The Mechanism And Applications Of Functionalized Graphene Oxide In Conjugated Polymer Blend Films

Along with the continuous development of human society,the problems of depletion of fossil energy and deteriorating ecological environment are seriously restricting the sustainable development of the world.In addition to optimizing the mining and use of fossil fuels,finding new energy sources that can replace fossil fuels is a new breakthrough,then solar energy has always been the focus of human research and development.Traditional silicon-based solar cells are not conducive to further development and application due to complicated processes and excessive production costs.The rise of organic electronics has gradually brought organic solar cells into the public’s field of vision.The advantages of low cost,light weight,flexibility,and roll-to-roll process production have undoubtedly made organic solar cells a new star in replacing silicon-based solar cells.Based on the optimization of organic materials design,device technology impovements,and effective interface engineering,the energy conversion efficiency of organic solar cells has ushered in a new breakthrough.At present,the efficiency of single-junction organic solar cells has exceeded 15%,and the efficiency of laminated organic solar cells has exceeded 17%.Graphene oxide,as a two-dimensional semiconductor material with excellent performance,has important application value in the field of organic electronics.The band gap-adjustable graphene oxide is used as an electron acceptor,and with a conjugated polymer as an active layer film of an organic photovoltaic device,or as a third element of an active layer film incorporated into an organic photovoltaic device to realize an energy level cascade or a thin film structure.The regulation of graphene oxide is of great significance for reducing the manufacturing cost of polymer photovoltaic devices and improving device performance.However,most of the conjugated polymers can only be dissolved and treated in organic solvents,and thus it is the key that the hydrophilic graphene oxide can be functionally modified to be dispersible in organic solvents,thereby obtaining a uniformly mixed polymer composite film and realizing the high performance of applications.It is of great research value to further explore the molecular packing mode,crystal orientation,charge transfer and transport properties of conjugated polymer molecules on the surface of functionalized graphene oxides to improve the performance of optoelectronic functional devices based on conjugated polymer composite films.The main contents of this research include:1.Functionalized small-sized graphene oxide optimizes crystallinity and phase separation of PTB7:PC7iBM blend films.We modified the graphene oxide with a surfactant,dodecyldimethylammonium bromide(DDAB)ion bond to achieve the preparation of ionic bond functionalized graphene oxide under simpler conditions.The Sono-Fenton reaction reduces the phase size of graphene oxide sheets.The functionalized small-sized graphene oxide(DDAB-sGO)was incorporated into the active layer PTB7:PC7iBM mixture,and the phase separation and the charge transfer characteristics under photoexcitation of the DDAB-sGO-induced photoactive layer films were investigated and prepared,organic solar cells with significantly improved performance were also fabricated successfully.2.Functionalized graphene oxide enables high-efficiency bulk heterojunction organic solar cells with thick active layers.We used PTB7-assisted phase transfer method to prepare functionalized graphene oxide(P-GO)modified by PTB7 π-πstacking,successfully transferred to non-polar solvent chlorobenzene.The crystallinity enhancing mechanism of PTB7 molecules induced by graphene oxide was studied.P-GO was incorporated as a third element into the active layer(PTB7:PC71BM)films of organic photovoltaic devices.The crystal orientation and charge transport properties of P-GO doping to photoactive layer films were investigated.We obtained the the stable-performance organic solar cells with thick active layers,which may promote the roll-to-roll large-scale process production and commercialization of the organic photovoltaic industry.