Minority and Majority Charge Carriers in Organic-Field Effect Transistors

有机场效应晶体管中的少数和多数电荷载流子

• 批准号: 1709479
• 负责人: Bjorn Lussem
• 金额: $ 36.03万
• 依托单位: Kent State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709479&HistoricalAwards=false
• 关键词: Minority; Majority; Charge; Carriers; Organic

AbstractNontechnical:Organic Field-Effect Transistors (OFETs) are a key technology for flexible and low-cost electronics used e.g. for wearable electronics or flexible displays. However, OFETs are facing severe obstacles that delay their commer-cialization. Doping of organic semiconductors opens a new perspective on the OFET technology. This additional degree of freedom allows to realize new device concepts and to overcome current limitations of the OFET tech-nology. To take full advantage of the benefits of doping for OFETs, current doping ratios in the range of 0.1-1% have to be reduced significantly. The project addresses this challenge. Doping processes will be optimized to re-duce the doping level into the sub-100 ppm range. At these ultra-low doping concentrations, the influence of dop-ing on transistor behavior will be studied thoroughly: a) A quantitative model will be developed to describe charge carrier accumulation and depletion in doped organic transistors; b) Generation of minority charge carriers at ul-tralow doping concentrations will be studied; c) A new device concept - the organic tunnel field-effect transistor - will be realized, and its potential will be evaluated.To broaden the impact of the project, additional measures will be taken to increase the participation of minority students. Summer projects will be offered, which will provide undergraduate students from underrepresented groups with the opportunity to learn about experimental research and to inform them about potential choices for graduate school. Furthermore, research projects will be offered to local high-school students through the college credit plus program, and graduate students will be trained in a highly interdisciplinary field.Technical:Doping organic semiconductors provides a new dimension in the design of OFETs and bears the potential of ena-bling new device concepts with increased performance. In light of these prospects, the research goal of this project is to study the influence of doping on OFETs and to provide an improved understanding of majority and minority charge carrier generation and recombination in doped OFETs. To reach this aim, the following objectives are pursued: a) to develop a consistent and experimentally validated model describing majority charge carrier accumulation and depletion in doped organic transistors; b) to study mi-nority charge carrier dynamics in doped organic transistors and clarify the mechanism of minority charge carrier generation and recombination; and c) to leverage on the potential of doping and realize vertical organic tunnel field-effect transistors (VOTFETs).Doping organic transistors necessitates the use of much lower doping concentrations as commonly used in organic devices. In this project, a rotating shutter system capable of controlling doping concentrations in the sub 100 ppm regime is introduced, which opens a new regime of doping. The influence of doping on the flatband, threshold, and pinch-off voltage at these ultra-low doping concentrations is studied by capacitance vs. voltage measurements, photoelectron spectroscopy, and transistor characterization. Minority charge carrier generation is studied in organ-ic metal-oxide-semiconductor structures and organic transistors, whereas the lifetime and diffusion length of mi-nority charge carriers are characterized in p-n-i-p structures. The operation mechanism of VOTFETs will be stud-ied by systematic device variations. In particular, the tunnel injection mechanism will be validated by an increase in the thickness of the intrinsic semiconductor layer.These experiments have the potential to advance the knowledge in the field: a) The mechanism of minority charge carrier generation will be clarified; b) An analytical model describing the influence of the flatband voltage on the threshold and pinch-off voltage will be tested; c) A detailed understanding of minority charge carrier diffusion will be developed and it will be studied how the lifetime of minority charge carriers depends on the doping con-centration and temperature; d) A new analytical solution describing current saturation in doped OFETs will be verified.

