| 초록 |
Molecular weight of conjugated polymers significantly change crystallinity, solubility of organic solvents and miscibility with other polymers, which is essential aspects for determining performance and stability of all-polymer solar cells. Here in, a series of n-type naphthalene diimide (NDI) bithiophene copolymers (P(NDI2HD-T2), HD= 2-hexyldecyl) with different molecular weights (Mn = 14 , 23, 50 kg/mol) were synthesized. Their electrical, structural and photovoltaic properties were investigated. Particularly, pristine films of P(NDI2HD-T2) displayed clear tendencies of packing structures followed by grazing incidence X-ray scattering data. High Mn P(NDI2HD-T2) film preferred face-on oriented packing, while low Mn P(NDI2HD-T2) film favored edge-on directed packing. Finally, improved charge transport mobility of optimized device of high Mn P(NDI2HD-T2) with donor PTB7-Th lead to high power conversion efficiency 5.85% compared to 4.29% of low Mn P(NDI2HD-T2) without additive. |
