Yang Jinxin, He Pei, Derby Brian
Department of Materials, University of Manchester, Oxford Rd., ManchesterM13 9PL, U.K.
School of Physics and Electronics, Hunan Key Laboratory of Nanophotonics and Devices, Central South University, Changsha, Hunan410083, P. R. China.
ACS Appl Mater Interfaces. 2022 Aug 31;14(34):39601-39609. doi: 10.1021/acsami.2c11133. Epub 2022 Aug 18.
Continuous conducting lines of width 5-20 μm have been printed with a Ag nanoparticle ink using drop-on-demand (DOD) electrohydrodynamic (EHD) inkjet printing on Si and PDMS substrates, with advancing contact angles of 11° and 35°, respectively, and a zero receding contact angle. It is only possible to achieve stable parallel sided lines within a limited range of drop spacings, and this limiting range for stable line printing decreases as the contact angle of the ink on the substrate increases. The upper bound drop spacing for stable line formation is determined by a minimum drop overlap required to prevent contact line retraction, and the lower bound is governed by competing flows for drop spreading onto an unwetted substrate and a return flow driven by a Laplace pressure difference between the newly deposited drops and the fluid some distance from the growing tip. The upper and lower bounds are shown to be consistent with those predicted using existing models for the stability of inkjet printed lines produced using piezoelectric droplet generators. A comparison with literature data for EHD printed lines finds that these limiting bounds apply with printed line widths as small as 200 nm using subfemtoliter drop volumes. When a fine grid pattern is printed, local differences in Laplace pressure lead to the line width retracting to the minimum stable width and excess ink being transported to the nodes of the grid. After printing and sintering, the printed tracks have a conductivity of about 15%-20% of bulk Ag on the Si substrate, which correlates with a porosity of about 60%.
已使用按需滴注（DOD）电液动力（EHD）喷墨打印技术，将宽度为5 - 20μm的连续导线，用银纳米颗粒墨水打印在硅和聚二甲基硅氧烷（PDMS）基板上，前进接触角分别为11°和35°，后退接触角为零。只有在有限的墨滴间距范围内才能实现稳定的平行边导线，并且随着墨水在基板上接触角的增加，稳定线条打印的这个限制范围会减小。稳定线条形成的上限墨滴间距由防止接触线回缩所需的最小墨滴重叠决定，下限则由墨滴在未湿润基板上扩散的竞争流以及由新沉积墨滴与距生长尖端一定距离处的流体之间的拉普拉斯压差驱动的回流控制。结果表明，上下限与使用现有模型预测的使用压电液滴发生器产生的喷墨打印线条的稳定性一致。与关于EHD打印线条的文献数据比较发现，这些限制界限适用于使用亚飞升墨滴体积、宽度小至200nm的打印线条。当打印精细网格图案时，拉普拉斯压力的局部差异会导致线条宽度回缩到最小稳定宽度，多余的墨水被输送到网格节点。打印并烧结后，在硅基板上打印的线路的电导率约为块状银的15% - 20%，这与约60%的孔隙率相关。
