Tag: solar cells

Making solar cells more weatherproof

Making solar cells more weatherproof

Dr. Tim Kelly calls it “the magic of science” – when what you think is going to happen doesn’t, but what you learn in the process promises to inform advances in a new type of solar cell. Solar cells, which convert sunlight into electricity, are increasingly being used to power everything from buildings and electric cars, to watches and toys.

In recent experiments at the Canadian Light Source (CLS) at the University of Saskatchewan (USask), Kelly, professor of chemistry at USask, and his team were trying to figure out why solar cells made with lead halide perovskite, rather than silicon, were failing prematurely. Perovskite, he explained, is a new semiconductor material that requires much less energy to produce than silicon, giving it an environmental advantage.

But it was a puzzle: “What makes them unstable? Why were these cells failing?”

Thinking the problem lay in the perovskite formulation, Kelly used a synchrotron technique called x-ray diffraction to visualize the 3D structure of the atoms in the material in real time.

In the experiments, Kelly and his team found cell performance started to decline with the introduction of humidity.

“We thought humidity would degrade the perovskite … because it does tend to pick up moisture more rapidly.” However, because they were able to watch – at a microscopic scale — the failure process as it unfolded, they could see that the moisture causes ions in the perovskite to become more mobile, to migrate to the electrode and to corrode it, “and now your device is no longer operative.”

“Like most of your electronics, it turns out getting these things wet is not a good idea.”

Kelly’s research identified possible solutions to address the issue of premature cell failure, including using corrosion-resistant materials for the electrodes, buffer layers to prevent the mobile ions from reaching the electrodes, or fully encapsulating the cell to keep out any moisture.

“There’s a lot of promise to the material (perovskite),” said Kelly, so solving the moisture issue could lead to high-performing and reliable solar cells.

The CLS was key to solving the cell-failure question, he said.

Read more on CLS website

Improvement of Efficiency and Stability of Lead-Free Perovskite Solar Cells

Improvement of Efficiency and Stability of Lead-Free Perovskite Solar Cells

Research Background and Objectives

Organic-inorganic halide perovskite solar cells have significant potential in solar energy development because of their long diffusion length, high light absorption coefficient, and excellent charge mobility. Due to these characteristics, the power conversion efficiency (PCE) of perovskite solar cells has rapidly increased from 3.8% to 26%. However, using lead (Pb) poses environmental and health risks, limiting commercialization. Therefore, active studies are being conducted on lead-free perovskite materials that maintain high efficiency while using less harmful substances.  

Alternative materials such as tin (Sn), germanium (Ge), antimony (Sb), bismuth (Bi), and copper (Cu) have been proposed. Among them, tin is considered a promising candidate to replace lead due to its high charge mobility, low exciton binding energy, and suitable bandgap. However, tin-based perovskites suffer instability and low efficiency (below 15%) caused by oxidation and strong self-doping. This study aims to improve structural stability and PCE by introducing additives to overcome these limitations. 

Experimental Methods and Procedures

In this study, we introduced various additives to improve the performance of tin-based perovskite solar cells, aiming to enhance grain growth and charge carrier mobility. The additives used in the experiment were bromides and various organic amine compounds, which were added to the precursor solution in small amounts. These additives were selected to help the vertical orientation of tin-based perovskite films and to increase grain size for charge recombination reduction and conductivity enhancement.  

Solar cell thin films were fabricated through spin coating and annealing, and solvent evaporation and crystallization were processed without anti-solvent treatment. Subsequently, we analyzed electrical characteristics to evaluate the efficiency and stability of the films with additive introduction and conducted the X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses in parallel to determine the crystal structure and defect states. 

