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).
Electrical fields drive nano-machines a 100,000 times faster than previous methods
19.01.2018 | Technische Universität München
ISFH-CalTeC is “designated test centre” for the confirmation of solar cell world records
16.01.2018 | Institut für Solarenergieforschung GmbH
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy