A group of scientists from Germany's Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE), with support from Oxford PV Germany, have examined shingling as an interconnection method for perovskite-silicon tandem (PVST) cells.

Full-format perovskite-silicon tandem shingle modules produced at Fraunhofer ISE in collaboration with Oxford PV. Image from Solar Energy Materials and Solar Cells.

The scientists explained that the combination of PVST cells with shingling allows boosting the module efficiency even further due to the increase of the photoactive area through the absence of cell gaps. They went on to say that shingling suits the temperature limitations of the PVST cells since the main factor for the choice of the processing temperature is the curing conditions of the electrically conductive adhesive.

Existing fabrication processes for creating efficient metal halide perovskite solar cells (PSCs) require an inert (i.e., chemically inactive) atmosphere, such as that within a nitrogen glovebox. Recently, researchers from China's North China Electric Power University have introduced a strategy to create PSCs with PCEs above 25% in ambient air. 

This strategy is hoped to accelerate commercialization of PSCs. "The fabrication of perovskite solar cells (PSCs) in ambient air can accelerate their industrialization," Luyao Yan, Hao Huang and their colleagues wrote in their paper. "However, moisture induces severe decomposition of the perovskite layer, limiting the device efficiency. We show that sites near vacancy defects absorb water molecules and trigger the hydration of the perovskite, eventually leading to the degradation of the material." To fabricate their solar cells in ambient air conditions, the scientists blocked the pathway through which perovskite layers can become hydrated and consequently suffer severe damage. They did this using the acetate salt form of the chemical compound guanabenz, known as GBA.

Researchers at the Indian Institute of Technology Mandi (IIT-Mandi), the National Institute of Solar Energy (NISE) and China's Guangxi University have designed efficient indoor bifacial perovskite photovoltaics (i-BPPVs) with the capability of harvesting maximum light from both top and bottom sides. This achievement could be a significant step towards advancing cost-effective and efficient technology for harvesting more energy from artificial indoor light sources.

The i-BPPVs were designed and fabricated in a stack of organic–inorganic hybrid perovskite material amid a transparent bottom electrode (ITO), and top (Au/ITO) electrode. The fabricated i-BPPVs exhibited an efficiency of 30.3%, short circuit current density (JSC) of 148.3 µA cm⁻², open circuit voltage (VOC) of 0.93 V, and fill factor (FF) of 71.7% when artificial LED light source of 1000 lx is exposed from the top side, whereas an efficiency of 22.1%, JSC of 116.2 µA cm⁻², VOC of 0.89 V, and FF of 69.4% have been obtained from the bottom side. 

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Oxford PV has announced that its perovskite-on-silicon tandem solar cells will be deployed for the first time on the race car of the Top Dutch Solar Racing team for the upcoming Bridgestone World Solar Challenge. 

Taking place between the 22nd and 29th of October 2023, the competition brings some of the world’s greatest scientific and engineering talent to Australia to travel 3,000 kilometers in a vehicle powered only by the energy of the sun. University-affiliated teams push the limits of technological innovation and travel the outback in solar-powered vehicles that they have designed, engineered and ultimately built themselves.

Researchers from the University of Warsaw and the Fraunhofer Institute for Solar Energy Systems ISE have examined the question of whether or not nano-scale surface texturing, used on some silicon cells, can be applied to perovskite cells instead of more commonly used planar magnesium fluoride anti-reflection coatings.   

a) the scheme of the perovskite solar cell sample before any top surface modification and after the application of either MgF2 layer or honeycomb texture application, b) device photography with four active cell areas after imprinting the honeycomb texture. Image from Advanced Materials and Interfaces

“To minimize losses, silicon cells are typically etched with corrosive chemical agents, a process that creates microscopic pyramid pattern on the surface, effectively reducing reflection,” said the scientists. “Unfortunately, perovskites are sensitive to many chemical substances, which is why less effective planar anti-reflective coatings [planar MgF₂] applied through less-invasive sputtering have been employed so far.”

Japanese Prime Minister, Fumio Kishida, has announced the government’s plan to commercialize “perovskite-type” solar panels by 2025.

Kishida made the announcement at a meeting with corporate executives at the Prime Minister’s Office in Tokyo. He said the government would compile an “investment strategy for green transformation by the end of the year to develop and promote technologies and products that are critical to achieving carbon neutrality,” including the development of perovskite solar cells.

Researchers from Southeast University and the University of Liberal Arts Bangladesh have designed and simulated an all-inorganic lead-free tandem photovoltaic cell based on copper, indium, gallium and selenium (CIGS) thin-film technology and perovskite.

The proposed top cell (a) and bottom cell (b), image from Heliyon

The novel device architecture is said to have the potential to reach a power conversion efficiency of 38.39%. “The main objective of this work is to find an efficient combination of non-toxic solar cells with high efficiency so that it saves time and effort before going for fabrication,” the scientists said in their work, noting that the perovskite and materials used for the cell are lead-free.

Toray Research Centre (TRC) has been developing cutting-edge perovskite solar cells analysis services since 2014. The company can perform a wide range of measurements and tests, on a wide range of perovskite panel types, without atmospheric exposure, at the company’s state-of-the-art facilities.

TRC’s highly skilled technical team recently published five technical white papers, each showcasing perovskite analysis results. You are welcome to access these white papers by signing up here.

• Evaluation of electrical characteristics and crystalline in perovskite solar cells: TRC evaluated to surface roughness and the distribution of spreading resistance near the surface by SSRM. The result showed that the regions of high spreading resistance on the surface of the PVK layer increase with heat treatment. TRC also performed ACOM-TEM analysis and it revealed a decrease in PVK phase and particle size, and an increase in PhI2 phase with heat treatment.
• Surface analysis of power generation layer for Perovskite Solar Cells: X-ray diffraction (XRD), SEM (Secondary Electron Microscopy), and SSRM (Scanning Spread Resistance Microscopy) can evaluate the crystal structure, the form of the surface, the distribution of element, and spread resistance.
• Evolved gas analysis by TPD-MS and depth profile analysis by SIMS of perovskite solar cells: To improve the heat treatment during the perovskite solar panel production process, it is important to understand the decomposed gases from the material and the composition distribution in the material. In this paper, TRC shows the evaluation results of evolved gases during heating by TPD-MS and the elemental distribution in the depth direction by GCIB-TOF-SIMS and Dynamic-SIMS
• Depth profile analysis to element and organic matter of Perovskite Solar Cell: Cross-sectional TEM, Dynamic-SIMS(D-SIMS) and GCIB-TOF-SIMS can be performed the distribution of element and organic matter with high spatial resolution and high sensitivity under non-exposed atmospheres. These processes are very helpful for the improvement of process, materials and devices of PSC
• Composition and impurity analysis of light absorbers of perovskite-based solar cells: It is important to figure out the concentration of composition and impurity of light absorbers to achieve high efficiency in perovskite-based solar cells. For the analysis of inorganic elements, ICP-AES, ICP-MS and ion chromatography are available.

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Researchers from the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) and Oxford PV Germany have developed low temperature manufacturing processes for perovskite silicon tandem cells and heterojunction solar cells. The novel techniques are reportedly able to reduce silver consumption and avoid lead-containing soldering materials.

The scientists developed two different processes: front-side metallization at very low temperatures for full-size perovskite silicon tandem solar cells; and the interconnection to high-efficiency full-format demonstrator modules with an output power of more than 400 W.