摘要非技术性：有机场效应晶体管（OFFET）是用于可穿戴电子产品或柔性显示器等柔性和低成本电子产品的关键技术。然而，外国直接投资管理局面临严重障碍，推迟了它们的企业化进程。有机半导体的掺杂为OFET技术开辟了新的前景。这种额外的自由度允许实现新的器件概念并克服OFET技术的当前限制。为了充分利用OFFEX掺杂的益处，必须显著降低0.1-1%范围内的电流掺杂比。 该项目旨在应对这一挑战。掺杂工艺将被优化，以将掺杂水平降低到低于100 ppm的范围。在这些超低掺杂浓度下，将彻底研究掺杂对晶体管行为的影响：a）将开发一个定量模型来描述掺杂有机晶体管中电荷载流子的积累和耗尽; B）将研究超低掺杂浓度下少数电荷载流子的产生;（c）将实现一种新的器件概念-有机隧道场效应晶体管，并将评估其潜力，为扩大该项目的影响，将采取更多措施，增加少数民族学生的参与。将提供暑期项目，这将为来自代表性不足群体的本科生提供了解实验研究的机会，并告知他们研究生院的潜在选择。此外，还将通过大学学分计划向当地高中生提供研究项目，并在高度跨学科的领域培养研究生。技术：掺杂有机半导体为OFFEs的设计提供了一个新的维度，并具有实现新器件概念和提高性能的潜力。鉴于这些前景，本项目的研究目标是研究掺杂对OFFEs的影响，并提供掺杂OFFEs中多数和少数电荷载流子产生和复合的更好理解。为了达到这一目的，我们的目标是：（a）建立一个描述掺杂有机晶体管中多数载流子积累和耗尽的一致的和实验验证的模型：（B）研究掺杂有机晶体管中少数载流子的动力学，阐明少数载流子产生和复合的机理;以及c）利用掺杂的潜力并实现垂直有机隧道场效应晶体管（VOTFFET）。掺杂有机晶体管需要使用比有机器件中常用的低得多的掺杂浓度。在该项目中，引入了一种能够将掺杂浓度控制在100 ppm以下的旋转快门系统，这开启了一种新的掺杂方式。通过电容-电压测量、光电子能谱和晶体管表征研究了掺杂对这些超低掺杂浓度下的平带、阈值和夹断电压的影响。研究了有机金属氧化物半导体结构和有机晶体管中少数载流子的产生，而在p-n-i-p结构中少数载流子的寿命和扩散长度是表征的。将通过系统的器件变化来研究VOTFFET的运行机理。这些实验有可能推进该领域的知识：a）阐明少数电荷载流子产生的机制; B）测试描述平带电压对阈值和夹断电压影响的分析模型; c）详细了解少数电荷载流子的扩散，研究少数电荷载流子的寿命与掺杂浓度和温度的关系; d）验证描述掺杂OFFEs中电流饱和的新解析解。

项目成果

Organic Doping at Ultralow Concentrations

• DOI: 10.1002/adom.202100089
• 发表时间: 2021-04-24
• 期刊: ADVANCED OPTICAL MATERIALS
• 影响因子: 9
• 作者: Krishnan, Raj Kishen Radha;Liu, Shiyi;Lussem, Bjorn
• 通讯作者: Lussem, Bjorn

Doped N‐Type Organic Field‐Effect Transistors Based on Faux‐Hawk Fullerene

• DOI: 10.1002/aelm.201900109
• 发表时间: 2019-05
• 期刊: Advanced Electronic Materials
• 影响因子: 6.2
• 作者: Shiyi Liu;Nicholas J. DeWeerd;B. Reeves;Long K. San;Drona Dahal;Raj Kishen Radha Krishnan;S. Strauss;O. Boltalina;B. Lüssem

67-1: Invited Paper: Doped Organic Transistors - Increased Stability and Reproducibility for Active Matrix Displays

67-1：特邀论文：掺杂有机晶体管 - 提高有源矩阵显示器的稳定性和再现性

• DOI: 10.1002/sdtp.12241
• 发表时间: 2018
• 期刊: SID Symposium Digest of Technical Papers
• 作者: Liu, Shiyi;Al-Shadeedi, Akram;Kaphle, Vikash;Lüssem, Björn
• 通讯作者: Lüssem, Björn

Analytic Device Model of Organic Field-Effect Transistors with Doped Channels

掺杂沟道有机场效应晶体管的分析器件模型

• DOI: 10.1021/acsami.0c12534
• 发表时间: 2020
• 期刊: ACS Applied Materials & Interfaces
• 影响因子: 9.5
• 作者: Liu, Shiyi;Radha Krishnan, Raj Kishen;Dahal, Drona;Lüssem, Björn
• 通讯作者: Lüssem, Björn

Vertical Organic Tunnel Field-Effect Transistors

垂直有机隧道场效应晶体管

• 发表时间: 2019
• 期刊: ACS applied electronic materials
• 影响因子: 4.7
• 作者: Liu, Shiyi;Tietze, Max;Al-Shadeedi, Akram;Kaphle, Vikash;Keum, Changmin;Lussem, Bjorn
• 通讯作者: Lussem, Bjorn