Efficiency - Page 15

Researchers from Japan's University of Electro-Communication and CAR MATE MFG. CO. have developed a lead-free tin sulfide solar cell that is intended for applications in tandem perovskite-silicon PV devices. 

Using a new passivation technique based on the use of phenylsilane (PhSiH₃) as a reducing agent, the scientists were able to considerably increase the cell's efficiency compared to a reference device with no PhSiH₃ treatment.

Researchers from China's Shanghai University of Engineering Science have developed a novel solar spectral converter using a GdPO₄ glass-ceramic (GC) material doped with praseodymium (Pr) and europium (Eu) ions. This technology could lead to notable boosts in performance and applicability of solar cells.

The main purpose of GdPO₄-GC:Eu³⁺/Pr³⁺ is to absorb UV photons from solar radiation and re-emit them as visible light. This is possible thanks to the efficient energy transfer that happens between the ions in the material.

In 2022, publicly traded footwear producer and solar technology maker Golden Solar, based in China, signed an agreement with two partners to pursue commercial production of perovskite tandem solar cells with 'more than 28%' conversion efficiency. Now, Golden Solar New Energy Technology Holdings Limited has announced the launch of its perovskite/hybrid BC Tandem Solar Cells.

Golden Solar stated that it will apply 'the world's most advanced battery technology to C-end products, gradually develop a series of ultra-high-efficiency C-end products, and open up a broader space for growth'. Recently, the first perovskite/hybrid BC four-terminal tandem solar cell was launched, claimed to have a conversion efficiency of 33.94%.

Perovskite/perovskite/silicon triple-junction cells can deliver higher efficiencies than single- or dual-junction solar cells, but achieving this is not without its challenges. In a recent study, researchers from King Abdullah University of Science and Technology (KAUST), Northwestern University, University of Toledo and University of Toronto combined with a synergistic additive strategy (using potassium thiocyanate and methylammonium iodide), to stabilize the top perovskite, thus addressing a major hurdle. The team fabricated a perovskite-perovskite-silicon triple-junction solar cell with a new passivation strategy based on the utilization of potassium and thiocyanate.

This approach leads to an efficiency of over 26% for 1 cm² triple-junction solar cells. The triple-junction solar cell is based on a 15.0%-efficient top perovskite solar cell modified with potassium thiocyanate (KSCN) and methylammonium iodide (MAI). According to the team, the triple-junction device displays a remarkable power conversion efficiency improvement compared to state-of-the-art devices.

Researchers from China's Qingdao University of Science and Technology, Beijing Huairou Laboratory and the Chinese Academy of Sciences have developed an additive with a conjugated structure, 2,2′-diamino-[1,1′-biphenyl]-4,4′-dicarboxylic acid (DBDA), containing amino and carboxyl groups. The additive was introduced to convert tensile strain to compressive strain in perovskite films. 

Lattice tensile strain generated during the preparation of perovskite thin films has detrimental effects on the efficiency and stability of perovskite solar cells (PSCs). The scientists in this work examined this additive as a way to mitigate these harmful effects.

Researchers at Germany's Forschungszentrum Jülich have reported a method to fabricate >1-micrometer thick perovskite films by employing hole-transporting bilayers of self-assembled monolayers (SAMs) and poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine] (PTAA). Recognizing the critical role transport layers play in exacerbating thickness-dependent losses, the team optimized a dual-layer hole transport architecture to reduce resistive losses and recombination. The authors achieved remarkable efficiency retention at over 1 micron thickness.

This work focuses on a solar cell architecture that decouples thickness from efficiency limitations. By sandwiching specialty organic films around the perovskite layer, the authors enabled micron-scale thicknesses without forfeiting peak performance. Their design notably achieves a remarkable 20.2% efficiency at over 1 micron thickness with minimal losses compared to thinner versions.

The CEA at INES, ENEL Green Power and its Sicilian affiliate 3SUN have announced a new record for a PIN architecture two-terminal perovskite-silicon tandem cell with a conversion efficiency of 28.4% on 9 cm² with shading correction.

In 2023, the CEA and 3SUN have previously announced 26.5% in March, and 27.1% in June for the same type of PIN architecture tandem cell on 9cm² with shading correction. The year closes on a high note for the team, with this cell, certified by the European Commission JRC-ESTI at a conversion efficiency 24.4% equivalent to 28.4% with shading correction. Like the previous performance record, the device has an active surface area of ~ 9 cm² and a Voc of over 1900 mV.

Researchers at China's Wuhan University of Technology, Huazhong University of Science and Technology and Jinan Municipal Bureau of Industry and Information Technology have developed a novel playdough-like graphite putty as top electrode for perovskite solar devices. The electrode is malleable and so can form good contact with the hole-transporting layer and the conductive substrate at room temperature using a simple pressing technique, which facilitates the fabrication of both small-area devices and perovskite solar modules. 

Carbon-based perovskite solar cells (C-PSCs) are promising candidates for large-scale photovoltaic applications due to their theoretical low cost and high stability. However, the fabrication of high-performance C-PSCs with large-area electrodes remains challenging. In their recent research, the team showed that corresponding small devices and modules can achieve efficiencies of 20.29% (∼0.15 cm²) and 16.01% (∼10 cm²), respectively. Moreover, they analyzed the limitations of the optical and electrical properties of this playdough-like graphite electrode on the device performance, suggesting a direction for further improvement of C-PSCs in the future.

Researchers at South Korea’s Chonnam National University have reported perovskite-organic hybrid tandem solar cells with 23.07% efficiency processed entirely in open air, bringing the technology a step closer to economic viability.

Schematic illustration of the synthesis of all-inorganic perovskite thin films by dynamic hot-air-assisted method. Image from Energy & Environmental Science 

Researchers have largely relied on meticulously engineering the perovskite crystal structure itself for greater resilience. But these delicate handling steps add cost and complexity not suitable for mass production. The team explained that the focus has recently shifted toward all-solution processed solar cells due to their low energy consumption fabrication processes. The team’s innovation, a dynamic hot air deposition technique, simplified the production process by eliminating the need for humidity-controlled environments.

Researchers at Germany’s Fraunhofer ISE have estimated that the practical power conversion efficiency potential of perovskite-silicon tandem solar cells may reach up to 39.5%. In a recent study, the Fraunhofer ISE scientists set out to provide guidelines for future research on perovskite-silicon tandem solar cells by identifying the most significant loss mechanisms at the perovskite/ETL interface, in the series resistance, and in light management.

The team explained that the calculated practical efficiency potential of 39.5% for a perovskite silicon tandem device under standard measurement conditions (STC) can serve as an input for future studies which are required for a better understanding of the full system before the commercialization of tandem solar cell technology can take place.