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Innovation Japan 2024 (August 22 - 23)


Innovation Japan 2024
2D perovskite is vertically orientated instead of 3D perovskite

August 22 - 23th, Innovation Japan 2024 was held in Tokyo Big Site. New topics of electric device are closed up.

As concerns perovskite solar cell, Sophia University proposed new perovskite compounds based on new concept.


Fig 2. Comparison of layer structure


Fig 1. Estimate result of durability
As you know, in the conventional perovskite compound, all tops of halogen metal octahedron are catenated with neighbor octahedron. However, perovskite material is easy to deteriorate by H2O because of its 3D structure. Therefore, the research group invented 2D structure, which was catenated only x, y, z orientations. Figure 1 shows durability estimate result at 25℃ and 40 - 50%RH. As a result, durability of 2D structure is clearly superior than that of 3D structure.

However, in 2D structure, vertical carrier movement is decreased because of hydrophobic group. For this reason, it's necessary to vertically orientate 2D compound. As its methods, molecule structure, balance control of hydrophobic and hydrophilic groups, coating method, kind of solvent and others are necessary to devise.

For the present moment, IPCE (Incident photon-to-current efficiency) of 2D type Pb series perovskite device is approximate 10 %. In near future, the research group will develop Sn series perovskite device with high IPCE, is competed with Pb series device.

Amorphous ITO film is crystallized by irradiation of DUV laser


Fig 3. Manufacturing process image and process temperature
With respect to manufacturing process, Kyushu University announced to adopt laser irradiation method, in order to upgrade ceramics film on plastic substrate, which had poor heat resistance. In this process, KrF DUV laser (wavelength 248 nm) was used because of shallow penetration length, due to minimum thermal damage against plastic substrate. As figure 3, thermal damage can be minimized because of local and rapid annealing on surface only.

For example, amorphous ITO can be crystallized completely and easily by this method. And also, if deposited Cu film is irradiated by DUV laser, film resistance is decreased because of increase of Cu grain size. Furthermore, if two or three metals (solid) are put on plastic substrate, they are changed to alloy films by this method.

Self-repairing and chemical recycle are realized by use of originally optical resin


Pic 1. Polydithiourethane sheet
As regards material, Kyushu Institute of Technology appealed a revolutionarily optical resin. It can be not only self-repaired, but also, chemical recycled. In short, in case of scratch, it's self-repaired, on the other hand, in case of breaking,it can be chemically reuse.

The research group has succeeded to develop polydithiourethane (PDTU). As figure 4, at room temperature, it's self-repaired by polyaddition. On the other hand, it can be recycled because of depolymerization by anneal at 150 ℃. In short, self-repairing at light damage, chemical recycle at deep damage are realized.

Picture 1 shows PDTU sheets. Its transmittance is 75 % and over. For this reason, it can be used as optical film and sheet, lens, and so on.


Fig 4. Mechanism of self-repairing and chemical recycle



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