Efficiency

Hanwha Solutions Qcells Division (Hanwha Qcells), a global leader in complete clean energy solutions, has announced a new world record, reaching 28.6% for tandem solar cell efficiency on a full-area M10-sized cell that can be scaled for mass manufacturing. This result was achieved despite having only begun large-area tandem development in 2023.

“The tandem cell technology developed at Hanwha Qcells will accelerate the commercialization process of this technology and, ultimately, deliver a great leap forward in photovoltaic performance,” said Danielle Merfeld, Global CTO at Hanwha Qcells. “We are committed to advancing the next generation of solar energy efficiency and will keep investing significantly in research and development to drive progress in this field, as every kilowatt counts on the path to building a more sustainable future.”  

Nexwafe, a German wafer manufacturer, said that a perovskite-silicon tandem solar cell it developed in partnership with the Swiss Center for Electronics and Microtechnology (CSEM) has achieved a power conversion efficiency of 28.9%.

The tandem perovskite 2-junction cells used NexWafe’s EpiNex wafers and demonstrated their potential for advanced solar technologies. The company stated that with superior smoothness at the nano-scale, EpiNex wafers provide the ideal platform for the next generation of low-cost, solution-processed tandem perovskite cells.

In November 29, Hangzhou Xianna Optoelectronic Technology Co., Ltd. delivered its perovskite α-tandem modules for the China Three Gorges New Energy 50 MW PV demonstration project, in what is said to mark the first commercial application of four-terminal perovskite-silicon tandem modules in China. 

Once the PV power plant utilizing these tandem modules is completed and connected to the local grid, it will significantly alleviate the local grid's supply-demand imbalance, reduce environmental pollution, and improve air quality. The design work for a 500 kW demonstration plant has already been completed, with plans to collaborate with engineering institutes for on-site module layout design. The demonstration plant is expected to be connected to the grid and operational by the end of 2024.

Researchers from China's Tianjin University of Technology, Zhejiang Sci-Tech University, University of Electronic Science and Technology of China, North China Electric Power University and South China University of Technology have shown that the introduction of azetidinium iodide (AZI) into the precursor solution of a 1.77 eV bandgap FA_0.8Cs_0.2Pb(I_0.6Br_0.4)₃ perovskite significantly improves the efficiency and stability of the perovskite cells. 

Devices fabricated with 2 mol% AZI (relative to FAI, noted as AZ2) in perovskite layer exhibited a high PCE of 19.16 % and a high open-circuit voltage of 1.31 V. When stored under nitrogen atmosphere and illuminated under 1 sun conditions for 300 h, AZ2 device retained 80 % of the initial values. 

According to reports, China Huaneng (China Huaneng Group Co., Ltd.) has achieved a power conversion efficiency of 26.12% on its self-developed large-size perovskite silicon tandem cell, and the result was certified by a third-party testing institution.

China Huaneng stated that after more than ten years of research, it has established a systematic platform for R&D, pilot testing and analysis of perovskite cells, mastered the technology of large-area high-efficiency perovskite and tandem solar modules, and taken the lead in the application of perovskite photovoltaic technology, carried out the verification of kilowatt-scale solar systems using perovskite modules in various scenarios, and built the first megawatt-scale solar system using large-scale perovskite products in overseas.

Researchers from Huaqiao University, Gold Stone (Fujian) Energy Company, Beijing Huairou Laboratory and Kunshan Shengcheng Photoelectric Technology have reported a four-terminal (4T) perovskite-silicon solar cell with a perovskite-based top cell, with an energy bandgap of 1.67 and lower surface defects. 

Structure of the 4T perovskite/silicon tandem solar cells. Image from Nature Communications

The team integrated a wide-bandgap perovskite solar cell with a hybrid back contact device in a four-terminal tandem cell that achieves high efficiency and stability. The group used a new surface passivation strategy that reportedly helped gain the cell's strong performance.

Over the past five years, six Fraunhofer Institutes combined their expertise in the Fraunhofer lighthouse project "MaNiTU" to identify the most sustainable paths to market of perovskite-silicon tandem solar cells made of stable materials and manufactured using scalable production processes. They were able to show that high cell efficiencies can be achieved using industry-oriented processes, however, they found that such high efficiencies were only currently achievable with lead perovskite materials. Based on these findings, the researchers developed suitable recycling concepts to ensure sustainability.

In the "MaNiTU" project, the Fraunhofer researchers produced new materials with perovskite crystal structures and compared them with existing materials at the cell level. The comparisons showed that high efficiencies can only be achieved with lead perovskites. They then successfully fabricated highly efficient demonstrators, for example, a perovskite silicon tandem solar cell of more than 100 square centimeters with screen-printed metallization and produced mini modules for single and interconnected tandem solar cells. Subsequent life cycle analyses showed that by using suitable production and recycling processes and degradation rates comparable to today's silicon technology, it is feasible to make a sustainable product.

An international team of researchers from Bangladesh, USA and Saudi Arabia recently developed a structure that combines a double perovskite absorber layer (DPAL) of Ca₃NCl₃ and Ca₃SbI₃ with an electron transport layer (ETL) and hole transport layer (HTL) of CdS and CBTS via SCAPS-1D. 

The team's research demonstrated that the perovskite solar cell (PSC) with DPAL performs much better with the addition of HTL and is more efficient than single-layer PSCs. This work thoroughly examines the effect of thickness, doping levels, and defect densities of each layer on electrical parameters like VOC, JSC, FF, and PCE. 

It was reported that China-based Microquanta has shipped its self-developed 50 MW perovskite α modules to China Huaneng for a PV demonstration project, reportedly marking China’s first commercial use of four-terminal perovskite-silicon tandem modules. 

The 1,245 mm x 635 mm modules feature perovskite layers on tunnel oxide passivated contact (TOPCon) cells, achieving a power conversion efficiency of 25.4%.

As it currently remains challenging to obtain precise control over the formation of the thin 2D layer used in 2D/3D heterojunction perovskite solar cells, researchers from China's Jinan University set out to design a method for the precise preparation of 2D/3D perovskite heterojunctions.

Using their new method, the team constructed two different 2D/3D heterojunctions using a vapor-solution mixed deposition method and compared them with heterojunctions formed via conventional solution methods, achieving a PCE of the device from 20.67 % to 22.68%. The new strategy could be a useful way to optimize perovskite films and advance the fabrication of high-efficiency perovskite solar cells.