†Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea.
§Department of Chemistry, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 790-784, Republic of Korea.
ACS Appl Mater Interfaces. 2015 Jul 15;7(27):15031-41. doi: 10.1021/acsami.5b04248. Epub 2015 Jun 29.
The effect of varying degrees of surface and vertical coverage of gold nanoparticles (Au-NPs) by poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (
PSS), which was used as a capping layer between indium tin oxide (ITO) and a hole transport layer (HTL) on small-molecule fluorescent organic light-emitting diodes (OLEDs), was systemically investigated. With respect to the Au-NP loading amount and size, the resultant current densities influenced the charge balance and, therefore, the OLED device performance. When the capping layer consisted of ITO/Au-NPs/
PSS+Au-NPs, superior device performance was obtained with 10-nm Au-NPs through increased surface coverage in comparison to other Au-NP PEDOT:PSS coverage conditions. Furthermore, the Au-NP size determined the vertical coverage of the capping layer. The current densities of OLEDs containing small Au-NPs (less than 30 nm, small vertical coverage) covered by
PSS decreased because of the suppression of the hole carriers by the Au-NP trapping sites. However, the current densities of the devices with large Au-NPs (over 30 nm, large vertical coverage) increased. The increased electromagnetic fields observed around relatively large Au-NPs under electrical bias were attributed to increased current densities in the OLEDs, as confirmed by the finite-difference time-domain simulation. These results show that the coverage conditions of the Au-NPs by the
PSS clearly influenced the OLED current density and efficiency.
通过聚（苯乙烯磺酸盐）掺杂聚（3,4-亚乙基二氧噻吩）（PEDOT：PSS）对金纳米粒子（Au-NPs）的表面和垂直覆盖率进行不同程度的修饰，该修饰用作铟锡氧化物（ITO）和空穴传输层（HTL）之间的覆盖层，系统地研究了小分子荧光有机发光二极管（OLEDs）。就 Au-NP 的加载量和尺寸而言，所得电流密度影响电荷平衡，从而影响 OLED 器件性能。当覆盖层由 ITO/Au-NPs/PEDOT：PSS+Au-NPs 组成时，与其他 Au-NP PEDOT：PSS 覆盖条件相比，通过增加表面覆盖率，具有 10nm Au-NP 的器件获得了更好的性能。此外，Au-NP 的尺寸决定了覆盖层的垂直覆盖率。由 PEDOT：PSS 覆盖的小 Au-NPs（小于 30nm，小垂直覆盖率）的 OLED 的电流密度降低，这是因为 Au-NP 陷光位抑制了空穴载流子。然而，具有大 Au-NPs（大于 30nm，大垂直覆盖率）的器件的电流密度增加。在电偏压下观察到相对较大的 Au-NP 周围的电磁场增加归因于 OLED 中的电流密度增加，这通过有限差分时域模拟得到证实。这些结果表明，Au-NPs 被 PEDOT：PSS 覆盖的条件明显影响 OLED 的电流密度和效率。
