers at the University of Nebraska'Lincoln, predicting they'll be nearing 30% tandem efficiency within two years.