Efficiency - Page 5

BusinessKorea reports that researchers at the Ulsan National Institute of Science and Technology (UNIST) have significantly improved the efficiency and stability of perovskite solar cells by addressing defect issues.

Schematic of perovskite crystallinity changes and thickness-based photoluminescence analysis through the introduction of bidirectional tuning molecules. Source: BusinessKorea, UNIST

The UNIST team announced that a joint research team, led by Professors Kim Jin-young and Kim Dong-seok from the Department of Energy and Chemical Engineering, and Professor Lee Geun-sik from the Department of Chemistry, successfully introduced bidirectional tuning molecules between the perovskite photoactive layer and the electron transport layer.

An international team of researchers, including ones from the University of Toronto, University of Toledo, Northwestern University, Lawrence Berkeley National Laboratory, KAUST and more, recently developed an all-perovskite tandem device that is said to show reduced recombination losses in the cell’s bottom device and excellent stability.

Image credit: Northwestern University
 

To improve the perovskite solar cell’s surface, the scientists created partially non-conductive and non-functional areas that protect the perovskite area underneath from becoming defective. The team examined the addition of diamine to improve the perovskite solar cell’s surface. The scientists found that the process made the surface more stable and improved the overall performance, resulting in a power conversion efficiency of 27.4% with better stability.

Researchers from China's Beijing Institute of Technology, Peking University, Central South University, Jiangnan University and Auner Technology have developed a unique binary 2D perovskite passivation approach and used it to fabricate a monolithic perovskite/silicon tandem solar cell with a steady-state efficiency of 30.65% (reportedly assessed by a third party). 

Schematic of the monolithic tandem structure based on a double-side textured silicon heterojunction cell. Image credit: Nature Communications

The tandem devices also retained 96% of their initial efficiency after 527 h of operation under full spectral continuous illumination, and 98% after 1000 h of damp-heat testing (85 °C with 85% relative humidity).

Researchers from China's Jinan University, University of Macau, Wuyi University, Guangdong Mellow Energy and Germany's IEK-5 Photovoltaik (Forschungszentrum Jülich) recently designed a two-terminal perovskite-silicon tandem solar cell that utilizes new hybrid interconnecting layers to reduce recombination losses in the top perovskite device. The tandem cell achieved an impressive fill factor of 81.8%, which the scientists said is the highest value ever reported for this cell technology to date.

The team's 2T perovskite-silicon tandem solar cell is based on special hybrid interconnecting layers (ICLs) that prevent direct contact between the perovskite absorber and transparent conductive oxide (TCO). The scientists' approach is based on sputtered nickel oxide (NiOx) as the seed layer of SAMs to build the hybrid interconnecting layers. The sputtered treatment technique provides, according to the team, an easy coating on a complex substrate and high reproducibility.

Researchers from the Chinese Academy of Sciences (CAS) posit that the efficiency and stability of perovskite modules are mainly limited by the quality of scalable perovskite films and sub-cells’ lateral contact. So, in their recent work, they addressed this by reporting constant low temperature substrates to regulate the growth of perovskite intermediate films to slow down the crystallization process. This is meant to assist in obtaining high-quality homogeneous perovskite films in large scale size, which avoid the effect of the ambient temperature on the film quality. 

Schematic diagram of the fabrication process of perovskite films using low-temperature substrate growth (LTSG). Image from Nature Communications

In addition, a scribing step named P1.5 was added before the top function layers deposition, so the diffusion barrier layer can be formed “naturally” at the interconnection interface without introducing any additional materials, which alleviates the diffusion degradation process. 

Researchers from Pakistan's University of Agriculture Faisalabad, University College of London United Kingdom and The National University of Malaysia have conducted a series of simulations to investigate how a cadmium telluride buffer layer (BL) may help increase efficiency and stability in perovskite solar cells. Their experiment showed that cell efficiency may climb from 11.09% to 23.56%.

Solar cell architecture with BL. Image credit: Results in Engineering

The researchers explained that the presence of a BL in a perovskite cell offers a porous structure that aids in forming the upper hole-transporting layer (HTL), while also preventing the leakage of corrosive additives from the HTL material. “The improvement in the development of HTM layer not only promotes efficient hole transfer and conduction but also restricts charge recombination,” they explained.

SolaEon Technology, a Chinese solar manufacturer, claims that it has achieved a record conversion efficiency of 21.95% on 300mm x 400mm monolithic perovskite tandem solar cells for MPPT.

In October 2023, SolaEon claimed its 1,200 sq. cm. perovskite single-junction solar cell module achieved a 3rd party certified efficiency of 21.63%. In April 2024, SolaEon said its perovskite solar cell module achieved a steady state efficiency of 19.2% based on 1,027.1 c㎡ area. In May 2024, it reportedly achieved a world record conversion efficiency of 29.34% for monolithic full perovskite tandem solar cells. 

A research team at City University of Hong Kong (CityUHK) has announced a new generation of printable perovskite solar cells that offer higher efficiency and stability, lower cost and scalability, with a minimal carbon footprint. With funding support from the inaugural Research, Academic and Industry Sectors One-plus Scheme (RAISe+ Scheme) of the Innovation and Technology Commission of the HKSAR government, the team aims to establish a pilot production line within 18 months.

The “Scalable Production of Next-Generation High-Performance Printable Solar Cells” project, led by Professor Alex Jen at CityUHK, was awarded RAISe+ funding to commercialize the technology. Professor Jen is a pioneer in developing perovskite solar cells that has achieved, along with his research team at CityUHK, significant milestones in recent years - such as perovskite solar cells that displayed a power conversion efficiency of over 26% in laboratory testing. They also successfully addressed the common stability issues by demonstrating perovskite solar cells with an estimated lifetime of over 20 years through accelerated aging tests, comparable to that of silicon-based cells in the market.

Integrating metal-halide perovskites with the industrially textured Czochralski silicon for perovskite/silicon tandem cells shows great promise for low-cost manufacturing and ideal light trapping. However, the conformal growth of high-quality perovskite film on fully textured silicon remains challenging due to the lack of effective regulation of structural evolution and residual strains. 

Recently, researchers from Nanchang University, Suzhou Maxwell Technologies, The Hong Kong Polytechnic University, CNPC Tubular Goods Research Institute, Henan Normal University, Southern University of Science and Technology, Chinese Academy of Sciences, City University of Hong Kong, Yunnan University, Harbin Institute of Technology (Shenzhen) and Fudan University reported a strain regulation strategy by forming a 3D/3D perovskite heterojunction at the buried interface through a vacuum-deposition method applicable to pyramidal texture. They found that the strained heterojunction enables high-performance, fully textured perovskite/silicon tandem solar cells that achieve an efficiency of up to 31.5%.

Researchers from King Abdullah University of Science and Technology (KAUST) and Marmara University set out to minimize crystal defects and film inhomogeneities in perovskite top cells, to achieve the full potential of monolithic perovskite/silicon tandem solar cells. 

In their recent work, the scientists discuss the use of methylenediammonium dichloride as an additive to the perovskite precursor solution, resulting in the incorporation of in situ–formed tetrahydrotriazinium (THTZ-H⁺) into the perovskite lattice upon film crystallization.