Solution-processed laser diodes utilizing colloidal quantum wells

利用纳米墨水打印激光二极管的前景被认为是医学成像、柔性衬底光子学和光通信领域的突破性范例。基于纳米颗粒的激光器比传统的固态激光器便宜得多，并且提供了更广泛的可获得的颜色范围。可打印激光器的一个臭名昭著的问题是，随着激光功率的增加，半导体纳米颗粒的光学输出急剧下降。这个问题对这些设备的寿命和效率都有负面影响。拟议的项目旨在通过开发一种新型的半导体纳米颗粒来解决这个问题，这种纳米颗粒被设计成能够承受激光元件的高功率条件。拟议的创新将依靠球状分层纳米颗粒几何结构(胶体量子井)来实现入射功率的最佳重新分配，从而防止光能损失和热损害。该项目将研究如何将这些纳米颗粒与电极对接，以及如何确保激光组件中的光有效传播。胶体量子阱激光二极管的成功展示将使人们能够以更低的成本制造光子电路，提供按需可调的发射颜色，并表现出与各种衬底的良好兼容性。作为该项目不可或缺的一部分，PI将领导一项多方面的教育工作，包括：(I)促进包容性的本科生研究；(Ii)-开发一门新的、高水平的纳米光子学课程，最近获得大学行政部门的批准；(Iii)-为本科生主持年度研究体验计划；以及(Iv)-通过项目的合作性质促进对研究生的跨学科培训。技术描述：由半导体量子点(QD)溶液制成的激光二极管有可能发展成为传统外延激光器的一种经济和颜色可调的替代方案。量子点激光技术发展面临的主要障碍是，当每个粒子产生一个以上的电子-空穴对(激子)时，受激辐射的效率急剧下降。捕获在小体积量子点中的多个激子进行快速俄歇复合，随着电泵浦的增加而有效地滚落。该项目旨在解决这个问题，用球形量子阱取代传统的半导体量子点，球形量子阱的几何结构经过优化，可以通过相互排斥来抑制多激子的俄歇衰变。沿着这些思路，该项目将专注于胶体量子井的化学合成，并解决器件设计的方方面面，包括发光层的溶液处理、优化电气接口和制造共振激光腔。预计，胶体量子阱中俄歇复合的强烈抑制将使溶液处理激光器中光放大所需的电流密度显著降低。同时，量子井的低维性质将允许在可见光和红外(电信)光谱窗口中连续调谐激光发射。最终，这项调查将寻求展示与可印刷光子电路集成的具有竞争力的解决方案加工激光二极管。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The prospect of printing laser diodes from nanoparticle inks has been regarded as a breakthrough paradigm in fields of medical imaging, flexible substrate photonics, and optical communications. Nanoparticle-based lasers are considerably less expensive than traditional solid-state counterparts and offer a far broader range of accessible colors. A notorious problem of printable lasers concerns a sharp decline in the optical output of semiconductor nanoparticles with increasing laser power. This issue negatively affects both the longevity and the efficiency of these devices. The proposed project aims to address this problem by developing a novel class of semiconductor nanoparticles, which is designed to withstand high-power conditions of a lasing element. The proposed innovation will rely on a spherically-layered nanoparticle geometry (colloidal quantum wells) to achieve an optimal redistribution of an incident power, thus preventing optical energy losses and thermal damage. The project will investigate how to interface these nanoparticles with electrodes and how to ensure an efficient light propagation in the laser assembly. The successful demonstration of colloidal quantum-well laser diodes will allow photonic circuits to be fabricated at lower costs, offer an on-demand tunable emission colors, and exhibit an excellent compatibility with a wide variety of substrates. As an integral part of this project, the PI will lead a multi-faceted educational effort that will involve: (i) – fostering an inclusive undergraduate research, (ii) – developing a new, upper-level nanophotonics course, recently approved by the university administration, (iii) – hosting an annual research experience program for undergraduates, and (iv) - providing an interdisciplinary training of graduate students, facilitated by the collaborative nature of the project. TECHNICAL DESCRIPTION: Lasers diodes processed from solutions of semiconductor quantum dots (QD) can potentially evolve as an economical and color-tunable alternative to conventional epitaxial lasers. The main obstacle facing the development of QD laser technology concerns a sharp decline in the efficiency of stimulated emission when more than one electron-hole pair (exciton) per particle is created. Multiple excitons trapped within a small volume of a QD undergo fast Auger recombination, causing an efficiently roll-off with increasing electrical pumping. The proposed project aims to address this issue by replacing traditional semiconductor quantum dots with spherical quantum wells, which geometry is optimized for suppressing Auger decay of multiple excitons through their mutual repulsion. Along these lines, the project will focus on chemical synthesis of colloidal quantum wells and address all aspects of device design, including solution-processing of the light-emitting layer, optimizing electrical interfaces, and fabricating the resonant laser cavity. It is expected that a strong suppression of Auger recombination in colloidal quantum wells will enable a significant reduction in the current densities needed for light amplification in solution-processed lasers. Meanwhile, low-dimensional nature of quantum wells will allow tuning the laser emission continuously throughout visible and infrared (telecom) spectral windows. Ultimately, this investigation will seek to demonstrate competitive solution-processed laser diodes for integration with printable photonic circuits.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.