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Category: solar power – Page 17

A research effort led by scientists at the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) has made advances that could enable a broader range of currently unimagined optoelectronic devices.

The researchers, whose previous innovation included incorporating a perovskite layer that allowed the creation of a new type of polarized (LED) that emits spin-controlled photons at room temperature without the use of magnetic fields or ferromagnetic contacts, now have gone a step further by integrating a III-V semiconductor optoelectronic structure with a chiral halide perovskite semiconductor.

That is, they transformed an existing commercialized LED into one that also controls the spin of electrons. The results provide a pathway toward transforming modern optoelectronics, a field that relies on the control of light and encompasses LEDs, solar cells, and telecommunications lasers, among other devices.

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Luminescence refers to the result of a process in which an object absorbs light at one wavelength and then re-emits it at another wavelength. Through light absorption, electrons in the ground state of the material are excited to a higher energy state. After a certain amount of time characteristic of each excited state, the electrons decay to lower energy states, including the ground state, and emit light. The phenomenon is used in a wide array of technological applications involving highly efficient and reproducible emitting devices that can easily be miniaturized.

The materials with the highest luminescence efficiency include (QDs), currently used in high-resolution displays, LEDs, solar panels, and sensors of various kinds, such as those used for precision medical imaging. Functionalization of the surface of QDs with various types of molecules permits interaction with cellular structures or other molecules of interest for the purpose of investigating molecular-level biological processes.

QDs are semiconductor nanoparticles whose emissive characteristics are directly linked to dot size, owing to the phenomenon of quantum confinement. For this reason, monitoring and control of crystal growth during synthesis of QDs in solution permits intelligent planning of the desired luminescence.

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A theoretical model for the illumination of photosynthesizing algae in giant clams suggests principles for high efficiency collection of sunlight.

Crops on a farm capture only about 3% of the available solar energy, much less than the 20%–25% captured by large solar arrays. Now a research team has used a theoretical model to explain efficiencies as high as 67% for photosynthesizing algae hosted by giant clams [1]. The researchers argue that clams achieve this performance with an optimized geometry. The mollusks may also adjust the algae clusters’ spacing according to changing light conditions. The researchers hope that an understanding of clams’ solar efficiency might help other scientists improve the efficiency of solar technology and explain aspects of the photosynthetic behavior of other ecosystems such as forests.

A photosynthetic cell can convert nearly every incoming photon to usable energy, says biophysicist Alison Sweeney of Yale University. But efficiency is much lower in larger systems such as agricultural fields. “Can we achieve near-perfect efficiencies over large land areas? This is an urgent question” as researchers try to reduce reliance on fossil fuels, Sweeney says.

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In a world first, a team of scientists has successfully developed the first flexible perovskite/silicon tandem solar cell with a record efficiency of 22.8 percent.

While other scientists have developed flexible solar cells before, the new efficiency record sets a new precedent and represents a big step forward for the technology.

It shows that flexible perovskite/silicon tandem solar cells are feasible, meaning they could soon be used for a large variety of applications.

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A new study highlights the successful development of the first flexible perovskite/silicon tandem solar cell with a record efficiency of 22.8%, representing a major advance in flexible solar cell technology.

Although rigid perovskite/silicon tandem solar cells have seen impressive advancements, achieving efficiencies as high as 33.9%, the development of flexible versions of these cells has been limited. The main hurdle is improving light absorption in the ultrathin silicon bottom cells without compromising their mechanical flexibility.

In their pioneering study, a research team led by Dr. Xinlong Wang, Dr. Jingming Zheng, Dr. Zhiqin Ying, Prof. Xi Yang, and Prof. Jichun Ye from the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, has successfully demonstrated the first flexible perovskite/silicon tandem solar cell based on ultrathin silicon, with a thickness of approximately 30 µm. By reducing wafer thicknesses and adjusting the feature sizes of light-trapping textures, they significantly improved the flexibility of the silicon substrate without compromising light utilization. Additionally, by capping the perovskite top cells, they enhanced the mechanical durability of the device, thus addressing concerns related to fractures in the silicon surface.

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A joint research team has unveiled a new topological insulator (TI), a unique state of matter that differs from conventional metals, insulators, and semiconductors. Unlike most known TIs, which are either three-or two-dimensional, this TI is one-dimensional. The breakthrough will lead to further developments of qubits and highly efficient solar cells.

Details of the research were published in the journal Nature (“Observation of edge states derived from topological helix chains”).

TIs boast an interior that behaves as an electrical insulator, meaning electrons cannot easily move; Whereas its surface acts as an electrical conductor, with the electrons able to move along the surface.

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