Efficiency - Page 60

In a recent study, EPFL researchers demonstrated how light affects perovskite film formation in solar cells. The team showed that, in the two most common methods used today, light can greatly accelerate the formation of perovskite films and control the morphology of their crystals, influencing the efficiency of the resulting solar cell.

The team used confocal laser scanning fluorescence microscopy and scanning electron microscopy to examine how direct light affects the crystal formation when depositing perovskites in layers, a common stage in building a solar cell. The goal is to ensure homogeneity across the perovskite film, as this is linked to superior photovoltaic performance.

A team from Yale University has discovered a modification of perovskite that can increase the stability and efficiency of perovskite solar cells.

The team explained that light usually generates an exciton in most semiconductor materials, a state where an electron is bound to an electron hole via an electrostatic force. In order to produce usable electricity, the bound electron-hole pair has to be separated into a free electron and free electron hole. This is usually done by electron acceptors, which can overcome the binding energy holding the electron-hole pair together. However, since perovskite semiconductors possess exciton binding energies as low as 16 meV, they generally do not require the use of electron acceptors, which eases the process of generating electricity.

Researchers at The University of Toledo (UT) in the US have developed an all-perovskite tandem solar cell with excellent conversion efficiency. The new kind of device combines two different cells to harvest different parts of the solar spectrum, resulting in increased total electrical power generated.

The team's process enables the fabrication of bottom cells using mixed Sn-Pb perovskite absorbers. The fabrication of the efficient bottom cell, which the researchers say had not been accomplished before, is what is truly innovative about this research work. 'Our all-perovskite solar cells have the so-called four-terminal structure, which stacks a wide-band-gap top cell with a low-band-gap bottom cell. The current all-perovskite tandem cells are limited by the lack of efficient bottom cell'.

Imec, a leading research and innovation hub in nano electronics, energy and digital technologies, and partner in Solliance, announced that it has improved its 4x4cm² perovskite module achieving a certified conversion efficiency of 12.4%.

The module efficiency was measured under long-term maximum power point (MPP) tracking, testifying to its exceptional stability. At Solliance, this perovskite technology is developed with industrially-applicable processes and with a view towards a rapid market introduction of this promising source of renewable energy.

Researchers at Purdue University and the National Renewable Energy Laboratory have found that certain hybrid perovskites could double the amount of electricity produced without a significant cost increase. This could help in creating efficient solar cells thinner than conventional silicon solar cells, that are also flexible, cheap and easy to make.

The material, a crystalline structure that contains both inorganic materials (iodine and lead) and an organic material (methyl-ammonium), boosts the efficiency so that it can carry two-thirds of the energy from light without losing as much energy to heat.

Researchers at the Korea-based Ulsan Institute of Science and Technology (UNIST) have announced the development of a method to produce perovskite solar cells, demonstrating hybrid organic/inorganic perovskite solar cells of 21.2% efficiency, with good stability ' retaining 93% of the initial performance after 1,000 hours of light exposure.

The study, a collaboration between UNIST and the Korea Institute of Chemical Technology (KRICT), proposes a new manufacturing method for perovskites - the 'hot-pressing method'. The University says that this method allows the production of stable, low cost-high efficiency perovskite solar cells.

Researchers at the Australian National University (ANU) have reportedly achieved a new world record in the development of perovskite-based solar cells - 26% efficiency in converting sunlight into energy.

The ANU team has been experimenting with perovskite solar cells placed on top of silicon solar cells. The researchers say that the perovskite cells are much better than silicon ones at absorbing blue light, so it is possible to get a much higher voltage out of them. This can be used to circumvent silicon solar cells' efficiency limit, and the ANU team states that it is "... a step closer to a low-cost alternative".

Microquanta Semiconductor, a China-based thin-film PV firm, has announced a new efficiency record for perovskite mini-modules: 15.24%, certified by Newport PV Lab in Montana, US. The tested mini-module has an aperture size of more than 16 cm².

Microquanta said that by passing the 15% efficiency milestone for the first time, it has moved significantly closer towards commercialization of perovskite solar cells. It also claimed that perovskite mini-modules are desirable since they can reduce the manufacturing cost of current c-Si based solar cells by between 60-80%.

Researchers at Los Alamos National Laboratory and their partners are creating innovative 2D layered hybrid perovskites that they say can allow greater freedom in designing and fabricating efficient optoelectronic devices. Industrial and consumer applications could include low cost solar cells, LEDs, laser diodes, detectors, and other nano-optoelectronic devices.

They explain that these materials are layered compounds, or a stack of 2D layers of perovskites with nanometer thickness (like a stack of sheets), and the 2D perovskite layers are separated by thin organic layers. "This work could overturn conventional wisdom on the limitations of device designs based on layered perovskites", the team says.

Solliance, a partnership of R&D organizations from the Netherlands, Belgium and Germany working on thin film photovoltaic solar energy, recently demonstrated an industrially-applicable roll-to-roll process for the production of solar cells achieving a record 12.6% conversion efficiency on cell level. This result allows for an accelerated market introduction of this attractive new source of renewable energy.

The roll-to-roll (R2R) process was developed for both the electron transport and the perovskite layers on the new Solliance dual R2R coating line. The in-line roll-to-roll coating, drying, and annealing processes were executed at a linear speed of 5m/min on a 30-cm wide commercial PET/ITO foil and under ambient conditions. All process steps on this roll-to-roll line were performed using low-cost materials while keeping the process temperatures below 120 ⁰C, which is indicative of the production potential of this new emerging thin film PV technology.