Department of Chemistry and Research Institute of Natural Science , Gyeongsang National University , 501 Jinju Daero , Jinju , Gyeongnam 52828 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 Jul 18;10(28):24055-24063. doi: 10.1021/acsami.8b06653. Epub 2018 Jul 3.
Poly(4-vinylphenol) (PVP) is a promising gate dielectric material for organic field-effect transistors (OFETs) and circuits fabricated on plastic substrates. Thermal cross-linking of PVP with a cross-linker, such as poly(melamine- co-formaldehyde) methylated (PMF), at a high temperature (above 170 °C) is widely considered an effective method to remove residual hydroxyl groups that induce polarization effects in the dielectric bulk. However, the threshold voltage shift in transfer characteristics is still observed for an OFET with a PVP-PMF dielectric when it is operated at a slow gate voltage sweep rate. The present study examines the cause of the undesired hysteresis phenomenon and suggests a route to enable a reliable operation. We systematically investigate the effect of the PVP-PMF weight ratio and their annealing temperature on the transfer characteristics of OFETs. We discover that the size of the hysteresis is closely related to the concentration of nonhydrogen-bonded hydroxyl groups in the dielectric bulk and this is controlled by the weight ratio. At a ratio of 0.5:1, a complete elimination of hysteresis was observed irrespective of the annealing temperature. We finally demonstrate a highly reliable operation of small-molecule-based OFETs fabricated on a plastic substrate at a low temperature.
聚(4-乙烯基苯酚)(PVP)是一种很有前途的用于有机场效应晶体管（OFET）和在塑料衬底上制造的电路的栅介质材料。用交联剂如聚(三聚氰胺-甲醛)甲基化（PMF）在高温（高于 170°C）下对 PVP 进行热交联，被广泛认为是去除在介电体内诱导极化效应的残留羟基的有效方法。然而，当以较慢的栅极电压扫描速率操作时，具有 PVP-PMF 介电层的 OFET 仍会观察到阈值电压转移特性的偏移。本研究探讨了产生不理想滞后现象的原因，并提出了一种实现可靠操作的方法。我们系统地研究了 PVP-PMF 重量比及其退火温度对 OFET 转移特性的影响。我们发现，滞后的大小与介电体内非氢键合羟基的浓度密切相关，而这是由重量比控制的。在比例为 0.5:1 时，无论退火温度如何，都观察到滞后完全消除。最后，我们在低温下成功地演示了在塑料衬底上制造的基于小分子的 OFET 的高可靠性操作。
