How Can We Improve the Efficiency of Multi-Junction Solar Cells? NREL Research

Multi-junction solar cells have been gaining attention due to their ability to capture and convert a broader range of the solar spectrum into electricity compared to single-junction cells. One of the most recent breakthroughs in this field has been achieved by researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), who created a solar cell with a record 39.5% efficiency under 1-sun global illumination. This article explores the advancements and techniques used to enhance the efficiency of multi-junction solar cells.

Quantum Well Solar Cells: The Key to Enhanced Efficiency

The NREL team developed a quantum well solar cell with unprecedented performance, focusing on modifying solar cell properties by utilizing many very thin layers. They implemented this technology into a device with three junctions, each with different bandgaps. These junctions were specifically designed to capture and utilize different slices of the solar spectrum, leading to higher overall efficiency.

III-V Materials: Expanding the Solar Spectrum Coverage

The new solar cell relies on III-V materials, known for their high efficiency and wide range of energy bandgaps. These materials, named after their positions on the periodic table, include gallium indium phosphide (GaInP), gallium arsenide (GaAs) with quantum wells, and lattice-mismatched gallium indium arsenide (GaInAs). Over decades of research, each material has been optimized to maximize its performance within multi-junction solar cells.

Optimizing Bandgaps with Quantum Wells

A crucial aspect of the NREL team’s work was their use of quantum wells in the middle layer of the solar cell to extend the bandgap of the GaAs cell. This innovation increased the amount of light the cell could absorb and further improved efficiency. The researchers developed optically thick quantum well devices without significant voltage loss, a critical step in optimizing the cell design.

Reducing Manufacturing Costs and Expanding Applications

Despite their high efficiency, III-V solar cells have been expensive to manufacture, limiting their use to niche applications like space satellites and unmanned aerial vehicles. NREL researchers have been working on reducing manufacturing costs and providing alternative cell designs to make these cells more economical for a broader range of applications.

Space Applications: Efficiency for Communications Satellites

The new III-V cell has also been tested for its suitability in space applications, particularly for communications satellites that rely on solar cells for power. The cell demonstrated a 34.2% efficiency for beginning-of-life measurements in low-radiation environments, making it a promising option for powering satellites and other space applications.


The development of the high-efficiency multi-junction solar cell by NREL researchers represents a significant step forward in solar cell technology. By incorporating quantum well solar cells, optimizing III-V materials, and extending bandgaps, the team achieved a record 39.5% efficiency under 1-sun global illumination. As researchers continue to refine manufacturing processes and reduce costs, multi-junction solar cells could become increasingly practical and attractive for a wider range of applications, both on Earth and in space.

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What are the Latest Developments in Organic Solar Cells? A Closer Look at UTD’s Research

The quest for clean, renewable energy sources has led to extensive research in the field of solar energy. Among the various technologies being developed, organic solar cells (OSCs) have garnered considerable interest due to their potential to revolutionize the solar energy landscape. Unlike traditional silicon-based solar cells, OSCs are made from organic polymers and molecules, which could significantly reduce the cost of solar panels. In this article, we will discuss the latest developments in the field of organic solar cells, with a focus on the groundbreaking research conducted by the University of Texas at Dallas (UTD).

1. UTD’s Research on Dilute-Donor Organic Solar Cells

    A team of researchers from UTA discovered a method to increase the efficiency of OSCs by altering the composition of donor and acceptor materials. The new cells, called dilute-donor cells, contain as little as 1% to 5% donor material. This change in composition has shown promise for yielding high voltage and high current. The UTA researchers also found that changing the shape of the donor material from chips to strands further improved the efficiency of the OSCs.

    2. UTD’s Collaborations and International Contributions

      The research conducted by UTA has involved collaborations with researchers from the Giulio Natta Institute of Chemical Sciences and Technologies in Italy and the Technical University of Munich. These international collaborations have helped advance the understanding of organic solar cell technology and contributed to the development of novel materials and device structures.

      3. UTD’s Use of Advanced Computational Simulations

        One of the researchers on the UTA team, developed computer simulations that led to the discovery of the optimal donor material shape for increased efficiency in OSCs. These simulations have provided valuable insights into the operation of OSCs, enabling researchers to optimize the materials and device structures for improved performance.

        4. UTD’s Focus on Advancing Less Understood Properties of OSCs

          The UTD team’s findings advance a less understood property of organic solar cell technology called the fill factor, which is the ratio of the amount of power the cell could theoretically obtain to the actual current. A better understanding of the fill factor can lead to further improvements in OSC efficiency.

          5. UTD’s Research on Halide Perovskite Solar Cells

            In addition to their work on organic solar cells, UTD researchers have also conducted extensive research into solar energy, including on solar cells made from another material called halide perovskite. This research has further contributed to the development of a portfolio of different types of renewable energy sources.


            The latest developments in organic solar cells, particularly the research conducted by the University of Texas at Dallas, hold great promise for the future of renewable energy. The advancements in OSC technology, such as dilute-donor cells, improved efficiency, and increased understanding of less known properties, pave the way for further innovations in the field. As the research continues, OSCs have the potential to become a significant player in the global renewable energy market, contributing to a more sustainable future.

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