One of the major challenges in the world today is the energy crisis. The high demand and low supply of fossil fuel are driving up oil and food prices. Silicon-based solar cells are one of the most promising technologies for generating clean and renewable energy.
Using these devices to convert just a fraction of the sunlight that hits the earth each day into electricity could drastically cut society’s dependence on fossil fuels. Unfortunately, however, high-grade silicon crystals demand great care during the manufacturing process, making the resulting high production cost one of the main obstacles in the road to commercialization.
One way to bring down the production cost of these solar cells is to deposit layers of silicon onto cheaper substrates such as plastic or glass. However, this approach has one drawback: silicon thin films have lower power conversion efficiencies than bulk silicon crystals because they absorb less light and contain more defects. Patrick Lo at the A*STAR Institute of Microelectronics and co-workers have now discovered an approach for increasing the power conversion efficiency of silicon thin films deposited on cheap substrates.
Low-grade silicon thin films suffer from one inherent problem: they cannot absorb photons whose wavelengths are larger than their film thickness. For instance, a standard, 800-nm-thick thin film may capture short-wavelength blue light, but will completely miss longer-wavelength red light. “To keep material costs low and improve light efficiency, the trick is to trap more photons, including those with medium wavelengths,” says Lo.
One way to trap more photons in the silicon thin film is to carve tiny silicon pillars—hundreds of nanometers in size—in the silicon surface (see image). Lo explains that the silicon nanopillars are like a forest of trees, in which light enters and cannot easily get out. “When light strikes the surface, it bounces a few more times along or inside the pillars before penetrating the bottom flat surface,” he says. “Each bouncing event increases the chances of photon absorption.”
Lo and co-workers used computer simulations to determine the best configuration for extracting electrical charges from the defect-ridden silicon films. They found that the upper portion of each pillar can be made extremely conductive by introducing large amounts of dopants. Lo and co-workers are now using these practical guidelines to engineer a prototype of this unique concept. “Working with nanostructures is a wonderful way to open paths that could overcome the limits set by conventional physics,” he notes.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Microelectronics
 Wong, S. M. et al. Design high-efficiency Si nanopillar-array-textured thin-film solar cell. IEEE Electron Device Letters 31, 335–337 (2010).
Researchers take next step toward fusion energy
16.11.2017 | Texas A&M University
Desert solar to fuel centuries of air travel
16.11.2017 | SolarPACES
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses