Technical / research - Page 43

A team of scientists, led by Professor Hairen Tan of Nanjing University, has demonstrated (for was the team states is the first time) bifacial all-perovskite monolithic tandem solar cells and examined their output power potential.

The research team demonstrated the design and fabrication of bifacial all-perovskite tandem solar cells using transparent conductive oxide (TCO) as the back electrode. The bandgap technique of the top subcell was used to obtain current matching under different backlights. The influence of the albedo on the photovoltaic parameters and the spectral sensitivity was systematically investigated. The bifacial tandems reportedly showed a high output power density of 28.51 mW cm⁻² under a realistic rear illumination (30 mW cm^{− 2}). Further energy yield calculation showed substantial energy yield gain for bifacial tandems compared with the monofacial tandems under various ground albedo for different climatic conditions. This work provides a new device architecture for higher output power for all-perovskite tandem solar cells under real-world conditions.

Scientists from the University of Warsaw, Poland-based Military University of Technology, CNR Nanotec, the University of Southampton and the University of Iceland have designed a new photonic system with electrically tuned topological features, constructed of perovskites and liquid crystals. The new system can be used to create efficient light sources.

"We noticed that two-dimensional perovskites are very stable at room temperature, have high exciton binding energy and high quantum efficiency", said PhD student Karolina Lempicka-Mirek from the Faculty of Physics at the University of Warsaw, the first author of the publication. The team explained that these special properties can be used in the construction of efficient and unconventional light sources. 

Researchers from Zhejiang Energy Group R&D and the Chinese Academy of Sciences (CAS) have reported what they say is "the first monolithic perovskite/silicon tandem featuring an industrially applicable front-side-nanostructured black silicon with a tunnel oxide passivated contact (TOPCon)".

The TOPCon together with the surface reconstruction of black silicon contributes to the high-level surface passivation without sacrificing the broadband light trapping. Additionally, the reconstructed nanotexture significantly facilitates the wetting of perovskite and acts as a nanoconfining scaffold to guide the vertical growth of perovskite.

Researchers from Japan-based National Institute for Materials Science (NIMS) recently developed a durable 1cm² perovskite solar cell capable of generating electricity for more than 1,000 continuous hours at a photoelectric conversion efficiency (i.e., power generation efficiency) of more than 20% in exposure to sunlight.

As this solar cell can be fabricated on the surface of a plastic material at approximately 100°C, this technique could have great potential for developing light, versatile solar cells.

Researchers from Israel's Bar-Ilan University and Weizmann Inst. of Science have measured the effect of humidity on hardness and elastic modulus (E) for two series of lead halide perovskite single crystals. The results indicated the influence of hydrogen (H)-bonding, bond length, and polarization of the ions in lead halide perovskite single crystals.

The team detected an inverse relation between hardness and modulus, which was strengthened with increased humidity. Their findings shed light on the material's distinct structure and properties at the atomic scale. The conclusion of this work was based on the evaluation of outcomes of various nano-indentation techniques that differentiated between surface and bulk E and explored different manifestations of hardness.

University of Freiburg researchers have evaluated how suitable halide-perovskites are for advanced photoelectrochemical battery applications. The recent paper unveiled important findings that could influence the use of organic-inorganic perovskites as multifunctional materials in integrated photoelectrochemical energy harvesting and storage devices.

Importantly, the research has revealed the tendency for 2-(1-cyclohexenyl)ethyl ammonium lead iodide (CHPI) perovskites to dissolve in highly polar electrolytes commonly employed in current lithium-ion batteries. The selection of low polarity electrolytes stabilizes the CHPI electrode material, leading to purely capacitive behaviors in batteries and minimizing lithium-ion intercalation. However, when applying a galvanostatic charge whilst the perovskite electrode material is in contact with electrolyte leads to photo corrosion and CHPI phase dissolution.

Researchers from Helmholtz-Zentrum Berlin (HZB) have demonstrated the scalable fabrication of perovskite/silicon tandem solar cells with optimized bandgap using the slot-die coating method. The team used slot-die coating for an efficient, 1.68 eV wide bandgap triple-halide (3halide) perovskite absorber, (Cs_0.22FA_0.78)Pb(I_0.85Br_0.15)₃ + 5 mol % MAPbCl₃. The team demonstrated that the fabrication route is suitable for tandem solar cells without phase segregation. 

The researchers successfully fabricated a triple-halide perovskite film with top cell optimized bandgaps, high PL quantum yield (PLQY), and improved film quality using the slot-die coating method. They have also efficiently integrated halide perovskites with industrial silicon bottom cells in a tandem architecture, demonstrating the potential of fabricating industrially relevant and scalable perovskite solar cells.

Researchers from Russia's Kazan Federal University have reported on a new method for the fabrication of polypropylene/metal halide perovskites composite in one single step by co-extrusion of the perovskite precursors with polypropylene. Perovskite quantum dots are formed in-situ, and are uniformly distributed in the polymer matrix.

The team said that the material demonstrated high quantum yield and unprecedented stability at ambient conditions. The team further demonstrated that an extruded strand can be used directly as a filament for 3D printing technology. The developed method is simple, has literally no waste, and is unlimitedly scalable. It offers a way to efficiently solve the problem of stability of perovskites, simultaneously involving them into additive manufacturing technologies.

Researchers from Peking University, China Automotive Technology and Research Center, Beijing Institute of Technology and Jiangnan University recently demonstrated the ability of tuning the Fermi level of the hole transport layer (HTL) to reduce the energy level difference (Schottky barrier) between HTLs and Cu. In addition, the team identified that the balance of energy level difference between HTL and adjacent layers (including perovskite and Cu) is crucial to efficient carrier transportation and photovoltaic performance improvement in the PSCs.

The team's effort was aimed at addressing the challenge of developing low-cost and stable metal electrodes, which could be very important for mass production of perovskite solar cells (PSCs). As an earth-abundant element, Cu becomes an alternative candidate to replace noble metal electrodes such as Au and Ag, due to its comparable physiochemical properties with simultaneously good stability and low cost. However, the undesirable band alignment associated with the device architecture impedes the exploration of efficient Cu-based n-i-p PSCs.

A research team, led by Dr. Lei Su at Queen Mary University of London in collaboration with University College London, recently designed a new application of perovskites as optical fibers.

Optical fibers are thin wires in which light travels at a superfast speed—100 times faster than electrons in cables. These tiny optical fibers transmit the majority of our internet data. At present, most optical fibers are made of glass. The perovskite optical fiber made by Dr. Su's team consists of just one piece of a perovskite crystal. The optical fibers have a core width as low as 50 μm (the size of a human hair) and are very flexible—they can be bent to a radius of 3.5 mm.