Solution-Processed, Air-stable, and High-Cutoff Frequency Organic Transistors for Wireless Communication Systems

尽管对有机场效应晶体管(OFET)的研究已有20多年的历史，但有关空气稳定的OFET开关频率超过1 MHz的报道很少。另一方面，对廉价的模拟和灵活的电路应用的需求很大，例如工作在数十MHz甚至接近GHz频率的高频放大器或低电压低噪声接收器电路。为了实现晶体管工作的应用，例如，在工业、科学和医学(ISM)无线电频段(13.56 MHz或27.12 MHz)内以公共无线频率工作的放大器电路中，需要显著提高单个OFET的传输频率，并将其推入50-200 MHz的范围。渡越频率主要受晶体管几何尺寸和半导体材料的本征载流子迁移率的限制。到目前为止，大多数最近报道的改进都集中在晶体管的几何形状上，并且已经展示了几个有前途的概念，特别是具有垂直沟道的布局。然而，将这些现有的器件概念与超高迁移率有机半导体材料相结合的潜力尚未得到充分开发。这项工作的主要目标是开发一种坚固的制造方案，使柔性基板上的OFET能够以50 MHz以上的开关速度工作。我们最近已经能够通过与柔性基板兼容的溶液沉积方法来形成超高性能的场效应管。通过对工艺条件的仔细控制，我们已经从商业上可获得的半导体针尖--并五苯的高度结晶的印刷薄膜中获得了高达11 cm^2/vs的载流子迁移率，而对于同样商业上可获得的C8-BTBT与聚合物聚苯乙烯的旋涂混合油墨，其载流子迁移率高达43 cm^2/vs。建议的目标将通过将这些在获得非常高的电性能薄膜方面的技术突破与现有的制造具有短沟道长度的OFET的方法相结合来实现。我们方法的一大优势是它与灵活的塑料无线技术愿景背后的关键思想之一兼容：低成本！这个项目的结果将是一个解决方案-沉积(打印！)一种方法，可以在塑料衬底和空气稳定的商用半导体材料上廉价地制造渡越频率超过50 MHz的OFET。

Even though organic field effect transistors (OFETs) have now been researched for more than 20 years there are only very few reports of air-stable OFETs switching at frequencies exceeding 1MHz. On the other hand, there is a great demand for inexpensive analog, and flexible circuit applications such as high-frequency amplifiers or low-voltage low-noise receiver circuits working at tens of MHz or even close to GHz frequencies. In order to enable applications in which transistors work, for example, in amplifier circuits operating at common wireless frequencies within the Industrial, Scientific and Medical (ISM) radio bands (13.56MHz or 27.12MHz), the transit frequency of the individual OFET needs to be significantly improved and pushed into the range of 50-200MHz. The transit frequency is mainly limited by the transistor geometry/dimensions and the semiconductor material's intrinsic charge carrier mobility. So far, most of the recent reported improvements have focused on the transistor geometry and several promising concepts, especially layouts with vertical channels have been demonstrated. However, the potential to combine these existing device concepts with ultra-high mobility organic semiconductor materials has not been fully exploited yet. The main objective of this work is to develop a robust fabrication scheme that enables OFET on flexible substrates to work at switching speeds above 50MHz. We have recently been able to form ultra-high performance OFETs from solution-deposition methods that are compatible with flexible substrates. By careful control of the processing conditions we have obtained charge carrier mobilities as high as 11cm^2/Vs from printed highly crystalline films of the commercially available semiconductor TIPS-pentacene, and mobilities as high as 43cm^2/Vs for spin coated blended inks of the also commercially available C8-BTBT with the polymer polystyrene. The proposal objective will be achieved by combining these technological breakthroughs in obtaining very high electrical performance thin films with existing approaches to fabricate OFETs with short channel lengths. One great advantage of our approach is that it is compatible with one of the key ideas behind the vision of flexible, plastic wireless technologies: low cost! The result of this project will be a solution-deposition (printing!) method by which OFETs with transit frequencies above 50 MHz can be inexpensively fabricated on plastic substrates and from air-stable and commercially available semiconductor materials.