Technical / research - Page 21

Researchers at the University of Michigan and Arizona State University have examined bulky "defect pacifying" molecules as a way to increase the stability and overall lifespan of perovskite materials.

The team expects this novel way of preventing perovskite materials from degrading quickly could help enable solar cells estimated to be two to four times cheaper than today's thin-film solar panels.

Researchers at China's Sun Yat-sen University, Spain's Universidad de Valencia, Germany's Forschungszentrum Jülich, and University of Duisburg-Essen have used transient photoluminescence measurements to show that the loss of charge carriers in perovskite cells follows different physical laws than those known for most semiconductors. This may be one of the main reasons for their high level of efficiency. 

“An important factor here is the question of how long excited charge carriers remain in the material, in other words their lifetime,” explains Thomas Kirchartz. “Understanding the processes is crucial to further improving the efficiency of perovskite-based solar cells”. Kirchartz is the head of a working group on organic and hybrid solar cells at Forschungszentrum Jülich’s Institute of Energy and Climate Research (IEK-5).

Researchers at the Chinese Academy of Sciences (CAS), Shanghai Jiao Tong University School of Medicine and the University of Electronic Science and Technology of China (UESTC) have presented a simple and economical encapsulation strategy with shellac to protect perovskite solar cells (PSCs) under various accelerated degradation experiments. 

The shellac-encapsulated (SE) PSC modules reportedly passed outdoor stability, UV preconditioning, and hail tests according to the International Electrotechnical Commission 61215 standard (IEC61215). 

Electronic band structure engineering of metal-halide perovskites (MHP) is at the heart of fundamental materials research and photovoltaic applications. However, reconfiguring the band structures in MHPs for optimized electronic properties remains challenging. Researchers at Wuhan University have reported a generic strategy for constructing near-edge states to improve carrier properties, leading to enhanced device performances. 

The near-edge states are designed around the valence band edge using theoretical prediction and constructed through tailored material engineering. These states are experimentally revealed with activation energies of around 23 milli-electron volts by temperature-dependent time-resolved spectroscopy. 

Researchers from the Daegu-Gyeongbuk Institute of Science and Technology (DGIST) in South Korea have developed silver-alloyed CIGS solar cells (ACIGS) that can be beneficial for applications in perovskite-CIGS tandem PV devices. 

The silver-alloyed photovoltaic cell based on copper, indium, gallium and selenium (CIGS) thin-film technology and can reach a remarkable power conversion efficiency of 17.7% without applying post-deposition treatments or anti-reflection coatings. 

Both ferromagnetic and ferroelectric materials are widely used today, and can coexist together in so-called multiferroic compounds, which can be traced back to the 1950s. Their use in modern technology has seen a recent resurgence as multiferroic compounds are energy-efficient and could be used in information storage devices for computers, servers, and hard drives.

Working with researchers from Kyoto University in Japan, Northwestern Engineering’s James Rondinelli discovered the first all-inorganic halide perovskite-derived multiferroic material, exhibiting a form of ferroelectricity called hybrid improper ferroelectricity which is also coupled to magnetic properties. In the past, studies of multiferroic compounds had been largely limited to transition metal oxides, yet many other materials classes can exhibit this phenomenon.

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.

A collaborative team of researchers, including ones from Uppsala University, CNR-SCITEC, Fraunhofer ISE, University of Cambridge, Empa, EPFL and additional institutes, recently introduced an unexplored dimethylphenethylsulfonium iodide (DMPESI) molecule to post-treat formamidinium lead iodide perovskite films. The treated films showed outstanding stability upon light soaking and remarkably remains in black-phase after 2 years ageing under ambient condition without encapsulation. 

Fresh and 24-month aged unencapsulated perovskite film (1.0 cm by 2.0 cm) without and with DMPESI treatment of different concentrations. Image from Nature Energy

The DMPESI-treated PSCs deliver a breakthrough record in operational stability of highly-efficient PSCs with less than 1% performance loss after more than 4500 h at maximum power point tracking, yielding an extraordinarily high theoretical T80 of over 9 years under continuous 1-sun illumination, which would correspond to a photon flux of an outdoor PV installation in Sweden or Germany (1,000 kWh m−2 per year) of over 78 years. 

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.

Researchers at Pusan National University and the University of Oxford have made an advanced in the field of perovskite nanosheets as promising new laser materials. The team overcame the inherent limitations of CsPbBr quantum dots using perovskite nanosheets, which provide enhanced light amplification abilities. 

The researchers introduced an innovative waveguide pattern, which increased the gain and thermal stability of the perovskite nanosheets. This pattern improved the optical confinement and heat dissipation, offering a solution to the limitations previously faced with quantum dots. The research team also pioneered a new ‘gain analysis’ method known as the ‘gain contour’. This novel technique provides a more in-depth understanding of gain saturation across various spectrum energies and optical stripe lengths.