Steve Albrecht’s pioneering research in perovskite-based solar cells is revolutionizing photovoltaics and sustainable energy conversion. Overcoming the limitations of traditional silicon-based solar cells, Albrecht’s team has achieved remarkable efficiency levels, setting world records and breaking barriers. Their innovative approach to solar energy conversion involves tandem configurations, combining perovskite with silicon or thin-film materials to enhance efficiency beyond the limits of silicon. With a commitment to energy equality, security, and sustainability, Albrecht’s breakthroughs hold the promise of a greener future.

Which wall does your research break?

Throughout the history of the PV industry, the conversion of sunlight to electricity on a commercial scale has been limited to less than 27%. This is close to the practical and theoretical limits of silicon, which is the mainstay of the PV industry. Almost all alternative materials that have been researched over decades have either not been competitive in performance or have been too intolerant to defects or only being affordable for space applications (i.e. 100x-1000x cost of terrestrial devices). Our team has made remarkable strides in the use of perovskite-based architectures, which have been hailed as the most exceptional materials available. Their optical and electronic properties and high tolerance to defects in fabrication make them outstanding. A micrometre thick film of the material can convert almost as much light to electricity as a 100-200 micrometre wafer of silicon. Moreover, they can be processed in far fewer steps and at lower temperatures (<150 °C instead of 1500 °C for silicon wafers), and can hence, achieve lower costs, material consumption and energy needed for the fabrication. That will also reduce the CO₂ emission of the module fabrication itself. We have set several world records by skilfully fabricating perovskites on top of silicon or thin-film materials to work in a tandem configuration. Such an architecture with a silicon bottom cell is also highly compatible with the existing and rapidly expanding PV industry. Our latest record efficiency of 32.5 % is well beyond the limits of silicon and has lifted our targets to 35 % and beyond. One of our best-known breakthroughs is the development of a single layer of molecules as an extremely efficient layer to collect charges excited by sunlight in the perovskite. This technology is patented but also openly published. Variations of it are actively being used across the world to achieve world records in a variety of perovskite-based solar cells. In addition, we have recently shown that the surface of the perovskite can be treated such that the losses at that interface vanish. This enabled us to break the 30% efficiency barrier for these fascinating tandem cells which made news world-wide. We are therefore breaking the long-standing wall limiting electricity generated from sunlight. We are now also focused on the challenges of scale-up and long-term stability.

What inspired or motivated you to work on your current research or project?

When I started working as a student assistant and later on my diploma thesis, I always wanted to work on solar cells or photovoltaics in general. I was strongly motivated by the fact that the sun delivers way more energy than humanity would ever need. We just need to collect and convert it like plants and some animals do. With that motivation, I was looking for my contribution to that field starting with a very fundamental understanding of the working principles of third generation solar cells to become more applied and industrial relevant over the years. When starting my PhD in 2010, I already focused on the combination of two different solar cell materials into tandem architectures (at that time organic materials and amorphous silicon) to enable performance metrics that are higher than the single materials would have alone. I was fascinated by combining two different materials and utilising them together in a single solar cell device. That means combing two different “worlds” meaning two different scientific communities, different material and solar cell working principles and always two different teams. Developing highly efficient tandem solar cells always meant managing different scientific teams to work together and break “their walls”. Starting with the Postdoc in 2014, I then continued the journey but with different materials namely metal halide perovskites and silicon.

In what ways does society benefit from your research?

Our team and the PV community are currently engaged in ground-breaking research that we believe will greatly enhance the performance of photovoltaics while simultaneously reducing their cost. As a result, we are confident that solar energy will become the primary source of electricity for the majority of the world’s population, with affordable and sustainable benefits for all socio-economic groups and zero emissions. The cost of PV modules has been successfully reduced by 90 % between 2010 and 2020. However, lowering the cost of modules is no longer sufficient to lower the cost of entire PV systems, which include other components such as land area, wiring and installations. Improvements in the performance of modules are needed to lower these external costs, which dominate the total costs today. This is why research and development of perovskites is essential for mitigating climate change. In order to ensure that our research will benefit society on accelerated time scales, we collaborate with industrial partners such as Hanwha Qcells, Meyer Burger, Oxford PV, and Von Ardenne, among others. For example, in the Pepperoni project funded by the European Union and the Swiss federal agency SERI, we are working with 16 partners to build a European pilot line for the perovskite-silicon tandem technology. German chancellor Olaf Scholz highlighted our research as an example of public and private partnership in R&D in a speech at the World Economic Forum this year (2023). It was a special honour to be mentioned in the same context as the first COVID-19 test and vaccine. Furthermore, perovskite-based films require ~1/50th lesser material than silicon, lesser energy and steps in production, and can be built from leaner, diversified supply chains. Silicon supply chains today are highly concentrated and have created critical risks for climate change mitigation and energy industries dependent on them. Geopolitical tensions since 2022 have only served to highlight this issue. If perovskites can be scaled up for industrial use alongside or in competition with silicon, it could lead to the creation of low-risk supply chains, new industries, and millions of jobs.

Looking ahead, what are your hopes or aspirations for the future based on your research or project?

The scientific goals in PV efficiency have been completed with extraordinary success on a small scale. The remaining challenges are now to scale up this efficiency and increase the stability of the solar cells to industrial standards. Through our strong collaboration with the aforementioned industrial leaders, we are working to commercialize perovskite-silicon tandem solar cells. It is widely accepted across the PV industry that this technology has the potential to become the next generation of photovoltaic technologies. Furthermore, we are highly committed to making the next generation of PV easier to produce in terms of cost and energy, and to de-risk the highly concentrated supply chains of today’s PV industry. For this purpose, we are currently establishing a spin-off company with a team of highly diverse and motivated co-founders. The spin-off will work closely with my research group and enhance their scientific breakthroughs with innovative scaling methods. Our unique collaboration model is based on utilizing the talent pool, knowledge, and infrastructure of a scientific research centre. This approach has worked smoothly in our first spin-off, Quantum Yield Berlin GmbH, which provides advanced measurement tools for solar cells and LEDs. We envision a future in which high-efficiency PV modules convert 30-40 % of incident light directly into electricity, powering cities and towns, even from limited spaces such as rooftops and vehicles. We believe that energy is essential to human well-being and must be made accessible to all 8 billion people on the planet while simultaneously phasing out fossil fuels that the richest 2 billion people primarily benefit from. In the future we are working towards, PV factories can be set up and run without enormous investments and will create millions of jobs. With thousands of researchers, and over 30 startups and companies worldwide working on perovskite-based solar cells, we are now in a race to create the PV community’s next big impact in mitigating climate change while also ensuring energy equality, security, and sustainability.

Further Information



[3] National Renewable Energy Laboratory (NREL), “Best research-cell Efficiency Chart”, . HZB occupies four positions post 2019.

[4] Al-Ashouri, Amran, et al. “Monolithic perovskite/silicon tandem solar cell with> 29% efficiency by enhanced hole extraction.” Science 370.6522 (2020): 1300-1309.

[5] Three examples:

(i) Chin, Xin Yu, et al. “Interface passivation for 31.25%-efficient perovskite/silicon tandem solar cells.” Science 381.6653 (2023): 59-63.

(ii) Lin, Renxing, et al. “All-perovskite tandem solar cells with 3D/3D bilayer perovskite heterojunction.” Nature (2023): 1-3.

(iii) Wang, Zaiwei, et al. “Suppressed phase segregation for triple-junction perovskite solar cells.” Nature 618.7963 (2023): 74-79.




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