Tandem solar cells with perovskite: nanostructures help in many ways
Scanning electron microscopy of perovskite silicon tandem cells in cross-section with nanotexture and back-reflector layer (golden). © P. Tockhorn/HZB
By the end of 2021, teams at HZB had presented perovskite silicon tandem solar cells with an efficiency close to 30 percent. This value was a world record for eight months, a long time for this hotly contested field of research. In the renowned journal Nature Nanotechnology, the scientists describe how they achieved this record value with nanooptical structuring and reflective coatings.
Tandem solar cells made of perovskite and silicon enable significantly higher efficiencies than silicon solar cells alone. Tandem cells from HZB have already achieved several world records. Most recently, in November 2021, HZB research teams achieved a certified efficiency of 29.8 % with a tandem cell made of perovskite and silicon. This was an absolute world record that stood unbeaten at the top for eight months. It was not until the summer of 2022 that a Swiss team at EPFL succeeded in surpassing this value.
Joined forces
Three HZB teams had worked closely together for the record-breaking tandem cell. Now they present the details in Nature Nanotechnology. The journal also invited them to write a research briefing, in which they summarise their work and give an outlook on future developments.
Textures improves the performance
"Our competences complement each other very well," says Prof. Dr. Christiane Becker, who developed the world record cell with the team led by Dr. Bernd Stannowski (silicon bottom cell) and Prof. Dr. Steve Albrecht (perovskite top cell). Becker's team introduced a nanooptical structure into the tandem cell: a gently corrugated nanotexture on the silicon surface. "Most surprising, this texture brings several advantages at once: it reduces reflection losses and ensures a more regular perovskite film formation," says Becker. In addition, a dielectric buffer layer on the back of the silicon reduces parasitic absorption at near-infrared wavelengths.
As a conclusion, the researchers hold: customised nanotextures can help to improve perowskite semiconductor materials on diverse levels. These results are not only valuable for tandem solar cells made of perovskite and silicon, but also for perovskite-based light-emitting diodes.
- HZB receives funding to make innovations usable more quicklyThe Helmholtz Association has selected three new innovation platforms that will now be funded. HZB is involved in two of them: The Innovation Platform on Accelerator Technologies HI-ACTS is intended to open up modern accelerators for a wide range of applications, while the Innovation Platform Solar TAP is intended to bring new ideas from the laboratories of photovoltaics research more quickly into an application. In total, HZB will receive 4.2 million euros in grants from the Pact for Research and Innovation over the next three years.
- Urban Innovation Forum 2023Urban Innovation Forum UIF 2023 brings together a diverse group of urban innovators, thought leaders, entrepreneurs and advocates to explore how breakthroughs in urban tech can accelerate the sustainable transformation of urban spaces.
Join the Session on 30 March 2023
02:45 - 03:30 pm GREEN BUILDINGS & PROPTECH
How do we decarbonize the energy system of the building stock, infrastructure, and cities? How do we create Business showcases in a decentralized and sustainable energy generation. How do we reach the energy efficiency of residential and commercial buildings?
Speakers:
// Samira Aden, Helmholtz-Zentrum Berlin // Karolina Attspodina, WeDoSolar // Fabian Reetz, Everyone Energy //Gerrit Peters, Below2 // Moderation: Totinia Hörner
The UIF 2023 is a partner event of the Berlin Energy Transition Dialogue (BETD) from the Federal Goverment.
- Green hydrogen: How photoelectrochemical water splitting may become competitiveSunlight can be used to produce green hydrogen directly from water in photoelectrochemical (PEC) cells. So far, systems based on this "direct approach" have not been energetically competitive. However, the balance changes as soon as some of the hydrogen in such PEC cells is used in-situ for a catalytic hydrogenation reaction, resulting in the co-production of chemicals used in the chemical and pharmaceutical industries. The energy payback time of photoelectrochemical "green" hydrogen production can be reduced dramatically, the study shows.