© HZB
Science for Kenya
The synthesis of the nanomaterials.
© Vincent Bungei
The washing of the materials.
© Vincent Bungei
Robert (right) cleans in an ultrasonicator the substrates to be used in solar cell fabrication.
© Mercy Chebwogen
The BESSY@HZB User Meeting welcomes 17 scientists from Kenya. They come from six different universities. One of them is Robert Ngure; he is a Master’s student in material science at Egerton university. He tells us more about his fascination for science and what he expects from his visit to Adlershof.
Robert Ngure graduated in June 2019 and enrolled a few months later for a Master’s degree in science. In most universities in Kenya, you study for one year before you choose a specialisation. Robert’s decision was relatively straightforward: “I am convinced that material science is very relevant for my country. From the beginning, my goal is to drive forward the energy conversion.”
Robert works in Tabitha’s material science group at Egerton university, Kenya, and thanks to this connection, he also got in contact with Lucy Ombaka. Finally, he met “Dr. Antje when she came to Egerton in November 2022”. “She spoke with such enthusiasm of BESSY II; discovering my research topic at HZB was fascinating. Some of my teams work on organic solar cells. This is extremely interesting, and I am keen on developing novel nanocomposites of solar cells,” says the student. Even at this early stage in his career, the scientist is passionate about material science. He calls his discovery of BESSY II light source an “eye-opener.”
Solar Energy Made in Adlershof
In spring 2023, he attended the HZB-Photon School in Adlershof with Nancy. During two weeks, a group of students had lectures and could do some hands-on experiments at BESSY II. “My research work is on the synthesis and characterisation of nanocomposites. The idea here is to synthesize nanocomposites using graphene and, in my case, silver-based nanoparticles.
Robert adds: “During the photon school, I learnt a lot about data analysis. I also had the privilege to see the PV competence center in Adlershof, a very inspiring place. They showed different ways of implementing photovoltaics.”
Expectations and Dreams
Robert is very excited to meet other experts in his field end of June at the BESSYII@HZB User Meeting: “I would like to talk about better materials and learn new advanced methods.”
The scientist has a big vision: “My dream is that every household in Kenya should have a renewable energy source. To my mind, access to affordable solar cells for everybody is urgent! There is some hydroelectric; however, this does not reach all people. Right now, some people use kerosene for lighting. I really recommend the mass production of organic solar cells – there is so much sun over here, solar energy is basically free!”
This blogpost is part of a series on our cooperation with scientists from Kenya.
And here, you can find the website of Tabitha’s material science group.
- Magnetic imaging: Micro-flowers increase the local magnetic fieldMaterials with magnetic nanostructures have many potential applications such as in spintronics. To explore such materials, nanoscale magnetic-sensitive imaging techniques are very useful, but up to now only weak magnetic fields could be applied during the imaging process. Now an international collaboration led by Dr. Sergio Valencia, HZB, has developed an approach that overcomes this limitation. The team designed tiny magnetic flux concentrators (MFCs), into which the sample is placed. The geometry of the MFCs resembles a flower with a number of petals which focus the applied magnetic field into its center. This greatly expands the magnetic field range available during imaging, and so the range of magnetic systems that can be investigated. The micro-flowers, enhancing magnetic fields locally, can find application in different nanometric magnetic microscopy techniques.
- CIGS-perovskite tandem cell achieves record efficiency of 25.5 %A Berlin-based team from HZB and Center for the Science of Materials Berlin (CSMB) at the Humboldt-Universität zu Berlin has set a new record for a tandem solar cell. Using a combination of a CIGS semiconductor layer and perovskite, along with several optimised intermediate layers, they were able to convert 25.5% of sunlight into electrical energy. The previous record for this combination of materials and this size of cell stood at 24.6%. The new record has been certified and is visible in the prestigious Solar Cell Efficiency Tables (the "Green Tables"), which serve as the definitive ledger for the global photovoltaic community.
- Disorder creates new properties in compound semiconductorsAn international research team has demonstrated that the intrinsic disorder of the compound semiconductor CuInSnS₄ can be exploited to influence its optical properties. While the atomic vibrations also sense the local disorder, their response is averaged over many different local environments and therefore appear isotropic, as expected for a cubic crystal. In contrast, the optical excitations, known as excitons, are much more sensitive to the local arrangement of atoms. Surprisingly, they show a direction-dependent optical response even though the average crystal structure is cubic. These findings shed new light on the relationship between disorder and material properties, opening up new options for targeted 'disorder engineering' in optoelectronic and photocatalytic devices.