کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1267046 | 1496826 | 2016 | 8 صفحه PDF | دانلود رایگان |
• Highly pure star-like polymers were obtained by using new construction strategy.
• Simple non-emissive core replaced emissive one synthesized by complex procedure.
• The formation of linear polyfluorene can be effectively suppressed in the new system.
• The performance of white device was improved substantially by annealing at 140 °C.
• Tight molecular stacking was responsive for the high efficiency of annealed devices.
A series of novel star-shape like white polymers were synthesized by employing the benzene as the core, and incorporating different amount of bis (4-methoxyphenyl) maleimide guest onto the side-chain of the polyfluorene (PF) arm host. Due to the large feed ratio of core, such a construction strategy could efficiently avoid or suppress the formation of linear PF which always existed in the previous star-like polymers employing guest as core. When applied to the single emitting layer devices fabricated by solution spin-coating method, the efficiency of the devices enhanced gradually with the amount of guest increasing from 0.01% to 2%. The device performance was further improved substantially by annealing at 140 °C. A typical device base on P1 containing 1% dopant exhibited maximal luminous efficiency of 6.13 cd/A. Interestingly, the increase of efficiency is not originated from the self-dopant effect of α or β crystalline phase, which was always produced by thermal treatment at 120 °C in linear or previous star-like polyfluorenes. Morphology analysis disclosed that annealing made the polymeric molecules stack become closer, consequently resulting in a more effectively charge transfer and energy transfer from host to guest. As a result, the compact molecular stacking of the star-shape like polymers should be responsive for the high efficiency of annealed devices. The results would be conducive to design new star-shape like polymers with more arms, and improve the performance of white devices.
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Journal: Organic Electronics - Volume 31, April 2016, Pages 183–190