Researchers from the University of the Basque Country (EHU) are pioneering innovative solutions to enhance the performance of CSP systems. Their current exploration involves ultrablack materials designed for use in solar power towers, which rely on mirrors to focus sunlight onto a central tower where energy is absorbed. The efficiency of these systems hinges on the effectiveness of the absorbing materials, which need to be capable of retaining as much solar energy as possible. As noted by Iñigo González de Arrieta, a member of the Thermophysical Properties of Materials research group at EHU, developing efficient absorbing materials can significantly reduce costs and expand the viability of CSP technology.

The design and testing of these advanced materials utilize cutting-edge laboratories and techniques. The researchers are conducting thermo-optical analyses to quantify the absorption properties of various samples. The EHU lab is one of the few dedicated facilities worldwide for high-temperature research, positioning the team as leaders in pushing the boundaries of CSP material efficiency.

In their research, the EHU team has evaluated copper cobaltate nanoneedles, a promising material patent developed by the University of California San Diego. Dr. González de Arrieta highlighted the superior performance of these nanoneedles compared to traditional carbon nanotubes, which have been the standard in high-efficiency solar absorbers. The copper cobaltate nanoneedles exhibited a remarkable coupling with zinc oxide, showing enhanced absorption characteristics, thus presenting a significant leap forward in material design for solar towers.

The primary goal in CSP technology is to achieve maximal light absorption. The mirrors direct sunlight towards the tower, and achieving a high absorption capacity of the materials placed therein is crucial. Current leading materials include vertically aligned carbon nanotubes, which, despite their optical advantages, suffer from stability issues under high thermal conditions and humidity. Their requirement for protective coatings leads to a decrease in optimization potential. In contrast, copper cobaltate nanoneedles provide enhanced stability at elevated temperatures, addressing a key challenge in using carbon nanotubes for solar energy applications.

As Gonzalez de Arrieta mentions, these innovative nanoneedles absorb significantly more solar energy compared to existing solutions. While carbon nanotubes manage to absorb around 99% of the light, the new copper cobaltate nanoneedles achieve up to 99.5% absorption rate, providing an essential improvement in the efficiency and performance of CSP systems. This breakthrough is vital, especially when the thermal energy stored in these systems can subsequently be utilized even when direct sunlight is unavailable.

Current solar tower installations, particularly in regions such as Andalusia and various desert landscapes around the globe, only contribute a small fraction of the overall energy supply in their respective countries. In Spain, for example, CSP technologies provide just a modest 5% contribution to the energy mix. Nevertheless, the potential benefits of expanding this technology are immense, especially considering its clean energy production capacity and its ability to generate power even during non-sunny periods.

While experimental applications of copper cobaltate nanoneedles are still under investigation, cooperation with researchers in the United States, including Dr. Renkun Chen at UC San Diego, is ongoing. Together with the U.S. Department of Energy, these collaborations aim to integrate the nanoneedles into actual solar tower projects, though uncertainties in the U.S. energy landscape pose challenges to this initiative.

As the EHU researchers continue their critical work in developing and characterizing materials for CSP applications, it becomes increasingly clear that ongoing innovation is necessary. There lies a compelling need for further exploration into novel coatings and materials that could facilitate enhanced conductivity and optical properties. Such advancements hold the promise of transforming the solar energy landscape and significantly boosting sustainability efforts globally.

Moreover, the Thermophysical Properties of Materials group at EHU is composed of experts from the interdisciplinary fields within the Department of Physics and various Engineering faculties. This comprehensive approach allows for a holistic investigation of the challenges faced in thermophysics and materials science, enabling cohesive solutions to complex energy problems.

As society increasingly recognizes the importance of transitioning to renewable energy resources, research such as that conducted by the EHU team exemplifies the crucial role of academic institutions in driving technological advancement. The knowledge generated through such studies not only contributes to scientific literature but also serves to inform policy decisions related to renewable energy strategies.

In summary, the shift towards increased adoption of concentrated solar power is further rejuvenated by ongoing research into ultrablack materials that promise unparalleled efficiency in energy absorption. By focusing on stability, efficiency, and innovative material design, researchers can facilitate a more extensive integration of renewable energy technologies, leading society toward a sustainable and resilient energy future.

Subject of Research: Ultralight Nanoneedles for Concentrated Solar Power
Article Title: AZO-coated refractory nanoneedles as ultra-black wide-angle solar absorbers
News Publication Date: 31-Jul-2025
Web References: https://doi.org/10.1016/j.solmat.2025.113840
References: González de Arrieta, I.; Echániz, T.; Rubin, E.B.; Chung, K.M.; Chen, R.; López, G.A.
Image Credits: Egoi Markaida

Keywords

Alternative energy, Energy resources, Solar energy, Applied sciences and engineering.

