Collaborative Research: Amplifying the Efficiency of Tungsten Disulfide (WS2) Thermoelectric Devices

非技术性：美国每年生产的能源中有多达一半作为废热损失。将废热转化为电能可以大大提高能源效率，并大幅减少温室气体排放。热电（TE）设备将温差转换为电能，并有可能彻底改变国家的能源组合。理想的热电材料导电，但不导热。金属两者都导电，而绝缘体两者都不导电。该项目通过使用一种新的策略来掺杂二维（2D）半导体二硫化钨来挑战这种二分法。我们将提高其热电系数以最大化输出电压，增加电导率以最小化损耗，并降低热导率以保持较大的温差。拟议的研究将导致有效的设备余热回收。这项工作还将使高性能2D晶体管，低功耗存储设备和纳米级开关的热管理。该团队将与当地社区密切合作，鼓励来自各种背景的学生参与工程职业，并培养对纳米技术的兴趣。拓展工作将包括实验室演示、暑期实习和职业研讨会。技术：本项目的目标是通过电化学插层设计二维二硫化钨（WS 2）器件的电、热和热电性能，以提高其面内热电效率。WS 2由于其大的原子质量（低热导率）、小的带隙（高电导率）和高塞贝克系数（Seebeck coefficient）而最近成为有希望的TE候选物。然而，优化所有材料特性以最大化其TE效率并掺杂该2D材料以创建TE器件所需的p型和n型对仍然具有挑战性。在这项工作中，我们将：（1）通过阴离子和阳离子插层实现二维材料中的p型和n型掺杂;（2）通过掺杂优化WS 2的面内功率因数;（3）通过插层物的声子散射降低WS 2的面内热导率。从根本上讲，该项目将研究2D材料中的电，离子和热传输。实际上，这项工作将为广泛使用热电设备来消除电子和人体等来源的热量铺平道路。这项工作还将开发一种用于2D材料的掺杂方法，解决2D电子产品中的关键问题，如低驱动电流和接触电阻差。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical:As much as half of US energy production each year is lost as waste heat. Converting waste heat into electricity could improve energy efficiency dramatically and sharply reduce greenhouse gas emissions. Thermoelectric (TE) devices convert temperature differences into electrical power and have the potential to revolutionize the nation's energy portfolio. An ideal thermoelectric material conducts electricity, but not heat. Metals conduct both, whereas insulators conduct neither. This project challenges this dichotomy by using a novel strategy to dope tungsten disulfide, a two-dimensional (2D) semiconductor. We will enhance its thermoelectric coefficient to maximize the output voltage, increase the electrical conductivity to minimize losses, and lower the thermal conductivity to maintain a large temperature difference. The proposed research will lead to efficient devices for waste heat recovery. This work will also enable high-performance 2D transistors, low-power memory devices, and nanoscale switches for thermal management. The team will work closely with local communities to encourage participation by students from all backgrounds in engineering careers and foster interest in nanotechnology. Outreach efforts will include lab demonstrations, summer internships, and career workshops.Technical:The goal of this project is to improve the in-plane thermoelectric efficiency of two-dimensional tungsten disulfide (WS2) devices through engineering their electrical, thermal, and thermoelectric properties via electrochemical intercalation. WS2 has recently emerged as a promising TE candidate due to its large atomic mass (low thermal conductivity), small bandgap (high electrical conductivity), and high Seebeck coefficient. However, it remains challenging to optimize all of the material properties to maximize its TE efficiency and to dope this 2D material to create the p- and n-type pairs needed for TE devices. In this work, we will: (1) achieve p- and n-type doping in 2D materials via anion and cation intercalations; (2) optimize the in-plane power factor of WS2 through doping; (3) reduce the in-plane thermal conductivity of WS2 via phonon scattering by intercalants. Fundamentally, this project will study electrical, ionic, and thermal transport in 2D materials. Practically, this work will pave the way for the wide use of thermoelectric devices to scavenge heat from sources such as electronics and the human body. This work will also develop a doping method for 2D materials, addressing critical issues in 2D electronics such as low drive current and poor contact resistance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.