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Innovation Japan 2023 (August 24 - 25)


Innovation Japan 2023
Perovskite solar cell with low cost and high durability is realized by new device structure and manufacturing process

August 24 - 25th, Innovation Japan 2023 was held in Tokyo Big Site. New topics with focus on perovskite solar cell are closed up.



Fig 1. Manufacturing process flow
As regards perovskite (PVK) solar cell, University of Hyogo reported the latest research result about new device structure and manufacturing process. Its aim is to mass-produce perovskite solar cell with low cost potential and long lifetime at atmosphere environment by all solution-processes inclusive of printing method. In near future, University of Hyogo will establish a venture maker in order to mass-produce this device.

Its original technologies are device structure and manufacturing process. As figure 1, dense TiO2 film is spray-coated on glass substrate with FTO transparent electrode, and then, porous TiO2 is printed by the screen printing method, and then, annealed at 500℃. The next, porous ZrO2 and porous carbon electrode are printed, and then, annealed at 400℃. Finally, Pb series perovskite liquid is injected into above porous layers, and sorbed.


Pic 1. Pilot-produced perovskite solar cell
In short, this device (MPLE：Multiporous-Laered-Electrodes) is advancement type of the conventional Meso-porous type device (transparent electrode/electron transport layer/perovskite layer/hole transport layer/back electrode), and also, not a stack type. Furthermore, in this device, carbon electrode is used as back electrode instead of evaporated Au or Ag. As a result, it can be manufactured at atmosphere by all solution processes. Of course, IPCE (incident photon-to-current efficiency) is relatively high because of Meso-porous type device, which has short movement distance of electron in perovskite layer.

And also, device durability is superior because of high water resistance of carbon electrode. In fact, sufficient durability same as 3000 h was obtained at 85℃, 85%RH environment. This value means maker guarantee is 10 years or over. By the way, ICPE is approximate 12 %.

In the booth, 80×80㎜ sample and small samples were exhibited. This device has been practical use yet. By the way, glass should be used as a substrate because of above process temperature. In short, it's not possible to realize a flexible device using a plastic film.

Durability and efficiency are enhanced by polysilane treatment


Fig 2. Comparison of durability
On the other hand, The University of Shiga Prefecture reported that durability of PVK device was improved by use of polysilan on PVK film.

In this experiment, FTO film, dense TiO2 film, porous TiO2, and CH3NH3PbI2 perovskite film were deposited, and then, DPPS polysilan was spin-coated, and then, annealed at 140 - 220℃. The next, Spiro-OMeTAD film was spin-coated, and then, Au film was evaporated.

Figure 2 shows comparison of IPCE. IPCE of device with treated by chlorobenzene (CB) was relatively low, on the other hand, that of device with CB + DPPS was greatly higher than that of CB device. Furthermore, if the device was annealed at 220℃, IPCE was not almost changed. In short, high durability was obtained.

Water resistance of PVK device is improved by use of PVK solution

Saga University tried to coat PVK film by use of water solution, in order to enhance water resistance of PVK device.

In general, PVK is stable into high density halogenated methylamine. For this reason, water solution inclusive of PVK is used: as a result, water resistance of device was enhanced. In short, it's unnecessary to form gas barrier layer or strong encapsulation film in general.

However, its IPCE was relatively low same as 3%. This value is that of simply sample device (ITO/TiO2/PVK/electrolyte/Au). In short, if device structure is optimized by insert of carrier transport layer and optimization of material and layer, IPCE is expected to be increased to 2 times or over.

Nano mist using plasma has many applications


Fig 3. Structure of plasma Nano mist deposition
Otherwise, Tokyo University of Agriculture and Technology appealed original Nano mist generation technology using plasma for various applications.

As figure 3, various liquids are changed to Nano size mist state by the plasma Nano mist generation system, and then, sprayed on the object. It's possible to change various liquids, such as oil series, water series, to Nano mist state. For example, furtherance of transdermal absorptionanesthetic, increase of combustion efficiency of petrol, sterilization of agricultural crops, and so on. In the field of electric device, it's effective for deposition of Nano size thin film. In this case, it's easy to coat dense and flat thin film.

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