Polydopamine/Graphene/ZnO Composites Used As Electron Transport Layers For Polymer Solar Cells

Interface modification layer is very important for the construction of polymer solar cells, especially, the photoelectric conversion efficiency and stability of the device can be enhanced by optimizing the interface layer. To the best of our knowledge, transition metal oxides, metal salts and polymers are widely used electron transport layer (ETL) materials. In this paper, the polydopamine(PDA)/graphene/ZnO composites are used as ETL for polymer solar cells.Dopamine is an excellent surface modification material. It can self-oxidation polymerizes to form PDA film, which can be attached to almost all material surfaces. This reaction is very mild and simply operated, and can be applied to fields of energy, environment and biology. At present, in the field of energy, PDA is mainly used in the lithium ion battery and the dye sensitized solar cell, and the application of PDA in polymer solar cells has less research reports. In this article, PDA/graphene/ZnO composites as electron transport layer in polymer solar cells is studied. The preparation and characterization of PDA and the feasibility of applying PDA to the interface of polymer solar cells was firstly studied. Then, the reduction behavior of dopamine on graphene oxide was analyzed. At last, PDA/ZnO and PDA/RGO/ZnO composites are constructed and used as ETL in polymer solar cells. The main research contents are as follows:1. PDA thin films and PDA suspensions were prepared, and their hydrophilicity and optical absorption properties were also characterized. The carbonization behavior of PDA was further discussed, and the carbonization of PDA was analyzed by means of TG, Raman spectroscopy and TEM.2. The reduction behavior of dopamine on graphene oxide was analyzed. By FTIR and XRD characterization, it is found that graphene oxide can indeed be reduced by dopamine. As a mild reducing process, the resulting product is the mixture of PDA, GO and RGO.3. ZnO nanoparticles with hexagonal wurtzite structure approximately 5 nm in diameter has been synthesized. Graphene-based quantum dots (GQDs) were prepared by hydrothermal reduction of PDA-RGO in the etching solution mixture of H2O2 and NH3. At last, PDA/ZnO and PDA/GQDs/ZnO composites were fabricated and used as ETL to PTB7:PC71BM solar cells. The results obtained indicates that the incorporation of PDA/ZnO composites leads to enhanced device performance. However, the application of PDA/GQDs/ZnO composites in PTB7:PC71BM solar cells still needs to be discussed.