Analysis Methods

To comprehensively analyze the effects of additives on tin-based perovskites, we applied synchrotron radiation analysis. In particular, small-angle X-ray scattering (SAXS) was used to investigate the effects of introducing additives on grain growth and structural orientation within the film. In addition, we observed the surface and cross-section of the film with an electron microscope to identify microstructural changes caused by introducing additives. Furthermore, to evaluate electrical characteristics, we measured open-circuit voltage (V_OC), short-circuit current density (J_SC), fill factor (FF), and PCE.  

Read more on PAL website

Breakthrough towards cheap and efficient solar cells

Breakthrough towards cheap and efficient solar cells

Scientists from EPFL and CSEM have made remarkable progress in the photovoltaics field, specifically in perovskite-on-silicon tandem solar cells, by achieving an impressive efficiency of 31.25%. This noteworthy accomplishment is a result of advancements in materials and processes that have successfully unlocked the true potential of this emerging technology. Studies at NCD-SWEET beamline of ALBA have been carried out to analyse these materials. The scientific breakthrough behind this milestone has been published in Science, representing a significant step towards a greener, cleaner energy future and the ongoing energy transition.

Cerdanyola del Vallès, 4th October 2023 Silicon solar cells that are commonly used for solar electricity generation are limited in terms of efficiency — the amount of sunlight that hits a solar cell and gets converted into electricity. The current highest efficiency records for silicon-only solar cells stand around 24.5% for commercial cells and 27% in laboratory settings. These figures are considered close to the theoretical maximum of 29% for such cells, with little progress in moving this number higher in recent years. Research groups worldwide are engaged in efforts to enhance the efficiency and develop innovative materials, like metal halide perovskites, as potential alternatives to silicon.

Racing past crucial energy barrier

To overcome this efficiency limitation and further reduce the costs of solar electricity, scientists from EPFL’s PV-Lab and CSEM have been exploring innovative approaches and finally demonstrated, in the article published in Science,an efficiency of 31.25% by stacking silicon and perovskite cells in a so-called tandem structure. This achievement marks the first time a low-cost technology has surpassed the 30% efficiency milestone.

Tandem solar cells offer improved utilization of solar energy by optimizing each sub-cell to capture different parts of the solar spectrum. However, a typical limitation of perovskite-on-silicon tandem cells is the recombination losses that occur at the perovskite interface with the electron selective contact. Recombination refers to the loss of photogenerated charge carriers before they can be collected and utilized to generate electricity.

To address this issue, EPFL’s and CSEM’s scientists started with a standard commercial silicon cell and incorporated an additive in the processing sequence when growing the perovskite crystal on top. This additive effectively regulated the perovskite crystallization process and passivated the perovskite top interface. Passivation involves adapting the structure and chemistry of interfaces and surfaces so that energy loss is minimized, and a maximum of the energy generated can be utilized efficiently.

A bright light for a brighter energy future

In order to deeply analyse the impact of the additive on the perovskite crystallization process, grazing incidence wide-angle x-ray scattering (GIWAXS) was performed at the ALBA Synchrotron. “GIWAXS provides detailed information about the crystallographic structure, orientation, and phase transitions within the material”, explains Eduardo Solano, beamline scientist at ALBA. In particular, Solano gives support to research groups who come to ALBA for using this synchrotron light-based technique at NCD-SWEET, a flexible dynamic multipurpose beamline that can accommodate a large variety of sample environments for in situ experiments.

Read more on ALBA website

Image: From left to right, Julian Steele, scientist at KU Leuven and at the University of Queensland, and Eduardo Solano, beamline scientist at NCD-SWEET.

Molecular movie of gold nanoparticle oscillations driven by displaced electrons

Molecular movie of gold nanoparticle oscillations driven by displaced electrons

Photocatalysis, sensors, solar cells: Plasmons promise a variety of applications if the processes triggered by optical excitation in the nanoparticles can be controlled. A research team from Hamburg and Berlin reports experimental observations of a so-called molecular movie that cannot be explained by established models in Nano Letters. The team including researchers from DESY provides a new theoretical model that explains the dynamics of excited gold nanoparticles observed in their experiments.

