GOALI: Nanoparticle-Enabled Printing of Large-Area Electronic Hierarchical Systems

该项目的研究目标是为无机半导体纳米颗粒油墨创造新的低温、基于纳米颗粒的打印工艺，以便能够制造用于无线应用的低成本、全打印设备，例如WiFi和蜂窝通信。尽管无机半导体纳米颗粒的烧结温度可能低于其块状半导体纳米颗粒，但这些温度通常显著高于150℃，这是低成本聚酯或纸基材所允许的最高加工温度。将探索新的低温烧结工艺，以提高印刷纳米颗粒薄膜的半导化性能，而不增加高于该目标温度的加工过程中的最高温度。建议的方法包括使用非专有基准打印平台从模型半导体纳米颗粒墨水制备纳米级薄膜。起始粉末和所得薄膜的纳米结构特征将与器件性能和薄膜迁移率定量相关。采用两种新的工艺方法：氧化物半导体的沉淀烧结和核壳结构的元素纳米粉的金属纳米膜介导的烧结，探索增加颗粒-颗粒接触面积所需的工艺条件。该项目将专注于低毒的无机半导体纳米墨水系统，其元素成分尚未被欧盟禁止在电子产品中使用。(最近的欧盟立法(WEEE和RoHS)禁止在电气和电子设备中使用Cd、Pb和Hg。)通过将理论、现场和非现场电子显微镜实验与纳米颗粒印刷薄膜的半导体性能测量相结合，拟议的研究将寻求对纳米颗粒结构和由此产生的纳米颗粒印刷薄膜的结构如何限制薄膜中的半导体性能的基本理解，与在大块单晶中观察到的结构相比。这一研究项目将有助于理解纳米颗粒烧结的尺寸和形状相关性，了解所提出的创新加工技术的界面过程，并为当前和下一代印刷电子产品的纳米颗粒、纳米颗粒油墨和印刷工艺的设计建立基于材料科学的指导方针。这项研究的影响预计将是重大的，使印刷技术能够在广泛的应用中使用，包括但不限于发射柔性显示器、全印刷移动设备(例如纸质手机)和高性能传感器的普遍使用。这远远超过了目前通过非烧结无机墨水系统或有机印刷电子设备所能实现的。这种低温烧结工艺可能也适用于制造广泛的非电应用的无机纳米颗粒涂层和薄膜。

The research objective of this GOALI project is to create new low temperature, nanoparticle-based printing processes for inorganic semiconductor nanoparticle inks in order to enable fabrication of low cost, all-printed devices for wireless applications, such as WiFi and cellular communications. Although inorganic semiconductor nanoparticles may sinter at lower temperatures than their bulk counterparts, these temperatures are generally significantly higher than 150C, the maximum processing temperature allowable with low cost polyester or paper substrates. New low temperature sintering processes will be explored to improve the semiconducting performance of the printed nanoparticle films without increasing the maximum temperature during processing above this target temperature. The proposed approach includes preparation of nanoscale films from model semiconductor nanoparticle inks using non-proprietary benchmark printing platforms. The nanostructural characteristics of the starting powders and resulting films will be related quantitatively to device performance and film mobility. The processing conditions necessary to increase particle-particle contact area will be explored using two new processing methods: precipitation sintering for oxide semiconductors and metal nanofilm mediated sintering for core-shell structured elemental nanopowders. This project will focus on inorganic semiconductor nanoparticle ink systems with low toxicity, whose elemental constituents have not been banned in electronics by the European Union. (Recent EU legislation (WEEE and RoHS) bans the use of Cd, Pb, and Hg in electrical and electronic devices.)By combining theory and in-situ and ex-situ electron microscopy experiments with measurements of the semiconducting performance of nanoparticle printed films, the proposed research will seek a fundamental understanding of how nanoparticle structure and the resulting structure of the nanoparticle-based printed films limit the semiconducting properties in the films as compared that observed in bulk single crystals. This research project will contribute to the understanding of size- and shape-dependence of nanoparticle sintering, to the understanding of interface processes for the proposed innovative processing techniques, and to the establishment of materials science-based guidelines for the design of nanoparticles, nanoparticle inks, and printing processes for current and next generation printed electronics.The impact of this research is expected to be significant, allowing the use of printing technologies in a wide range of applications, including but not limited to, emissive flexible displays, all-printed mobile devices (e.g., a paper cellphone) and pervasive use of high performance sensors. This is far beyond what is currently achievable through non-sintered inorganic ink systems or organic printed electronics. Such low temperature sintering processes might be adaptable, as well, to the fabrication of inorganic nanoparticle coatings and thin films for a wide range of non-electrical applications.