Efficiency - Page 43

A research group led by Prof. LIU Shengzhong from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has reported the fabrication of high efficiency large-area perovskite solar module using slot-die coating with high-pressure nitrogen-extraction (HPNE) and effective passivation strategy.

Slot-die coating is a promising deposition technique due to its advantages in low cost, high throughput, continuous roll-to-roll fabrication. However, it remains a challenge to control thin film uniformity over a large area at thickness as thin as 500 nm while maintaining crystallization quality.

A team of researchers, led by China's Nanjing University, have found that a chemical most commonly used in the textile industry can also serve as a performance-enhancing additive for mixed lead/tin perovskite thin films. They have used this additive to create a two perovskite tandem cell measuring 1.05cm² that achieved 24.2% efficiency.

Mixed lead-tin perovskites are known to have the right narrow bandgap for use as the top cell in a tandem device. However, despite similar theoretical efficiency potential, the development of these materials has stayed behind that of pure lead perovskites. One reason for this, according to scientists, is that the tin tends to oxidize during fabrication of the film, leading to high levels of defects and non-uniformity in the film. 'Defective grain surfaces are vulnerable to trap generation and Sn²⁺ oxidation,' state the group led by Nanjing University Professor Hairen Tan. 'And this works against the stability, efficiency, and scaling of mixed Pb'Sn perovskite solar cells and all-perovskite tandems.'

Researchers at the Department of Energy's Oak Ridge National Laboratory and the University of Tennessee, Knoxville, have led a study into perovskite solar cells that has revealed a way to slow phonons, the waves that transport heat.

The discovery has the potential to improve hot-carrier solar cells, which convert sunlight to electricity more efficiently than conventional solar cells by harnessing photogenerated charge carriers before they lose energy to heat.

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a new wide-bandgap perovskite layer – called Apex Flex – which they claim is able to withstand heat, light, and operational tests, and at the same time provide a reliable and high voltage.

With this material, they have built tandem solar cells with 23.1% power conversion efficiency on a rigid substrate, and 21.3% on flexible plastic. The new Apex Flex wide-bandgap perovskite recombination layer is grown with atomic layer deposition (ALD). The new material is described as a “nucleation layer consisting of an ultra-thin polymer with nucleophilic hydroxyl and amine functional groups for nucleating a conformal, low-conductivity aluminum zinc oxide layer.”

Scientists from City University of Hong Kong (CityU) recently developed a novel method which can simultaneously tackle both the lead leakage issue of perovskite solar cells and the stability issue without compromising efficiency, paving the way for real-life application of perovskite photovoltaic technology.

Perovskite solar cells tend to contain lead components, which raise concerns for potential environmental contamination. "As the solar cell ages, the lead species can leak through the devices, e.g. through rainwater into the soil, posing a toxicity threat to the environment," explained Professor Alex Jen Kwan-yue, CityU's Provost and Chair Professor of Chemistry and Materials Science. "To put PVSCs into large-scale commercial uses, it requires not only high power conversion efficiency but also long-term device stability and minimized environmental impact."

The Institute for Solar Energy Research Hamelin (ISFH), the Karlsruhe Institute of Technology (KIT) and the Institute for Materials and Components in Electronics at the University of Hannover, as well as Centrotherm, Singulus, Meyer Burger and Von Ardenne, are involved in a research project aimed at achieving 33%-efficient perovskite-silicon tandem solar cell suitable for mass production.

The new research project is called '27plus6′ and it brings together the expertise of leading German and Swiss technology companies and research institutes. The consortium said that it aims to achieve the promised conversion efficiency under standard test conditions, and that is also seeking to reach a higher power yield, intended to accelerate industrial implementation.

Australian Scientists from the University of New South Wales have outlined a new method for ensuring more of the sun's energy can be converted into electricity by using sunlight that would otherwise be wasted as heat.

In a photovoltaic solar cell, sunlight is converted into electricity through a process called the photoelectric effect, where individual packets of light, called photons, transfer their energy onto electrons within the solar cell material. If a sufficient amount of energy is transferred by light to an electron, an amount of energy known as the 'bandgap', the electron is knocked loose from its atom and creates an electric current. This is the process by which solar panels convert light into electricity.

Researchers from the Okinawa Institute of Science and Technology Graduate University (OIST) have created next-generation perovskite-based solar modules with high efficiency and good stability. These solar modules can reportedly maintain a high performance for over 2000 hours.

"There are three conditions that perovskites must meet: they must be cheap to produce, highly efficient and have a long lifespan," said Professor Yabing Qi, head of the OIST Energy Materials and Surface Sciences Unit, who led this study.

A team of researchers from MIT and Northwestern University has created hybrid perovskite materials that could help improve the quality of solar cells and light sources. They demonstrated the ability to fine-tune the electronic properties of these hybrid perovskite materials.

The materials are classified as 'hybrid' because they contain inorganic components like metals, as well as organic molecules with elements like carbon and nitrogen, organized into nanoscale layers. In the new paper, the researchers showed that by strategically varying the composition of the organic layers, they could tune the color of light absorbed by the perovskite and also the wavelength at which the material emitted light. Importantly, they accomplished this without substantially changing the inorganic component.

Researchers at the University of Sydney and University of New South Wales working with chemists at the University of Wisconsin-Madison in the United States have created a highly efficient and long-lasting solar-flow battery, which is a way to generate, store, and redeliver renewable electricity from the sun in one device.

The new device is made of perovskite-silicon tandem solar cells integrated with specially designed chemical battery components. The solar-flow battery achieved a new record efficiency of 20 percent conversion of energy from the sun. This is 40 percent more efficient than the previous record for solar-flow batteries, which were also developed in the University of Wisconsin Jin lab where lead author, PhD student Wenjie Li, is based.