Plasmons are collective electron oscillations associated with highly localised fields. The decay of these oscillations after optical excitation is currently the subject of intense debate. Researchers assume that very energetic “hot” electrons are generated in the process which lose their energy by electron-electron scattering into a “warm” electron gas. The gas heats up the particle which eventually releases the excess energy into the environment. The efficiency of the energy transfer between the “hot electron”, “warm electron”, and “warm particle” stages is important for applications wanting to make use of these processes. In particular, the energy transfer from the warm electron gas to the nanoparticle appears to be so efficient that the particle is heated extremely quickly. In the process, it expands explosively, causing it to oscillate collectively, like a breathing sphere. However, so far direct experimental studies resolving the breathing oscillation have been missing.

For their study, researchers from the Departments of Physics and Chemistry at Universität Hamburg, the Max Planck Institute for the Structure and Dynamics of Matter (MPSD), the CFEL at DESY, and TU Berlin joined forces. Led by Holger Lange, Jochen Küpper, and Kartik Ayyer, who all conduct research in the Cluster of Excellence “CUI: Advanced Imaging of Matter”, and Andreas Knorr from Berlin, the team combined theory and experiment for an accurate description of the dynamics of excited gold nanoparticles.

Using single-particle X-ray diffractive imaging (SPI), performed at DESY’s FLASH facility, and transient absorption spectroscopy (TA), the researchers determined both the structural size and the electron temperature of the nanoparticles after optical excitation as a function of time. They observed that the particles already expanded with the optical excitation pulse, much faster than previously assumed. This observation directly proved the need for an immediate excitation source other than the temperature rise and associated expansion of the particle.

Read more on the DESY website

Image: Optical excitation of gold nanoparticles directly sets the particle into an oscillatory motion in which the particle periodically expands and contracts.

Credit: Univ. Hamburg/H. Lange

Extending the longevity of perovskite solar cells for cheaper solar energy

Extending the longevity of perovskite solar cells for cheaper solar energy

Study reveals the secret to treating the ‘Achilles’ heel’ of alternatives to silicon solar panels for the photovoltaics industry

Diamond’s Nanoprobe beamline I14 and the electron Physical Science Imaging Centre (ePSIC) were used by a multidisciplinary team of researchers to gain new insight into the perovskite materials that hold so much potential in the field of optoelectronics. Focusing on structural changes that can lead to degradation, the Diamond instruments were part of a suite that enabled the group to observe the nanoscale properties of thin films of perovskite materials and how they change over time under solar illumination. The research, recently published in Nature, could significantly accelerate the development of long-lasting, commercially available perovskite photovoltaics.  

Perovskite materials offer a cheaper alternative to silicon for producing solar cells and also show great potential for other optoelectronic applications, such as energy efficient LEDs and X-ray detectors.

The metal halide salts are abundant and much cheaper to process than crystalline silicon. They can be prepared in a liquid ink that is simply printed to produce a thin film of the material.

While the overall energy output of perovskite solar cells can often meet or – in the case of multi-layered, so-called ‘tandem’ devices – exceed that achievable with traditional silicon photovoltaics, the limited longevity of the devices is a key barrier to their commercial viability.

A typical silicon solar panel, like those you might see on the roof of a house, typically lasts about 20-25 years without significant performance losses.

Because perovskite devices are much cheaper to produce, they may not need to have as long a lifetime as their silicon counterparts at least to enter some markets – but to fulfil their ultimate potential in realising widespread decarbonisation, cells will need to operate for at least a decade or more. Researchers and manufacturers have yet to develop a device with similar stability to silicon cells.

Now, researchers at the Department of Chemical Engineering and Biotechnology (CEB) and Cavendish Laboratory at the University of Cambridge, together with the Okinawa Institute of Science and Technology (OIST) in Japan, have discovered that the defects that limit perovskite efficiency are also responsible for structural changes in the material that lead to degradation.