Perovskite solar cells represent a revolutionary approach in the realm of photovoltaic technology. They exhibit remarkable light-absorbing capabilities, which make them a solid contender to overcome the limitations of conventional crystalline silicon solar cells. While silicon-based cells dominate the market due to their affordability and widespread manufacturing capabilities, they have begun to plateau in efficiency as they reach their theoretical limits. In contrast, tandem solar cells that pair silicon with perovskite materials have emerged as promising alternatives, significantly enhancing overall energy conversion rates.

The unique composition of tandem solar cells allows for greater versatility in application, particularly in sectors where the adaptability and lightweight properties of solar panels are essential. Traditional perovskite/silicon cells, despite achieving efficiency rates as high as 34.6%, face challenges concerning weight and damage susceptibility. These problems hinder their application in contexts such as aerospace and automotive industries, where weight considerations and structural integrity are critical.

In an effort to address these challenges, the innovative work by the KIER research team has led to the development of flexible thin-film perovskite/CIGS tandem solar cells. CIGS, known for being lightweight and flexible, is particularly suitable for integration into curved surfaces represented in modern architecture, vehicles, and other innovative applications. However, previous iterations suffered from lower efficiency rates and complex manufacturing processes, creating barriers to market readiness.

The KIER team’s novel approach involved a simple lift-off process. This methodology entails coating a polyimide layer onto a glass substrate before fabricating the perovskite/CIGS tandem solar cell atop the polyimide. The lift-off process allows for stable and uniform layer deposition which leads to significantly higher reproducibility and efficiency compared to traditional methods. The rigid glass substrate utilized in this process enhances the stability during fabrication and ultimately contributes to the performance improvement of the solar cells.

Moreover, the team identified a critical improvement mechanism during the fabrication process that involves managing the diffusion of alkali metals from the glass substrate into the CIGS layer. Excessive diffusion of potassium, in particular, can introduce defects in the absorber layer, negatively impacting the overall efficiency of the solar cells. To combat this issue, the researchers leveraged computational science to predict that the polyimide layer could effectively suppress potassium diffusion, resulting in fewer defects and a marked increase in performance.

Not only did the innovative fabrication process contribute to efficiency gains, but it also provided the new cells with outstanding durability. The research team undertook rigorous mechanical testing, performing 100,000 bending cycles to evaluate the resilience of the solar cells. Impressively, the cells maintained an efficiency of 97.7% post-testing, showcasing their robustness and suitability for challenging real-world applications.

Dr. Inyoung Jeong emphasized the significance of this achievement, noting that it lays the groundwork for future advancements toward a goal of achieving 30% efficiency in ultralight flexible solar cells. The implications of this work are vast, with the potential to expand applications in renewable energy, particularly in highly portable and adaptable modules.

Dr. Kihwan Kim, another prominent figure in the research, highlighted the power-to-weight ratio associated with the new solar cells, stating it is approximately ten times greater than traditional perovskite/silicon tandem solar cells. This breakthrough promises to enable innovative applications in demanding environments, such as in building exteriors and on vehicles, where every gram counts, and efficiency is paramount.

The research results were published in the prestigious journal Joule, which underscores the high impact of this discovery on the field of energy and materials science. This accomplishment was made possible through a collaborative effort involving distinguished scholars like Professor Tae Kyung Lee of Gyeongsang National University and Professor Hae-Jin Kim of Yonsei University, showcasing the strength of collaborative research in driving technological advancements.

As renewable energy solutions continue to shape a sustainable future, the ultra-lightweight flexible perovskite/CIGS tandem solar cells developed by KIER serve as a formidable step toward overcoming existing barriers in solar cell technology. Their impressive efficiency, durability, and lightweight nature present an exciting prospect for the future of energy generation, particularly as industries strive for greener alternatives in a world increasingly reliant on sustainable solutions.

With ongoing efforts to refine manufacturing processes and enhance the stability of these solar cells, the KIER research team aims to fortify the competitiveness of the renewable energy sector. This breakthrough not only contributes to advancing solar technology but also signals the potential for widespread adoption of renewable energy solutions across various industries, ensuring a sustainable energy future.

The study not only sheds light on the technical advancements in solar technology but also holds promise for spurring innovations that can lead to more efficient, adaptable, and sustainable energy practices globally. As researchers continue to explore the possibilities of combining cutting-edge materials and technologies, the future of solar energy looks bright, offering endless opportunities for innovation in the pursuit of clean energy.

Subject of Research: Development of ultra-lightweight flexible perovskite/CIGS tandem solar cells
Article Title: Flexible and lightweight perovskite/Cu(In,Ga)Se2 tandem solar cells
News Publication Date: 19-Mar-2025
Web References: DOI link
References: Joule Journal, March 2025
Image Credits: KOREA INSTITUTE OF ENERGY RESEARCH(KIER)

Keywords

solar energy, perovskite cells, CIGS, renewable energy, efficiency, lightweight technology, advanced materials, energy research, photovoltaic technology.