Graphene preparation of new high-efficiency solar cells
The extremely high electron mobility gives the graphene ideal conditions. When the electrons pass through the graphene, they have a mobility of about 100 times. This is compared with silicon. Graphene also has excellent strength, and in fact, it is almost Being transparent (2.3% of light can be absorbed; 97.7% of light can be transmitted), which makes it an ideal candidate for photovoltaic applications, ultra-thin transparent graphene films can replace metal oxide electrodes. Therefore, it may be a promising alternative material to replace indium tin oxide (ITO), which is currently the standard transparent electrode material, and graphene is used as an electrode and can be used in liquid crystal displays. Solar cells, touch screens for iPads and smart phones, and organic light-emitting diode (OLED) displays for televisions and computers.
However, recent studies have shown that doping is necessary in order to utilize the full potential of graphene. The challenge for researchers is to find appropriate manufacturing techniques to produce high-quality graphene sheets with high charge mobilities.
A group of researchers from Germany and Spain recently published a paper, published in "Angewandte Chemie International Edition" entitled "Realization of Adjustable Graphene / Turnip-PPV Hybrid Systems" (Towards Tunable Graphene). /Phthalocyanine-PPV Hybrid Systems), who proposed a chemical method to make non-covalently functional graphene, this material is produced in a large number of low-priced natural graphite.
"So far, functional molecules have been introduced based on photo-active groups, which require interactions with graphene oxides. Therefore, we must tolerate harsh reducing conditions and achieve non-community. Functional functionalized graphene oxide," said Jenny Malig, who was the first author of the paper. "The advantage of our method is the direct stripping of graphene, which uses sonication and accompanying non-covalent functionalization, relying on a photospectroscopic characterization solution."
Malik is a PhD student in the Dirk Guldi group, working with her at the Friedrich-Alexander-Universitat University in Erlangen, Nuremberg. Colleagues and collaborators came from IMDEA-Nanociencia at the Universidad Autónoma de Madrid.
She pointed out that non-covalently exfoliating graphene, the medium used is surfactants (surfactants), which is fully verified. In principle, this concept is derived from carbon nanotube chemistry.
"In addition, pi-surfactants, like amphiphilic perylene or pyrene dyes, have been used to stabilize graphene flakes, which are performed in a suitable solvent," she says. "Inspired by these results, we have turned to more sophisticated molecules such as phthalocyanine oligomers, which have never been used in the dissolution process before."
For this work, there is knowledge that teaches the research that has been completed. The area of ​​chemistry is Carbon Nanotube Chemistry, which was done by Gourtier's team (they wrote the article “Adjusting and Optimizing the Intrinsic Interaction of Phthalocyanine-based PPV Oligomers. And for single-walled carbon nanotubes to achieve n-type/p-type), which is critical, non-covalent functionalized graphene sheets can be prepared, which is a nanocomposite.
However, the study of new electron donor-acceptor hybrids involves graphene, which is more challenging than stripping carbon nanotubes, all under the same conditions. The reason is that, from the perspective of applicable solar cells, the main challenge is nanocomposites in terms of photophysical properties.
"Compared with non-covalent functionalized carbon nanotubes, graphene is considered as a zero-gap semiconductor and does not exhibit significant optical transitions. This is the case in the visible light range, which limits the characterization Techiques," said Marigot.
The team bypassed this issue by selecting a spectator molecule to help identify and characterize the interaction of electrons with receptors.
"Interestingly, we were able to quantify and prove the types of radical cations that formed, this "bystander", which for the first time clearly showed that electron transfer was transferred from the excited dye to the graphene sheet. ,†said Malig. "Finally, the latter forms a convenient tool for testing a wide range of in-situ dyes. It shows that graphene may act as an electron acceptor."
In general, this novel monohybrids material is a new electronic material, especially for printed electronics. Non-covalently functionalized graphenes produce cost-effective new materials that may exhibit new variant properties, unlike non-functionalized graphene. In addition, functional groups can adjust the exfoliation and solubility of graphite/graphene.
"In some devices, the electronic structure of graphene is chemically functionalized. This is an appropriate way. These devices can be designed. All the assemblies use graphene," said Malig.
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