Department of Materials Science, Fudan University , Shanghai 200433, China.
ACS Appl Mater Interfaces. 2016 Jul 20;8(28):18301-8. doi: 10.1021/acsami.6b05661. Epub 2016 Jul 6.
Electrofluorochromic (EFC) materials, which exhibit electrochemically controllable fluorescence, hold great promise in optoelectronic devices and biological analysis. Here we design such donor-acceptor (D-A) conjugated polymers-P(TPACO) and P(TCEC)-that contain the same electron-rich and oxidizable polytriphenylamine (PTPA) as π-backbone, yet with different electron-deficient ketone and cyano units as pendant groups, respectively. They both exhibit solvatochromic effects due to intrinsic characteristics of intramolecular charge transfer (ICT). Compared to P(TPACO), P(TCEC) shows stronger ICT, which leads to higher electrochemical oxidation potential and lower ion diffusion coefficient. Moreover, both polymers present simultaneous electrochromic (EC) and EFC behaviors with multistate display and remarkably rapid fluorescence response. The response time of P(TPACO) is as short as 0.19 s, nearly 4-fold faster than that of P(TCEC) (0.92 s). Such rapid response is found to be determined by the ion diffusion coefficient which is associated with the ICT nature. Finally, the EFC display device based on P(TPACO) is successfully demonstrated, which shows green fluorescence ON/OFF switching upon applied potentials. This work has successfully demonstrated that swift EFCs can be achieved by rational modulation of the ICT effect in such D-A conjugated polymers.
电致变色（EFC）材料具有电化学可控荧光性能，在光电设备和生物分析中具有广阔的应用前景。在这里，我们设计了两种供体-受体（D-A）共轭聚合物-P（TPACO）和 P（TCEC），它们都含有相同的富电子和可氧化的聚三苯胺（PTPA）作为π-骨架，但作为侧基的电子缺的酮和氰基单元分别不同。它们都由于分子内电荷转移（ICT）的固有特性而表现出溶剂化变色效应。与 P（TPACO）相比，P（TCEC）表现出更强的 ICT，这导致其电化学氧化电位更高，离子扩散系数更低。此外，两种聚合物都表现出同时的电致变色（EC）和 EFC 行为，具有多态显示和显著的快速荧光响应。P（TPACO）的响应时间仅为 0.19 秒，比 P（TCEC）（0.92 秒）快近 4 倍。这种快速响应被发现取决于与 ICT 性质相关的离子扩散系数。最后，成功展示了基于 P（TPACO）的 EFC 显示器件，其在施加电位时显示出绿色荧光的开/关切换。这项工作成功地证明了可以通过合理调节 D-A 共轭聚合物中的 ICT 效应来实现快速的 EFC。
