Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
ACS Appl Mater Interfaces. 2014 Jan 8;6(1):83-93. doi: 10.1021/am4025406. Epub 2013 Sep 25.
Poly(silafluorene)s (PSFs) are promising light-emitting materials with brilliant solid-state blue luminescence, high quantum efficiency, excellent solubility, and improved thermal and chemical stability. PSFs are reported to have high electron affinity and conductivity originating from σ*-π* conjugation between the σ*-antibonding orbital of the exocyclic Si-C bond and the π* antibonding orbital of the butadiene fragment, a promising characteristic for improved charge carrier balance in OLEDs. In this paper, we present a protocol for photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 10 μm. The procedure begins by converting polymers (Mn = 50-55 kg/mol, PDI = 1.8) with cyclohexenyl and norbornenyl containing side chains to their respective epoxides using the Prilezhaev reaction and m-chloroperoxybenzoic acid (m-CPBA). Using the I-line (365 nm) of a Karl Suss MA6 mask aligner, a 1 s UV light exposure of the photoacid generator (PAG) bis(4-tert-butylphenyl)iodonium hexafluoro-phosphate (DtBPI-PF6) generates sufficient protons to catalyze epoxide ring-opening and form a bridging network of covalent C-O bonds which renders the material insoluble in developing solvents such as toluene or THF. The resultant cross-linked material possess characteristic blue photoluminescence with solid state quantum yields >80%. Polymer films have excellent transparency (with a measured Eg ≈ 3.0 eV). Energy levels determined using cyclic voltammetry were -5.7 and -2.7 eV for HOMO and LUMO, respectively. Additionally, several device applications are demonstrated which incorporate cross-linked films. These include examples of solid state lasing in the region of 420-450 nm from cross-linked films on second order corrugated silica substrates (Λ = 200 nm). OLEDs were also prepared with a cross-linked emitting layer as part of a trilayer device which we report to have a maximum external quantum efficiency of 3.2% at 33 mA/cm(2) and a stable blue-violet emission with an electroluminescence maximum at 410 nm. Photopatternable PSF epoxides are also shown to be efficient hosts for Förster energy transfer and we provide examples of pattern layers incorporating small molecule emitters which emit in both the red and green while blue emission of the host is effectively suppressed.
聚（硅芴）（PSFs）是一类很有前途的发光材料，具有出色的固态蓝色发光、高光量子效率、良好的溶解性以及改进的热稳定性和化学稳定性。PSFs 的报道具有高电子亲和能和电导率，源于外环 Si-C 键的 σ*-反键轨道和丁二烯片段的 π反键轨道之间的 σ-π*共轭，这是改善 OLED 中电荷载流子平衡的一个有前途的特性。在本文中，我们提出了一种用分辨率超过 10μm 的方法对聚（3,6-二甲氧基-9,9-二烷基芴）衍生物进行光图案化的方案。该程序首先使用 Prilezhaev 反应和间氯过氧苯甲酸（m-CPBA）将含有环己烯基和降冰片烯基侧链的聚合物（Mn=50-55kg/mol，PDI=1.8）转化为相应的环氧化物。使用 Karl Suss MA6 掩模对准器的 I 线（365nm），对光酸产生剂（PAG）双（4-叔丁基苯基）碘鎓六氟磷酸盐（DtBPI-PF6）进行 1s 的 UV 光曝光，产生足够的质子来催化环氧化物开环，并形成共价 C-O 键的桥接网络，使材料在开发溶剂（如甲苯或 THF）中不溶。所得交联材料具有特征性的蓝色光致发光，固态量子产率>80%。聚合物薄膜具有极好的透明度（测量的 Eg≈3.0eV）。使用循环伏安法确定的能级分别为 HOMO 和 LUMO 的-5.7 和-2.7eV。此外，还展示了几种包含交联膜的器件应用。这些应用包括二阶波纹状二氧化硅衬底上交联膜的 420-450nm 区域的固态激光的实例（Λ=200nm）。还制备了具有交联发射层的 OLED，作为三层器件的一部分，我们报告在 33mA/cm2 时最大外部量子效率为 3.2%，在 410nm 处具有稳定的蓝紫光发射。光可图案化的 PSF 环氧化物也被证明是Förster 能量转移的有效主体，我们提供了包含小分子发射器的图案层的实例，这些发射器同时在红色和绿色中发射，而主体的蓝色发射则被有效抑制。
