Study On Phase Separation Structures Of Organic Polymer Blend Systems

As a novel green energy technology,organic solar cell has been developing rapidly in recent years,especially accompanied with the breakthrough of the power convert efficiency?>15%?in the single junction devices.Here,controllable morphology is a key issue for organic solar cells,which has been attracted extensive attention for researchers.This paper focuses on the aggregated structure of organic conjugated polymers,and discusses the influence of different external conditions on the phase separation structure in organic polymer blends.The main research content is as follows:1.Through UV-vis,GIWAXS and AFM characterization,the aggregation structure of P3HT,PTB7,PBDB-T and ITIC are investigated under different external conditions.It is found that annealing is beneficial for the formation of aggregation of P3HT chains.When annealing temperature is higher than glass transition temperature?T_g?,the reorganization of crystalline orientation occurs,which changes from the original face-on orientation to the edge-on one.The aggregation of PTB7 in solution is not sensitive to concentration.The aggregation behavior of PTB7 in solution was similar to that in film,but the degree of aggregation is inceased in film.PBDB-T also shows strong aggregation in CB solution,and could be deaggregation in the temperature of over 90?.ITIC annealed film shows stronger crystallinity and more orderly arrangement than the pristine one.The crystallization by annealing is irreversible when we repeatedly heat and cool the thin film.2.The aggregation structures of fullerene system P3HT:PC₆₀BM,non-fullerene system PBDB-T:ITIC and PTB7:ITIC were discussed under different external conditions.P3HT component makes contributions to the aggregation behaviours in P3HT:PC₆₀BM blend film.After annealing,the P3HT:PC₆₀BM blend film shows orderly arrangement as the the formation of P3HT aggregate,which is originated from the tighter?-?stacking between the chain segments.The aggregation of PBDB-T:ITIC and PTB7:ITIC solutions are not sensitive to their concentrations.The molar concentration at 10^-3 M is sufficiently concentrated for the PBDB-T:ITIC system,but the opposite for the PTB7:ITIC system.However,the degree of aggregation becomes higher in both blend symstems.In the PBDB-T:ITIC or PTB7:ITIC blend film,the crystallite phase along the out-of-plane direction could be controlled by thermal annealing treatment,the content of ITIC and the addition of DIO additives.Thermal annealing treatment could enhance the face-on orientation for the bulk or blend film.The content of ITIC seems to be a complicated variation as the interference of multiple intermolecular interactions.The introduction of DIO additive is not conducive to the growth of pure crystallites,but post annealing treatment could improve the structural mophorlogy.