Technical / research - Page 28

Researchers from Gwangju Institute of Science and Technology (GIST), Korea Research Institute of Chemical Technology (KRICT) and Lawrence Berkeley National Laboratory have developed a highly efficient organometal halide perovskites (OHP)-based photoanode using a rational design approach, which addresses current limitations.

Currently, hydrogen is mainly produced by natural gas, which also generates greenhouse gases such as carbon dioxide as by-products. It is argued that hydrogen produced this way, while economical, is not truly sustainable, and thus requires a more eco-friendly approach for its generation. Photoelectrochemical (PEC) water splitting based on solar energy is one such promising approach. However, its widespread application is limited by a lack of efficient photoanodes for catalyzing the rate-limiting oxygen evolution reaction (OER), an important reaction in PEC water splitting. Organometal halide perovskites (OHPs) have emerged as a promising photoanode material on this front. Unfortunately, OHP-based photoanodes suffer from two undesired losses that limit their efficiency. One is an internal loss resulting from a recombination of photogenerated charge carriers (required for electricity generation) within the anode itself, which, in turn, hinders water splitting. The other is external loss due to the slow reaction kinetics of water splitting, resulting in a loss of charge carriers at the interface of the anode and electrolyte. These are the challenges tackled by the team in this recent work.

Researchers from Washington University in St. Louis and  Florida State University have developed a versatile, scalable and eco-friendly handwriting approach to draw multicolor perovskite light-emitting diodes and perovskite photodetectors on various substrates, including paper, textiles, plastics, elastomers, rubber and three-dimensional objects. 

The team's method uses common ballpoint pens filled with newly formulated inks of conductive polymers, metal nanowires and multiple perovskites for a wide range of emission colors. Just like writing with multicolored pens, writing layer-by-layer with these functional inks enables perovskite optoelectronic devices to be realized within minutes.

Researchers from China's Westlake University, Zhejiang University, Binzhou University and U.S-based Purdue University have reported the synthesis of a series of 2D tin perovskite bulk crystals with high phase purity via a mixed-solvent strategy. 

Ruddlesden-Popper tin halide perovskites are a class of two-dimensional (2D) semiconductors with exceptional optoelectronic properties, high carrier mobility, and low toxicity. However, the team aimed to address the issue of their challenging synthesis and the lack of fundamental understanding of their optoelectronic properties (compared to their lead counterparts). 

Researchers from Zhengzhou University and the Chinese Academy of Sciences (CAS) have devised a novel lead capturing technique for perovskite solar cells: they implanted a multifunctional mesoporous amino-grafted-carbon net into the perovskite solar cells, creating biomimetic cage traps that could effectively mitigate Pb leakage and shield from external invasion under extreme weather conditions. 

The team then explored the synergistic Pb capturing mechanism in terms of chemical chelation and physical adsorption. Additionally, the Pb contamination assessment of end-of-life perovskite solar cells in the real-world ecosystem, including Yellow River water and soil, was proposed by the scientists. 

Researchers from Stanford University and Mississippi State University recently explored the potential of Mn²⁺-doped perovskite LEDs (PeLEDs) for lighting and display applications. 

By introducing a molecular additive, tris(4-fluorphenyl)phosphine oxide (TFPPO), Mn²⁺-doped PeLEDs achieved a peak external quantum efficiency of 14.0% and peak luminance (i.e., brightness) of 128,000 cd/m². These high efficiencies and brightnesses suggest that Mn²⁺-doped PeLEDs could be implemented in lighting or display applications. However, device stability is also important to consider. The team found that introducing TFPPO compromises the stability of Mn²⁺-doped PeLEDs—a decrease from 37.0 to 2.54 min. By analyzing both the optoelectronic and photophysical characteristics of Mn²⁺-doped PeLEDs before and after device operation, the scientists reported insights into this efficiency-stability trade-off.

Researchers at imec and University of Hasselt at Energyville, Belgium, recently set out to improve two key perovskite interfaces for solar cells for efficiency and lifetime.

The work focusses on the upper interface between the perovskite and the fullerene-C60 electron transport layer and the lower interface between the perovskite and the NiOx-based hole transport layer.

Researchers from China's Harbin Institute of Technology and University of Electronic Science and Technology of China have proposed a facile and universal platform to fabricate integrated spectrometers with solution-processable semiconductors by involving the conjugated mode of the bound states in the continuum (conjugated-BIC) photonics.

Acquiring real-time spectral information in point-of-care diagnosis, internet-of-thing, and other lab-on-chip applications requires spectrometers with hetero-integration capability and miniaturized form. Compared to conventional semiconductors integrated by heteroepitaxy, solution-processable semiconductors provide a much-flexible integration platform due to their solution-processability, and, therefore, more suitable for multi-material integrated systems. However, solution-processable semiconductors are usually incompatible with micro-fabrication processes, making them impractical for use in various applications.

Researchers from China's University of Science and Technology (SUSTech), Chinese Academy of Sciences (CAS), City University of Hong Kong (CityU) and Korea University have developed an effective strategy to modify the Tin dioxide (SnO₂)/perovskite buried interface by passivating the buried defects in perovskite and modulating carrier dynamics via incorporating formamidine oxalate (FOA) in SnO₂ nanoparticles.

Tin dioxide (SnO₂) is a commonly used electron transport material for n-i-p-type perovskite solar cells (PSCs) due to its high light transmittance and electron mobility, suitable energy levels, good stability under UV irradiation, and it can be processed at low temperatures. The buried interface of perovskite/SnO₂ plays a major role in achieving high efficiency and stability. However, the non-exposed buried interface is challenging to study and manipulate.

Researchers from China's Hebei University of Technology and Chinese Academy of Sciences have found that increasing the diameter of single-wall carbon nanotubes (SWCNTs) in SWCNT/perovskite QD heterojunctions can improve the optoelectronic performance of the heterojunction between the two materials.

The team systematically tested the performance effects of varying diameters of SWCNTs, a single layer of carbon atoms that form a hexagonal lattice rolled into a seamless cylinder, with different band gaps, or the amount of energy required for an electron to conduct electric current, in heterojunction films with perovskite QDs. Their study indicated that increasing the diameter of SWCNTs improved the responsivity, detectivity and response time of this type of heterojunction film. This effect may be mediated by the enhanced separation and transport of photogenerated excitons, an energy-carrying, neutrally charged electron that combines with a positive electron hole, in the film.

Researchers from Spain's BCMaterials, University of Barcelona and IKERBASQUE have developed water stable perovskites, by adopting a unique additivization strategy to stabilize the FAPI alpha phase. 

Thanks to their thermal stability along with a monocationic and anionic nature, formamidinium lead triiodide (FAPI) perovskites have emerged as an attractive material to avoid thermal degradation and phase segregation and promising photoactive materials for perovskite solar cells. However, the unfavorable phase transition from cubic (3C) to hexagonal (2H) due to the lower formation energy of the latter hinders its immediate use. Stabilizing the 3C phase of FAPI against atmospheric stresses is a critical challenge in PSC research, and the goal of this recent study.