Study On Crystallization Behavior And Morphology Of P3HT/PCBM Induced By 1,3,5-TCB

With the depletion of fossil fuels,solar energy as renewable energy have become the focus of attention.Conjugated polymers are important materials for photovoltaic cells.They have strong electron withdrawing group.At present,the conversion efficiency of photovoltaic cells prepared by blending conjugated polymers with electron acceptor materials is still low.However,by regulating the structure of the battery,phase separation of the donor and receptor can be achieved,and separation efficiency of exciton can be improved by the formation of alternation arrangement structure.In this experiment,two kinds of electron donor and acceptor materials,poly(3-hexylthiophene)(P3HT)and[6,6]-phenyl-C61-butyrate methyl ester(PCBM),were selected and their structure were regulated by the method of directional epitaxial crystallization.1.P3HT can be induced to form oriented structure by 1,3,5-trichlorobenzene(1,3,5-TCB),while it has no effect on PCBM.The morphology and structure of the films were characterized by means of polarizing microscope(POM),atomic force microscope(AFM)and transmission electron microscope(TEM).The results show that a large number of oriented lamellae crystals are formed because of lattice matching of P3HT and TCB,and its c axis is parallel to the c axis of TCB crystals.However,the PCBM samples treated under the same conditions have no oriented crystals,and a lot of granular structures have been observed by AFM.2.The phase separation of P3HT/PCBM blends is the best when the mass ratio is 1:1.When the mixing ratio of P3HT and PCBM changes,the morphology and structure of samples are also different.When the mass ratio is 1:1,the alternation arrangement structure is formed,which is the ideal.3.The effect of annealing on P3HT/PCBM blend films was studied.It is found that the morphology and structure of the films annealed at 150 ? for 30 min changed greatly.And the size of the granular structure formed by PCBM increased from 100 nm to 200 nm after annealing.Because surface energy of P3HT and PCBM is different,PCBM will move to the high surface energy interface during annealing,and it will gather on the under surface where the film is in contact with the substrate.