Read more on the Diamond website

Image: A typical silicon solar panel, like those you might see on the roof of a house, typically lasts about 20-25 years without significant performance losses

New angle for perovskite research

New angle for perovskite research

Perovskite materials offer the potential for cheaper optoelectronic devices such as solar cells. Of these, the formamidinium (FA)-based FAPbI3 crystal is one of the most promising – it has a bandgap close to ideal and is very thermally stable. However, photoactive cubic (α)-FAPbI3 perovskite phase is highly unstable and quickly transforms into the non-perovskite yellow phase at room temperature in ambient atmosphere, which affects the performance of photovoltaic devices. Alloying of FA-based perovskite with caesium, methylammonium (MA) cations or a combination of both can keep the perovskite in its more efficient phase at lower temperatures. However, this can give patchy results, leading to power losses.

In work recently published in Science, researchers from the University of Cambridge Department of Chemical Engineering and Biotechnology (CEB) and the Cavendish Laboratory investigated the crystal structure of the alloyed perovskite materials to understand why adding cations improved their performance. Their results show that cation alloying induces a minor octahedral tilt that keeps the perovskite material in its highly efficient phase, and is a step towards commercial production of stable and efficient perovskite-based solar cells. 

A small distortion makes a big difference

Formamidinium (FA)-based perovskites have much better thermal stability than the methylammonium (MA)-based absorber layers commonly used in early perovskite-based solar cells. FAPbI3 is a particularly promising material, but its photoactive phase is only stable at high temperatures (above 150ºC) in inert atmosphere. It transitions to a hexagonal phase with poor optoelectronic performance at lower temperatures.  

It has been shown empirically that alloying FAPbI3 with methylammonium (MA) cations or caesium (or both) improves stability. However, although this approach led to record efficiencies, the mechanism underlying it was not fully understood. It also produces uneven materials with patches of instability that lead to performance losses. 

Co-lead author Tiarnan Doherty was a PhD student at the Cavendish Laboratory and is now an Oppenheimer Fellow in CEB. He says:

We wanted to investigate the atomic structure of the alloyed perovskite materials, but they’re very sensitive to damage. So we brought the samples to ePSIC for high-resolution electron microscopy with a low electron dose. We also used nano X-ray diffraction on beamline I14. That beamline has very sensitive detectors, which allowed us to achieve our results using low X-ray exposures.

Read more on the Diamond website

Image: Artist’s impression of formamidinium (FA)-based crystal

Credit: Tiarnan Doherty, University of Cambridge

Advancing materials science with the help of biology and a dash of dish soap

Advancing materials science with the help of biology and a dash of dish soap

High-speed X-ray free-electron lasers have unlocked the crystal structures of small molecules relevant to chemistry and materials science, proving a new method that could advance semiconductor and solar cell development.

Compounds that form tiny crystals hold secrets that could advance renewable energy generation and semiconductor development. Revealing the arrangement of their atoms has already allowed for breakthroughs in materials science and solar cells. However, existing techniques for determining these structures can damage sensitive microcrystals.

Now scientists have a new tool in their tool belts: a system for investigating microcrystals by the thousands with ultrafast pulses from an X-ray free-electron laser (XFEL), which can collect structural information before damage sets in. This approach, developed over the past decade to study proteins and other large biological molecules at the Department of Energy’s SLAC National Accelerator Laboratory, has now been applied for the first time to small molecules that are of interest to chemistry and materials science.

Researchers from the University of Connecticut, SLAC, DOE’s Lawrence Berkeley National Laboratory and other institutions developed the new process, called small molecule serial femtosecond X-ray crystallography or smSFX, to determine the structures of three compounds that form microcrystal powders, including two that were previously unknown. The experiments took place at SLAC’s Linac Coherent Light Source (LCLS) XFEL and the SACLA XFEL in Japan.

Read more on the SLAC website

Image: Artist’s rendition of the X-ray beam illuminating a solution of powdered metal-organic materials called chalcogenolates.

