School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
ACS Appl Mater Interfaces. 2012 May;4(5):2551-60. doi: 10.1021/am300231v. Epub 2012 Apr 19.
In the present study, a novel polar-solvent vapor annealing (PSVA) was used to induce a significant structural rearrangement in poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films in order to improve their electrical conductivity and work function. The effects of polar-solvent vapor annealing on PEDOT:PSS were systematically compared with those of a conventional solvent additive method (SAM) and investigated in detail by analyzing the changes in conductivity, morphology, top and bottom surface composition, conformational PEDOT chains, and work function. The results confirmed that PSVA induces significant phase separation between excess PSS and PEDOT chains and a spontaneous formation of a highly enriched PSS layer on the top surface of the PEDOT:PSS polymer blend, which in turn leads to better 3-dimensional connections between the conducting PEDOT chains and higher work function. The resultant PSVA-treated PEDOT:PSS anode films exhibited a significantly enhanced conductivity of up to 1057 S cm(-1) and a tunable high work function of up to 5.35 eV. The PSVA-treated PEDOT:PSS films were employed as transparent anodes in polymer light-emitting diodes (PLEDs) and polymer solar cells (PSCs). The cell performances of organic optoelectronic devices with the PSVA-treated PEDOT:PSS anodes were further improved due to the significant vertical phase separation and the self-organized PSS top surface in PSVA-treated PEDOT:PSS films, which can increase the anode conductivity and work function and allow the direct formation of a functional buffer layer between the active layer and the polymeric electrode. The results of the present study will allow better use and understanding of polymeric-blend materials and will further advance the realization of high-performance indium tin oxide (ITO)-free organic electronics.
在本研究中，采用了一种新颖的极性溶剂蒸汽退火（PSVA）技术，使聚（3,4-乙二氧基噻吩）：聚（苯乙烯磺酸盐）（PEDOT:PSS）薄膜发生显著的结构重排，从而提高其电导率和功函数。通过分析电导率、形貌、顶底表面组成、构象 PEDOT 链和功函数的变化，系统比较了极性溶剂蒸汽退火对 PEDOT:PSS 的影响，并与传统的溶剂添加剂方法（SAM）进行了详细研究。结果证实，PSVA 会引起 PSS 和 PEDOT 链之间的显著相分离，并在 PEDOT:PSS 聚合物共混物的顶表面自发形成富含 PSS 的层，从而改善了导电 PEDOT 链之间的 3D 连接并提高了功函数。所得的 PSVA 处理的 PEDOT:PSS 阳极膜表现出高达 1057 S cm(-1)的显著增强的电导率和高达 5.35 eV 的可调高功函数。将 PSVA 处理的 PEDOT:PSS 薄膜用作聚合物发光二极管（PLEDs）和聚合物太阳能电池（PSCs）的透明阳极。由于 PSVA 处理的 PEDOT:PSS 薄膜中的垂直相分离和自组织的 PSS 顶表面，可以提高阳极的电导率和功函数，并允许在活性层和聚合物电极之间直接形成功能缓冲层，因此具有 PSVA 处理的 PEDOT:PSS 阳极的有机光电设备的器件性能得到进一步改善。本研究的结果将允许更好地利用和理解聚合物共混材料，并进一步推动实现高性能无铟锡氧化物（ITO）的有机电子学。
