Toward Opto-phononics: photo-excitation and control of electrons and phonons in nanostructures

当一束光照射在大块导体上时，产生的热量会扩散到很大的区域。与此形成鲜明对比的是，申请人的研究小组最近发现了一种被称为“热陷阱”的现象，该现象由被称为碳纳米管森林的纳米结构导体中的光致热的强烈局部化组成。照明点可以作为热绝缘体，但仍保持导电。几十年来，人们一直在寻求这种特性的组合，并对从清洁能源到信息技术的许多领域产生了深远的影响。 这一提议是建立在最近这一突破性发现的基础上的。我们将研究热阱背后的基本机制。此外，我们还将在此基础上开发两种新型设备，每种设备都利用了热阱的某些方面。 热的强烈局部化，防止热能损失，允许用低功率光束将照明点有效加热到极高的温度。由于该点保持导电性，这使得电子能够使用容易获得的光源（如太阳）将电子发射到真空中。在此基础上，我们将设计出世界上第一个热离子太阳能电池。这种装置在效率上可以超过现有的太阳能电池，而且可以具有固有的存储容量。因此，它可能对可再生能源技术产生重大影响。 在热阱中，光似乎可以调节声子（与热振动相关的粒子）的流动。基于这一特性，我们将创造出世界上第一个光控热晶体管。电子晶体管是当今信息技术革命的核心。我们的设备可以在未来的信息技术中发挥类似的核心作用，除了电信号之外还使用热信号。 这一努力将为一个新的研究领域铺平道路：“光声子学。"

When a beam of light strikes a bulk conductor, the generated heat spreads to a wide area. In stark contrast, the applicant's research group has recently discovered a phenomenon called "Heat Trap," consisting of strong localization of light-induced heat in nanostructured conductors known as carbon nanotube forests. The illuminated spot can act as a thermal insulator, yet remain electrically conductive. This combination of properties has been sought for decades and has far-reaching implications for many areas ranging from clean energy to information technologies. This proposal builds on this recent ground-breaking finding. We will investigate the fundamental mechanisms behind Heat Trap. In addition, we will pursue two novel devices based on it, each capitalizing on certain aspects of Heat Trap. The strong localization of heat, preventing loss of thermal energy, allows the efficient heating of the illuminated spot to extremely high temperatures with a low-power beam of light. Since the spot retains electrical conductivity, this enables thermionic emission of electrons into vacuum using readily-available light sources like the sun. Based on this, we will engineer the world's first Thermionic Solar Cell. This device could outperform existing solar cells in efficiency and, moreover, could have inherent storage capacity. It could thus have a major impact in renewable energy technologies. In Heat Trap, it appears that light can regulate the flow of phonons (particles associated with thermal vibrations). Based on this property, we will create the world's first optically-controlled thermal transistor. The electronic transistor is at the core of today's information technology revolution. Our device could play a similarly central role in future information technologies, using thermal signals in addition to electric signals. This effort will pave the way toward a new field of research: "Opto-phononics."