Reports suggest that LONGi Green Energy Technology managed to reach a conversion efficiency of 33.9% for its silicon-perovskite tandem solar cells.
The result, currently the highest efficiency record in the world for a perovskite/silicon tandem cell, has reportedly been confirmed by the US National Renewable Energy Laboratory (NREL).
An international team that included scientists from the Chinese Academy of Sciences (CAS), Southern University of Science and Technology (SUSTech), University of Science and Technology of China (USTC), Sungkyunkwan University (SKKU), The Hong Kong University of Science and Technology, University Grenoble-Alpes, CEA, CNRS, INP, IRIG/SyMMES, IEK5-Photovoltaics and North China Electric Power University (NCEPU), has proposed a new method of fabricating homogenized perovskite films for solar cells.
The process involves inhibiting phase segregation caused by internal cation inhomogeneity to increase conversion efficiency to 26.1%, thus tying the existing record.
Researchers at Empa, National University of Singapore (NUS) and Helmholtz Institute Erlangen-Nürnberg for Renewable Energy HI ERN have reported novel electrical and optical enhancement approaches to maximize the performance of perovskite front cells.
The team introduced new electrical and optical techniques, using methyldiammonium diiodide and adjusting the optical interference spectrum. This resulted in a record efficiency of 20.2% (21.8% by J-V scan) for a semi-transparent perovskite cell and 81.5% average near-infrared transmittance.
Researchers from the University of Rome Tor Vergata, ENEA and CNR-ISM have used protective buffer layers in perovskite solar cells to mitigate damage during the sputtering of indium tin oxide in the production process. The scientists claim the buffer layers were able to achieve this without damaging the cell’s average visible transmittance.
The cell utilizes buffer layers made of transition metal oxides (TMOs) intended to protect the cell during the sputtering of indium tin oxide (ITO) in the cell production process. The scientists tested, in particular, two different evaporated transition metal oxides (TMOs) – molybdenum oxide (MoOx) and vanadium oxide (V2Ox) and found the former provided the best performance.
Inverted perovskite solar cells (PSCs) can deliver enhanced operating stability compared to their 'normal'-structure counterparts. To improve efficiency further, it is vital to combine effective light management with low interfacial losses. Now, scientists at Northwestern University, University of Kentucky, North Carolina State University, University of Toronto, Ecole Polytechnique Fédérale de Lausanne (EPFL) and Peking University have developed a conformal self-assembled monolayer (SAM) as the hole-selective contact on light-managing textured substrates.
The team reported that molecular dynamics simulations indicate cluster formation during phosphonic acid adsorption leads to incomplete SAM coverage. They devised a co-adsorbent strategy that disassembles high-order clusters, thus homogenizing the distribution of phosphonic acid molecules, thereby minimizing interfacial recombination and improving electronic structures.
In an effort to tackle the challenge of perovskite solar cells' thermal instability, researchers at City University of Hong Kong (CityU), National Renewable Energy Laboratory (NREL) and Huazhong University of Science and Technology have developed a unique type of self-assembled monolayer, or SAM for short, and anchored it on a nickel oxide nanoparticles surface as a charge extraction layer. This method dramatically enhanced the thermal robustness of perovskite solar cells, according to Professor Zhu Zonglong of the Department of Chemistry at CityU.
“By introducing a thermally robust charge extraction layer, our improved cells retain over 90% of their efficiency, boasting an impressive efficiency rate of 25.6%, even after operated under high temperatures, around (65℃) for over 1,000 hours. This is a milestone achievement,” said Professor Zhu.
Researchers at the University of North Carolina at Chapel Hill and Arizona State University and have designed a large-area perovskite-silicon tandem solar cell that achieved a steady-state power conversion efficiency of 25.1% for tandem devices with a large aperture area of 24 cm2.
The team set out to overcome shunting, which is a common issue when scaling up perovskite solar technologies from small-area cells to large-area devices. “Shunts” in PV cells create alternate pathways for a solar-generated charge, leading to power losses. Reduced shunt resistance is associated with multiple forms of module degradation and failure, including hotspots and potential-induced degradation.
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.
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.
