利用分子链取向技术改进聚合物光电子性能的研究及应用开发

Semiconducting polymers, as novel gain media，have wide potential applications for lasers，optical amplifiers, and optical communication (high speed data communication) due to their high photoluminescence quantum efficiencies (PLQE), wide laser emission wavelength range and large stimulated emission cross-sections. Optically pumped lasers have been demonstrated for a wide range of such materials and for emission wavelength cover whole visible range. However, electrically pumped diode lasers fabricated from organic semiconductors have not yet been realized. One of the reasons is the relatively low charge carrier mobilities of polymer gain media that act against attainment of the high current densities required to reach threshold conditions. Another potenial application of polymer gain media is they can be doped into plastic fibers i.e. poly(methyl methacrylate) (PMMA). The resulting all plastic active fiber would provide optical amplification while signal propagation through it. However, in order to achieve either electrical pumped polyer laser or all plastic active fiber, considerable efforts have to be made to increase net optical gain (and decrease losses) and to improve thermal stability of these gain media. The aim of this project is to improve the optical gain properties, increase intrinsic carrier mobility, and improve thermal stability of polymer gain media via aligning polymer chain to induce optical and electrical isotropic (diachronic) in a polymer or a two polymers blend system. We will first investigate the influence that the polymer chain alignment has on the optoelectronic properties of a polymer in detail. We will then blend two polymers in various ratios and align the polymer chain of the blend. This is to understand the energy transfer behaviour as a function of the blend ratio, degree of chain orientation in a polymer blend system. Consequently, we will study the gain property of aligned polymer gain media in an electrical pumped device system. We will also explore potential application of chain aligned polymer in novel plastic fibers for data communication.

聚合物光增益材料具有高荧光量子效率、宽增益光谱范围和大受激发射截面，在有机激光、光放大、光通讯（高速数据通讯）等领域有着广泛的应用前景。目前，光泵浦聚合物半导体激光器已广为报道，其发射谱已覆盖了整个可见光波段。但是电泵浦激光器尚未实现，原因之一是其相对低的载流子迁移率，使电泵浦条件下产生激光所需要的高电流密度难以达到。聚合物光增益材料的另一个潜在应用是将其掺入塑料光纤，制成活性光导纤维，实现对传输光信号的放大。然而，无论电泵浦激光器还是活性光纤的实现，都要求聚合物的光增益率及其热稳定性的进一步提高。本项目研究目标是利用聚合物分子链取向技术，使材料产生光、电各向异性，提高其定向光增益系数、载流子迁移率及稳定性。并深入研究聚合物单体链取向程度与光电性能变化的对应关系；两种材料共混时，链取向对能量传递的影响。调查链取向的光增益介质在电泵浦器件结构中的性能和探索链取向材料在塑料光纤通讯中的应用。

聚合物发光及光增益材料具有高荧光量子效率、宽增益光谱范围，在有机电致发光器件、激光、光通讯（高速数据通讯）等领域有着广泛的应用前景。目前，光泵浦聚合物半导体激光器已广为报道，其发射谱已覆盖了整个可见光波段。本项目是利用聚合物分子链取向技术，使材料产生各向异性，提高其定向光学性能，如折射率、光吸收及荧光的各项异性，导致聚合物材料沿链取向方向折射率增加；偏振光吸收系数及荧光强度增加。项目研究已经按计划如期完成，并取得以下三个开创性成果：项目深入研究了各种链取向工艺方法，首次成功地将光照取向层技术、打印沉积取向层及活性层技术用于器件工艺；并阐明了各种工艺对聚合物单体链取向程度及其性能变化的影响的机制；首次成功的实现了共混材料的链取向，并深入研究了两种材料共混时，链取向对能量传递的影响。首次在电致发光器件中实现了发光层链取向，并系统研究了链取向的聚合物在电致发光器件结构中的性能。项目还将图形化技术和链取向技术相结合，展示了链取向材料在塑料光纤通讯中的应用。项目研究已发表SCI索引文章24篇，国际会议报告7次，申请发明专利7项，授权4项，转让专利6项。项目研究期间有1名学生获得博士学位，8名学生获得硕士学位。项目研究过程中还与英国帝国理工Jenny Nelson教授（皇家院士）的课题组 、与英国牛津大学数理与生命科学院院长Donal Bradley教授（皇家院士）及西班牙马德里自制大学先进材料与纳米技术国家实验室J. Cabanillas – Gonzalez研究院的课题组建立了长期实质性优势互补的合作, 有多篇合作文章发表在包括Advance Materials, Advance Functional Materials,在内的高影响因子期刊。