The morphology of active layer for organic solar cells is critical to optimize the fill factor of the devices. To investigate the relationship between performance and active layer morphology of organic solar cells (OSCs) , 1,8-diiodooctane (DIO) additive, and 2,2′-[[6,6,12,12-Tetrakis(4-hexylphenyl)-6,12-dihydrodithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene-2,8-diyl]bis[methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]]bis[propanedinitrile] (ITIC) small molecular electron acceptor were used to regulate the aggregation morphology of copolymer Poly[[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]-2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]] polymer (PBDB-T) electron donor from solution state to solid state. Many measurements were used to research the morphology, optical and electrical characteristics of active layers and OSCs to explore the relationship among the morphology, photophysical property, and performance of PBDB-T-based devices. Such as atom force microscopy (AFM), steady-state absorption (UV-Vis), time-resolved absorption (TA), spectroelectrochemistry (SEC) and current-voltage (J-V). The results show that DIO can refine the aggregation scale of PBDB-T during the dissolution process, whereas both the aggregation scale and aggregation behaviors of PBDB-T donor are affected by ITIC acceptor molecules. Furthermore, the bulk heterojunction structure (BHJ) morphology of active layer can be optimized during the DIO evaporation process. TA kinetic data indicates that the population and lifetime of charged species are improved in the DIO-treated BHJ active layer.

Optimize separation structure of donor-acceptor phase to adjust the fill factor in PBDB-T-based organic solar cells

2019 Spring National Meeting

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