Capturing Light with Nanoarchitectures

August 20, 2015 ZEISS Microscopy

The Institute for Nanoarchitectures for Energy Conversion at the Helmholtz-Zentrum in Berlin (HZB) was recently made a ZEISS reference lab. ZEISS Microscopy met with head of the Institute Prof. Dr. Silke Christiansen and talked with her about her work on materials and components that comprise nanoscale structures.

Not too long ago, ‘nano’ was the buzzword in the relevant media. In the meantime, it has retreated into the background as terms like Industry 4.0, cloud computing and the Internet of things come to the fore. Nevertheless, a lot is still happening in this area. Several groups of researchers are working on nanotechnologies and nanoscience topics and approaching these from various angles.

Prof. Dr. Silke Christiansen, expert on materials and components with nano-scale structures, and head of the Institute for Nanoarchitectures for Energy Conversion at the Helmholtz-Zentrum in Berlin (HZB) is one of them. For example, she developed procedures to integrate silicon nanowires into thin-layer solar cells as efficient absorbers.

 

Prof. Dr. Silke Christiansen from the Institute for Nanoarchitectures for Energy Conversion using a ZEISS NVision
Prof. Dr. Silke Christiansen from the Institute for Nanoarchitectures for Energy Conversion using ZEISS NVision

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Christiansen’s special area of interest is improved solar energy conversion and storage. “To make solar technologies far more financially viable than they are today, we have to make these technologies even more efficient and further reduce their manufacturing costs. To achieve this, we have to use new and unconventional combinations of nanomaterials and develop new nanoarchitectures and component designs. Basically the entire periodic table of the elements is available to us when we want to create and combine nanomaterials. We are currently still seeing a lot of potential in silicon if we apply everything that we have learned from years of developments in microelectronics to solar energy conversion using silicon. Silicon is well researched and its electrical properties are outstanding. However, it absorbs sunlight very poorly. Therefore, it has to be either combined with other, more absorbent materials, or structured in such a way that it can absorb light more efficiently,” says Christiansen.

Christiansen recently proved for the first time that this research is futureproof. With the aid of specially structured silicon, her team was able to increase the light absorption of thinlayer solar cells just a few micrometers thick by 65%. Funnel-shaped structures are therefore far more efficient at absorbing visible and infrared light than columnshaped structures. The research group examined the structure of the densely packed nano-funnels taken from the retinas of mammals’ eyes. The team, which currently consists of about 20 students and scientists, is concerned not only with the absorption of light, however, but also with energy storage and the efficiency of light sources. For this, the team researches a wide range of materials and compounds, such as graphene and oxide, as well as various nanoarchitectures.

The funnels etched into a silicon substrate are causing an uproar. The shape of the funnels measures on average 800 nanometers at the top and about 100 nanometers at the bottom. Images taken with the ZEISS NVision scanning electron microscope Picture: S. Schmitt/MPL
The funnels etched into a silicon substrate are causing an uproar. The shape of the funnels measures on average 800 nanometers at the top and about 100 nanometers at the bottom. Images taken with the ZEISS NVision scanning electron microscope
Picture: S. Schmitt/MPL

A wide range of nanostructures are produced and optimized in the institute’s own labs. Particularly for material optimization, the team needs powerful electron microscopes and spectroscopes. The latest investments made by Christiansen’s research team at the HZB include the FIB-SEM microscope for nanotomography and nanofabrication, a ZEISS Crossbeam 340, a ZEISS ORION NanoFab ion microscope and a ZEISS MERLIN scanning electron microscope, with the scanning force microscopy enabling the acquisition of information on semiconductors
and nanomaterial samples at atomic resolution. But the teams at the labs do not work on their own topics only. The institute also offers its expertise and technology to partners and external users from science and industry. “Analysis at the nanoscale has become essential in both science and industry. We have samples from a wide range of organic and inorganic materials under our microscopes and spectrometers,” says Christiansen. The research team always finds topics from other disciplines challenging and therefore sees them as a welcome and exciting change. For example, the team has provided support through its expertise and techniques in the examination of the phosphate-calcium compound in the bone formation process, in the analysis of radiation damage in blood cells or in analyzing nanostructures in the field of pharmacy. “We are still at the beginning of this interdisciplinary work. However, we have built up a strong network, gathered large amounts of data on various materials, analyses or simulations and can offer and further develop correlative microscopy and spectroscopy for the various applications. On top of that, with the systems from ZEISS, we are optimally equipped to face new analytical challenges,” says Christiansen. On the basis of its unique expertise, the institute is part of the community of selected ZEISS labs@location reference customers and was recently made part of the new research infrastructure (CoreLabs) of the HZB.

 

 

One thing is immediately obvious, when you meet Christiansen. She is attentive and focused, and she thinks at lightning speed. To her, time is precious! She is a doer and actively pushes her research forward. We invited her for an interview:

Christiansen_short_bio

 

Many scientists leave Germany to do research abroad. You have also worked and conducted research abroad, but later returned to Germany. Why?

Germany or in the US, for example, it makes no difference where you do your research. The real difference is between the budgets that are available to industry and those of the scientific research landscape. Nevertheless, there is a lot of money in the system at the national, European and international level. It’s just that it’s much more timeconsuming to access these funds than those in industry. Scientists need a good network and contacts, as well as topics that have scientific relevance. The German research landscape boasts a lot of attractive research institutes with good budgets. But you have to be pro-active as a scientist and sell yourself. To date, I have been able to achieve everything that was necessary in order to push our research onwards.

You have become part of the ZEISS community labs@location and use many of our systems. Why?

The partnership with ZEISS has many benefits for me. For one thing, our institute is widely regarded as an excellence lab. A good reputation helps us – for instance when it comes to research funding. The size of ZEISS and its location in Germany is also beneficial. We speak the same language, trust each other and know that shared topics are handled quickly. I can depend on service engineers to get to us quickly and make sure our systems are operational. After all, our research is our capital. However, labs@location also means that we deal with potential ZEISS customers – speaking with them about applications and systems or producing samples. We can learn a lot in this area and adapt the learnings to our own research and develop new applications.

What advice would you give to young female graduates who want to work in  science?

Women and men can achieve the same things. To me, there is no doubt about that. The circumstances and priorities one sets as a woman are more to the point. How would I like to shape my private life? Do I want children? What kind of mother would I like to be? Having asked myself these questions, I decided to have children and a career in science – but also maintain a realistic outlook and practice good time management with the support of family and friends. Young scientists should face these issues at an early stage.

Read more about ZEISS microscopes used for the analysis of nanoscale structures:

ZEISS Crossbeam 340

ZEISS ORION NanoFab

ZEISS MERLIN

 

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