Credit: Ella Maru Studios

Great minds think alike!

Great minds think alike!

Marion Flatken from BESSY II & Luisa Napolitano from Elettra give advice to those at the start of their careers

Our #LightSourceSelfies campaign features staff and users from 25 light sources across the world. We invited them all to answer a specific set of questions so we could share their insights and advice via this video campaign. Today’s montage features Marion Flatken from BESSY II, in Germany, and Luisa Napolitano from Elettra, in Italy. Both scientists offered the same advice to those starting out on their scientific journeys: “Be curious and stay curious”. Light source experiments can be very challenging and the tough days can lead to demotivation and self-doubts. In these times, it is good to seek out support from colleagues, all of whom will have experienced days like this. Even if you think you can’t succeed with your research goals, try because it is amazing what can be achieved through hard work, tenacity and collaboration.

World changing science

World changing science

Marion Flatken is a 3rd year PhD student working in the Department Novel Materials and Interfaces for photovoltaic solar cells led by Prof. Dr. Antonio Abate, at HZB.

In her #LightSourceSelfie, Marion describes the perovskite solar cell research she is undertaking and reflects on the opportunity light sources present to scientists.  She says,

“We are really having the chance to work in a unique environment and to use the knowledge and the facilities and the resources that we have to really change the world literally.”

Marion Flatken’s #LightSourceSelfie

Beamline filming location: HZB ASAXS-Instrument, FCM-beamline at PTB laboratory (Physikalisch-Technische Bundesanstalt), BESSYII

Sharper insights into thin-film systems

Sharper insights into thin-film systems

Interfaces in semiconductor components or solar cells play a crucial role for functionality. Nevertheless, until now it has often been difficult to investigate adjacent thin films separately using spectroscopic methods. An HZB team at BESSY II has combined two different spectroscopic methods and used a model system to demonstrate how well they can be distinguished.

Photoelectron spectroscopy (PES) enables the chemical analysis of surfaces and semiconductor layers. In this process, an X-ray pulse (photons) hits the sample and excites electrons to leave the sample. With special detectors, it is then possible to measure the direction and binding energy of these electrons and thus obtain information about electronic structures and the chemical environment of the atoms in the material. However, if the binding energies are close to each other in adjacent layers, then it is hardly possible to distinguish these layers from each other with PES.

 A team at HZB has now shown how precise assignments can nevertheless be achieved: they combined photoelectron spectroscopy with a second spectroscopic method: Auger electron spectroscopy. Here, photoelectrons and Auger electrons are measured simultaneously, which gives the resulting method its name: APECS for Auger electron photoelectron coincidence spectroscopy (APECS). 

Read more on the HZB website

Image: The illustration shows how the APECS measurement works on a nickel single crystal with an oxidised surface. An X-ray beam ionises atoms, either in the nickel crystal or on the surface. The excited photoelectrons from the surface and from the crystal have slightly different binding energies. The Auger electrons make it possible to determine the origin of the photoelectrons. 

Credit: © Martin Künsting /HZB

Perovskite Solar Cells: Insights into early stages of structure formation

Perovskite Solar Cells: Insights into early stages of structure formation

Using small-angle scattering at the PTB X-ray beamline of BESSY II, an HZB team was able to experimentally investigate the colloidal chemistry of perovskite precursor solutions used for solar cell production. The results contribute to the targeted and systematic optimization of the manufacturing process and quality of these exciting semiconductor materials.

Halide perovskite semiconductors are inexpensive, versatile, and high-performance materials used in solar cells as well as optoelectronic devices. The crystalline perovskite thin films required for this purpose are prepared at low temperature from solution: While the solvent evaporates during an annealing step, highly coordinated iodoplumbates interact and subsequently form the polycrystalline thin film. The quality of the thin film ultimately determines the performance of the semiconductor material. Up to now, it has not been possible to achieve a comprehensive impression of the role of the colloidal chemistry in the precursor that is considered to be directional for crystallinity and the further processing.

