Perovskite Solar - Page 48

Researchers at  the University of Oxford and the University of Potsdam have combined theoretical and experimental approaches to understand and reduce the losses of wide bandgap Br-rich perovskite pin devices at open-circuit voltage (VOC) and short-circuit current (JSC) conditions.

A mismatch between the internal quasi-Fermi level splitting (QFLS) and the external VOC is detrimental for these devices. The team demonstrated that modifying the perovskite top-surface with guanidinium-Br and imidazolium-Br forms a low-dimensional perovskite phase at the n-interface, suppressing the QFLS-VOC mismatch, and boosting the VOC.

Researchers at Huazhong University of Science and Technology, Wuhan University of Technology and University of Toronto recently introduced a new approach for fabricating more stable 3D/2D heterostructures, preventing their degradation. Their approach is based on the introduction of an additional layer between the structures; 3D and 2D perovskite layers.

2D and quasi-2D modified 3D perovskite heterostructures (i.e., structures comprised of 3D and 2D perovskite materials) have several advantageous qualities, such as enabling the passivation of defects and a favorable band alignment, which improve a perovskite solar cells' open-change voltage and fill factor. 3D/2D heterostructures are typically created by spin coating an organic cation salt solution on top of a 3D perovskite material and forming a thin 2D perovskite layer on its surface. This process, however, can facilitate the subsequent degradation of the heterostructures in some conditions, due to the diffusion of ions between the 2D perovskite surface and underlying bulk 3D perovskite.

Project SUNREY (”Boosting SUstaiNability, Reliability and EfficiencY of perovskite PV through novel materials and process engineering”) is a three-year project which started on November 1, 2022. It is coordinated by the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam, Germany. The project aims to further the development of highly-efficient solar cells based on non-critical raw materials (with a focus on making perovskite solar cells more sustainable, efficient and durable) and to strengthen the innovation potential of the European industry. 

SUNREY is funded by the European Union’s research and innovation program Horizon Europe within the framework of the Green Deal Initiative with 4.25 Million Euro. 

Scientists from Skoltech (Skolkovo Institute of Science and Technology), Research Centre for Medical Genetics, Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry and Zhengzhou Research Institute of HIT have studied the toxicity of materials used in perovskite solar cells.

They concluded that once the remaining technological hurdles are overcome, mass production of this potentially cheap and efficient alternative to silicon-based photovoltaics should not cause any significant environmental risks and health hazards. The study draws attention to perovskite components other than lead, suggesting that metal's toxicity, by comparison, could be overestimated.

Nano-textured surfaces are an interesting approach for optimizing the optical characteristics for monolithic perovskite/silicon tandem solar cells. Scientists from Germany’s Helmholtz-Zentrum Berlin (HZB) have examined the development of different textures of silicon surfaces using various commercial additives and their performance in silicon heterojunction (SHJ) and SHJ–perovskite tandem solar cells.

The team performed optical and electrical characterization and found that nano-textured surfaces can compete with standard textured surfaces, yielding higher average efficiencies in single junctions. In addition, their compatibility with solution-processed perovskite top cells was demonstrated in the recent study, yielding a perovskite/silicon tandem solar cell efficiency of >28% on a bottom cell with nano-texture on both sides.

The SuPerTandem project started in October 2022, for a period of 36 months. It received EC project contribution of €4,930,196.25. The project includes 15 partners from 8 countries – top research institutions, universities and industrial producers of perovskite photovoltaic modules, equipment producers, and an industry leader in laser micromachining that put their effort together to maximize the efficiency of perovskite solar cells. 

In March 2023, a project meeting was held, after which the team drafted a press release that updated: "The SuPerTandem project team is working on a breakthrough perovskite photovoltaic tandem technology with the aim to offer to the solar energy market a perovskite solar panel which is affordable for only 20 EUR per square meter, made of low-cost, widely available raw materials and manufactured by low carbon footprint production process".

Researchers at South Korea’s Ulsan National Institute of Science and Technology (UNIST), Chonnam National University and Pohang University of Science and Technology (POSTECH) have developed a unique perovskite solar cell that uses alkylammonium chloride (RACI) to control the formation of defects in the perovskite layer.

The US National Renewable Energy Laboratory (NREL) has certified the South Korean research team's cell's 25.73% efficiency. The champion device built by the scientists reached an efficiency of 26.08%.

Researchers from North Carolina State University, Pennsylvania State University and University of North Carolina at Chapel Hill have found that channeling ions into defined pathways in perovskite materials improves the stability and operational performance of perovskite solar cells. 

The team's recent study presented a multiscale diffusion framework that describes vacancy-mediated halide diffusion in polycrystalline metal halide perovskites, differentiating fast grain boundary diffusivity from volume diffusivity that is two to four orders of magnitude slower. 

Researchers from The Hebrew University of Jerusalem in Israel have reported the fabrication of flexible and semitransparent perovskite-based solar cells.

Much of the research in the field of building-integrated photovoltaics is focused on semitransparent perovskite solar cells on glass substrates, which can be utilized as glass windows during the construction of the buildings. In their recent study, the team chose to develop cells that can be used in existing windows through a retrofitting process.

Scientists from the University of Konstanz in Germany, Quaid-i-Azam University and Kohsar University Murree in Pakistan and Huazhong University of Science and Technology in China have fabricated an inverted perovskite solar cell with a passivation technique utilizing a mixed solvent vapor annealing method based on ethylenediamine (EDA).

The team managed to show how simple passivation can improve both the performance and operational stability of a perovskite solar cell. The scientists said EDA has been used in previous research projects to suppress the defect states in different kinds of perovskite. However, the exact way that EDA contributes to the morphology, defect passivation and optoelectronic properties of perovskite films was unclear.