After a delay in the Tiger Shark programme, South Korean submarines will soon be armed with a new type of heavyweight torpedo manufactured in-country — and manufacturer LIG Nex1 may also target the export market. The supply of the missiles could help Ukraine alleviate pressure on its Black Sea coast, which has effectively been under blockade by the Russian Navy since the beginning of the invasion. Flurries of criticism about Australia's future frigates have been growing in intensity, but BAE Systems has come out of its corner to counter the narrative.
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The Soviet flag is used when the equipment in question was produced prior to This list is constantly updated as additional footage becomes available. Our list showing destroyed and captured Ukrainian vehicles and equipment can be found here. Click on the numbers to get a picture of each individual captured or destroyed vehicle.
Recommended Articles:. By Oryx - Thursday, February 24, Newer Post Older Post Home. Check Out Our Book! In contrast, OSCs have low dielectric constants, giving large Eb values in the range of 0. In most OPVs, the donor will absorb the most light, and therefore the exciton will be generated on this material. At the interface with the acceptor, the exciton will dissociate. The steps that govern OPV function can be summarised as:. If the energy of light being absorbed is greater than the band gap, the electron will move to a higher energy level than the LUMO and decay down.
Thermalisation is a key energy-loss mechanism in photovoltaics. Diffusion of the exciton to a donor-acceptor interface. Once formed, the exciton diffuses through the OSC component to the donor-acceptor interface, where the offset between LUMO levels will drive exciton dissociation. This must occur within a certain amount of time. At the interface, the electron will move to the acceptor material and the hole will remain on the donor. These charge carriers will still be attracted, and so form a charge-transfer state.
When the distance between the pair increases, the attraction decreases. Eventually, the binding energy between them is overcome by thermal energy, and a charge-separated state is formed. While the electron-hole pair are still attracted in the charge-transfer state, recombination can occur across the interface between the two materials. The charge-carriers will then diffuse to the appropriate electrodes i. At the electrodes, the charge carriers are collected and used to do work in the external circuit of the cell — producing a current.
At several stages, the electron and hole can recombine — at which point the absorbed energy used for initial excitation is wasted. Both of these processes can be radiative where a photon is released or non-radiative where a photon is not released. The first two-component OPV was proposed by Tang in , 8 but efficiencies remained very low for several years due to the reliance on bilayer cells.
Excitons can only dissociate at the interface between donor and acceptor, and can generally only diffuse approximately 10nm before decaying back to the ground state. The solution to this was proposed in , and is known as the bulk heterojunction BHJ cell.
The majority of OPVs used in modern research are solution-processed BHJ cells, where the architecture can be classified as conventional or inverted, depending on the orientation of the electrodes pictured in Figure 5. There remains a small amount of work using planar bilayer junctions 18 in research but these will not be discussed here.
Charge-carrier transport is facilitated by hole-and electron-transporting interfacial layers on either side of the active layer. These layers promote the transport of one type of charge carrier through favourable energy level positioning, whilst discouraging the transport of the other carrier.
As such, the HTL is sometimes known as the electron-blocking layer, and vice versa. For many years, the majority of acceptors used were derived from fullerene normally in the form of PCBM. However, there has recently been a significant movement towards non-fullerene acceptors NFAs , especially those based on small molecules.
These have yielded higher efficiencies 1 and stabilities 19 than fullerene-based acceptors covered in more detail in this overview , and in previously published posts. As opposed to typical fullerene acceptors, which have poor absorption of light in the visible regime, NFAs are typically designed to absorb highly, allowing exciton generation in both the donor and acceptor components of the active layer.
Donor OSCs vary more widely but are often polymer-based. OPV JV behaviour is typically modelled using the equivalent circuit model, which literature has discussed in great detail. Other popular characterisation methods include external quantum efficiency EQE , stability measurements, and assessment of the absorption and photoluminescence of the active layer. Whilst the efficiencies of OPVs have steadily increased since their introduction, fundamental limits on their efficiency still remain.
Here, efficiency is unavoidably lost due to insufficient energy of light entering the device. The energy of absorbed light being higher than the band gap results in energy loss due to thermalisation of the electron, entropic losses, and radiative recombination. The main limitations here have been cited as BHJ morphology, narrow absorption, reduced charge carrier transport and mobility, and high recombination leading to voltage losses.
Whilst some radiative recombination is intrinsic to the cell, non-radiative recombination can be avoided, and reduction of this is key to improving efficiencies. Whilst a large majority of OPV literature remains focused on efficiency values, the main issues restricting OPV commercialisation are scalability and long-term stability. Indeed, some literature has suggested that the current efficiencies obtained could be competitive with other technologies if scaled appropriately.
OPVs have struggled with long-term stability, mostly due to damage from water and oxygen ingress.
OPVS. %. May 24, a.m. EDT. Real Time Quote. Open. $ Previous Close YTD Change. 9,%. 12 Month Change. %. Austal unveiled a new range of offshore patrol vessels at Indo Pacific Based on the in-service Evolved Cape Class Patrol Boat, the ". This report provides an in-depth look at the acquisition priorities for the world's navies and insights into global investment trends. Please note: That all.