Read more on the HZB website

Image: Using Small-Angle Scattering the early stages of structure formation in precursor solutions of perovskite solar cells have been explored.

Credit: Image: © M. Flatken/HZB

First detailed look at how charge transfer distorts a molecule’s structure

First detailed look at how charge transfer distorts a molecule’s structure

Charge transfer is highly important in most areas of chemistry, including photosynthesis and other processes in living things. A SLAC X-ray laser study reveals how it works in a molecule whose lopsided response to light has puzzled scientists for nearly a decade.

When light hits certain molecules, it dislodges electrons that then move from one location to another, creating areas of positive and negative charge. This “charge transfer” is highly important in many areas of chemistry, in biological processes like photosynthesis and in technologies like semiconductor devices and solar cells.

Even though theories have been developed to explain and predict how charge transfer works, they have been validated only indirectly because of the difficulty of observing how a molecule’s structure responds to charge movements with the required atomic resolution and on the required ultrafast time scales.

In a new study, a research team led by scientists from Brown University, the Department of Energy’s SLAC National Accelerator Laboratory and the University of Edinburgh used SLAC’s X-ray free-electron laser to make the first direct observations of molecular structures associated with charge transfer in gas molecules hit with light.

Molecules of this gas, called N,N′-dimethylpiperazine or DMP, are normally symmetric, with a nitrogen atom at each end. Light can knock an electron out of a nitrogen atom, leaving a positively charged ion known as a “charge center.”

Read more on the SLAC website

Image: In experiments with SLAC’s X-ray free-electron laser, scientists knocked electrons out of a molecule known as DMP to make the first detailed observations of how a process called charge transfer affects its molecular structure. Left: DMP is normally symmetric. Center: When a pulse of light knocks an electron out of one of its nitrogen atoms (blue spheres), it leaves a positively charged ion known as a charge center, shown in pink. This creates a charge imbalance that shifts the positions of atoms. Right: But within three trillionths of a second, the charge redistributes itself between the two nitrogen atoms until it evens out and the molecule becomes symmetric again.

Credit: Greg Stewart/ SLAC National Accelerator Laboratory

A properly tailored tail boosts solar-cell efficiency

A properly tailored tail boosts solar-cell efficiency

With the help of structural insights from the Advanced Light Source (ALS), researchers optimized the fit between organic and inorganic ions in a perovskite solar-cell material.

The work increased the material’s power-conversion efficiency and stability and opens up a new avenue for improving the current-carrier dynamics of a promising class of materials.

A photovoltaic rising star

To address the effects of global climate change, it’s essential that we capitalize on energy from the sun. However, although solar energy is freely available, it needs to be converted into usable electricity in a way that’s efficient, cost-effective, and commercially scalable.

Perovskites are high-performance inorganic semiconductors recognized as some of the most promising photovoltaic materials of the future. Perovskite films—thin, lightweight, and flexible—can be produced using low-cost solution-processing techniques, and their power-conversion efficiencies (PCEs) have rapidly risen to the brink of 30% in just 15 years, surpassing conventional silicon panels.

A structure with room to tinker

The most intriguing perovskite materials today are organic–inorganic hybrids. They have the general formula ABX3, in which the inorganic B and X ions form a framework of octahedral cages, and the organic A ions are located in the spaces between the cages.

Previously, it was thought that perovskite electronic performance mainly depended on the B and X electronic orbitals, and that A merely served a structural function. In this work, researchers showed that A-site organic ions with specially designed characteristics can increase charge-carrier mobility and power conversion efficiency while also improving device stability.

Read more on the ALS website

Image: Left: The basic structure of perovskite, a promising solar-cell material, has three types of sites, A (blue), B (gray), and X (purple). Right: By attaching organic tails to the interstitial “A” sites (and testing different linker lengths), researchers improved the material’s photovoltaic response.

