Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Converts One-third of the Sunlight into Electricity: 33.3 % Silicon-based Multi-junction Solar Cell

03.04.2018

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with the company EV Group (EVG) have developed a new silicon-based multi-junction solar cell, which can convert exactly one-third of the incident sunlight into useful electricity. This newest result is now published in the renowned scientific magazine Nature Energy.

Silicon solar cells dominate the global photovoltaic market today with a share of 90 percent. With ever new technological developments, research and industry are nearing the theoretical efficiency limit for semiconductor silicon. At the same time, they are forging new paths to develop a new generation of even more efficient solar cells.


Silicon-based multi-junction solar cell consisting of III-V semiconductors and silicon. The record cell converts 33.3. percent of the incident sunlight into electricity.

© Fraunhofer ISE/Photo: Dirk Mahler

The Fraunhofer researchers achieved the high conversion efficiency of the silicon-based multi-junction solar cell with extremely thin 0.002 mm semiconductor layers of III-V compound semiconductors, bonding them to a silicon solar cell. To compare, the thickness of these layers is less than one twentieth the thickness of a human hair.

The visible sunlight is absorbed in a gallium-indium-phosphide (GaInP) top cell, the near infrared light in gallium-arsenide (GaAs) and the longer wavelengths in the silicon subcell. In this way, the efficiency of silicon solar cells can be significantly increased.

“Photovoltaics is a key pillar for the energy transformation,” says Dr. Andreas Bett, Institute Director of Fraunhofer ISE. “Meanwhile, the costs have decreased to such an extent that photovoltaics has become an economically viable competitor to conventional energy sources.

This development, however, is not over yet. The new result shows how material consumption can be reduced through higher efficiencies, so that not only the costs of photovoltaics can be further optimized but also its manufacture can be carried out in a resource-friendly manner.”

Already in November 2016, the solar researchers in Freiburg together with their industry partner EVG demonstrated an efficiency of 30.2 percent, increasing it to 31.3 percent in March 2017. Now they have succeeded once again in greatly improving the light absorption and the charge separation in silicon, thus achieving a new record of 33.3 percent efficiency. The technology also convinced the jury of the GreenTec Awards 2018 and has been nominated among the top three in the category “Energy.”

The Technology

For this achievement, the researchers used a well-known process from the microelectronics industry called “direct wafer bonding” to transfer III-V semiconductor layers, of only 1.9 micrometers thick, to silicon. The surfaces were deoxidized in a EVG580® ComBond® chamber under high vacuum with a ion beam and subsequently bonded together under pressure. The atoms on the surface of the III-V subcell form bonds with the silicon atoms, creating a monolithic device. The complexity of its inner structure is not evident from its outer appearance: the cell has a simple front and rear contact just as a conventional silicon solar cell and therefore can be integrated into photovoltaic modules in the same manner.

The III-V / Si multi-junction solar cell consists of a sequence of subcells stacked on top of each other. So-called “tunnel diodes” internally connect the three subcells made of gallium-indium-phosphide (GaInP), gallium-arsenide (GaAs) and silicon (Si), which span the absorption range of the sun’s spectrum. The GaInP top cell absorbs radiation between 300 and 670 nm. The middle GaAs subcell absorbs radiation between 500 and 890 nm and the bottom Si subcell between 650 and 1180 nm, respectively. The III-V layers are first epitaxially deposited on a GaAs substrate and then bonded to a silicon solar cell structure. Here a tunnel oxide passivated contact (TOPCon) is applied to the front and back surfaces of the silicon. Subsequently the GaAs substrate is removed, a nanostructured backside contact is implemented to prolong the path length of light. A front side contact grid and antireflection coating are also applied.

On the way to the industrial manufacturing of III-V / Si multi-junction solar cells, the costs of the III-V epitaxy and the connecting technology with silicon must be reduced. There are still great challenges to overcome in this area, which the Fraunhofer ISE researchers intend to solve through future investigations. Fraunhofer ISE’s new Center for High Efficiency Solar Cells, presently being constructed in Freiburg, will provide them with the perfect setting for developing next-generation III-V and silicon solar cell technologies. The ultimate objective is to make high efficiency solar PV modules with efficiencies of over 30 percent possible in the future.

Project Financing

Dr. Roman Cariou, the young scientist and first author, was supported through the European Union with a Marie Curie Stipendium (HISTORIC, 655272). The work was also supported by the European Union within the NanoTandem project (641023) as well as by the German Federal Ministry for Economic Affairs and Energy BMWi in the PoTaSi project (FKZ 0324247).

Weitere Informationen:

https://doi.org/10.1038/s41560-018-0125-0 Article in "Nature Energy": III–V-on-silicon solar cells reaching 33% photoconversion efficiency in two-terminal configuration

Karin Schneider | Fraunhofer-Institut für Solare Energiesysteme ISE
Further information:
http://www.ise.fraunhofer.de/

More articles from Power and Electrical Engineering:

nachricht New explanation for sudden heat collapses in plasmas can help create fusion energy
31.03.2020 | DOE/Princeton Plasma Physics Laboratory

nachricht Double-walled nanotubes have electro-optical advantages
30.03.2020 | Rice University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A sensational discovery: Traces of rainforests in West Antarctica

90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous

An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...

Im Focus: Blocking the Iron Transport Could Stop Tuberculosis

The bacteria that cause tuberculosis need iron to survive. Researchers at the University of Zurich have now solved the first detailed structure of the transport protein responsible for the iron supply. When the iron transport into the bacteria is inhibited, the pathogen can no longer grow. This opens novel ways to develop targeted tuberculosis drugs.

One of the most devastating pathogens that lives inside human cells is Mycobacterium tuberculosis, the bacillus that causes tuberculosis. According to the...

Im Focus: Physicist from Hannover Develops New Photon Source for Tap-proof Communication

An international team with the participation of Prof. Dr. Michael Kues from the Cluster of Excellence PhoenixD at Leibniz University Hannover has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.

A 15-member research team from the UK, Germany and Japan has developed a new method for generating and detecting quantum-entangled photons at a wavelength of...

Im Focus: Junior scientists at the University of Rostock invent a funnel for light

Together with their colleagues from the University of Würzburg, physicists from the group of Professor Alexander Szameit at the University of Rostock have devised a “funnel” for photons. Their discovery was recently published in the renowned journal Science and holds great promise for novel ultra-sensitive detectors as well as innovative applications in telecommunications and information processing.

The quantum-optical properties of light and its interaction with matter has fascinated the Rostock professor Alexander Szameit since College.

Im Focus: Stem Cells and Nerves Interact in Tissue Regeneration and Cancer Progression

Researchers at the University of Zurich show that different stem cell populations are innervated in distinct ways. Innervation may therefore be crucial for proper tissue regeneration. They also demonstrate that cancer stem cells likewise establish contacts with nerves. Targeting tumour innervation could thus lead to new cancer therapies.

Stem cells can generate a variety of specific tissues and are increasingly used for clinical applications such as the replacement of bone or cartilage....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

13th AKL – International Laser Technology Congress: May 4–6, 2022 in Aachen – Laser Technology Live already this year!

02.04.2020 | Event News

“4th Hybrid Materials and Structures 2020” takes place over the internet

26.03.2020 | Event News

Most significant international Learning Analytics conference will take place – fully online

23.03.2020 | Event News

 
Latest News

AI finds 2D materials in the blink of an eye

02.04.2020 | Information Technology

New 3D cultured cells mimic the progress of NASH

02.04.2020 | Health and Medicine

Graphene-based actuator swarm enables programmable deformation

02.04.2020 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>