Tiny Chip-Based Device Performs Ultrafast Manipulation of X-Rays

Tiny Chip-Based Device Performs Ultrafast Manipulation of X-Rays

Researchers from the U.S. Department of Energy’s Advanced Photon Source (APS) and Center for Nanoscale Materials at Argonne National Laboratory have developed and demonstrated new x-ray optics that can be used to harness extremely fast pulses in a package that is significantly smaller and lighter than conventional devices used to manipulate x-rays. The new optics are based on microscopic chip-based devices known as microelectromechanical systems (MEMS).

“Our new ultrafast optics-on-a-chip is poised to enable x-ray research and applications that could have a broad impact on understanding fast-evolving chemical, material and biological processes,” said research team leader Jin Wang from the X-ray Science Division Time Resolved Research (TRR) Group at the APS. “This could aid in the development of more efficient solar cells and batteries, advanced computer storage materials and devices, and more effective drugs for fighting diseases.”

In new results published in The Optical Society OSA) journal Optics Express, the researchers demonstrated their new x-ray optics-on-a-chip device (Fig. 1), which measures about 250 micrometers and weighs just 3 micrograms, using the TRR Group’s 7-ID-C x-ray beamline at the APS. The tiny device performed 100 to 1,000 times faster than conventional x-ray optics, which that tend to be bulky.

Read more on the APS website

Image: Fig. 1. The photograph shows two MEMS elements on a single chip (A), with the active elements of 250 µm × 250 µm, and the micrograph (B) highlighting the size of the diffractive element, as compared to a section of human hair (C).

Perfect recipe for efficient perovskite solar cells

Perfect recipe for efficient perovskite solar cells

A long-cherished dream of materials researchers is a solar cell that converts sunlight into electrical energy as efficiently as silicon, but that can be easily and inexpensively fabricated from abundant materials. Scientists at the Helmholtz-Zentrum Berlin have now come a step closer to achieving this. They have improved a process for vertically depositing a solution made from an inexpensive perovskite solute onto a moving substrate below. Not only have they discovered the crucial role played by one of the solvents used, but they have also taken a closer look at the aging and storage properties of the solution.

Solar cells made of crystalline silicon still account for the lion’s share of roof installations and solar farms. But other technologies have long since become established as well – such as those that convert sunlight into electrical energy through use of extremely thin layers of solar-cell material deposited upon a substrate. The perovskite solar cells that Prof. Eva Unger and her team at the Helmholtz-Zentrum Berlin (HZB) are researching belong to this group. “These are the best solar cells to date that can be made using a 2D ink”, the researcher explains. “And now their efficiencies are approaching those for cells made of crystalline silicon.”

Read more on the HZB website

Image: The liquid solution of perovskite precursor, solvent, and additive flows from a slit-shaped nozzle onto the glass substrate being conveyed below.

Credit: © Jinzhao Li / HZB

Towards industrial-scale manufacturing of perovskite solar cells

Towards industrial-scale manufacturing of perovskite solar cells

For the production of high-quality metal-halide perovskite thin-films for large area photovoltaic modules often optimized inks are used which contain a mixture of solvents. An HZB team at BESSY II has now analysed the crystallisation processes within such mixtures. A model has also been developed to assess the kinetics of the crystallisation processes for different solvent mixtures. The results are of high importance for the further development of perovskite inks for industrial-scale deposition processes of these semiconductors.

Hybrid organic perovskite semiconductors are a class of materials for solar cells, which promise high efficiencies at low costs. They can be processed from precursor solutions that upon evaporation on a substrate form a polycrystalline thin film. Simple manufacturing processes, such as spin coating a precursor solution, often only lead to good results on a laboratory scale, i.e. for very small samples.

Read more on the HZB website

Image: Schematic illustration: the solvants (ink) are used to produce a thin film of polycrystalline perovskite. 

Credit: © HZB