Solution-processed laser diodes utilizing colloidal quantum wells

用纳米颗粒油墨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一个突破性范例。基于纳米粒子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接触颜色。随着激光功率的增加，半导体纳米粒子的光输出急剧下降，这是可打印激光器的一个臭名昭著的问题。这个问题对这些设备的寿命和效率都有负面影响。提出的项目旨在通过开发一种新型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。提出的创新将依赖于球形层状纳米粒子几何结构（胶体量子阱）来实现入射功率的最佳再分配，从而防止光学能量损失和热损伤。该项目将研究如何将这些纳米颗粒与电极结合，以及如何确保激光组件中的有效光传播。胶体量子阱激光二极管的成功演示将使光子电路以更低的成本制造，提供按需可调的发射颜色，并与各种衬底具有良好的兼容性。作为该项目的一个组成部分，PI将领导多方面的教育工作，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，最近得到了大学管理部门的批准，(iii) -为本科生举办年度研究体验计划，(iv) -为研究生提供跨学科培训，促进项目的合作性质。技术描述：由半导体量子点（QD）溶液加工而成的激光二极管有可能成为传统外延激光器的一种经济且可调颜色的替代品。量子点激光技术发展面临的主要障碍是当每个粒子产生多个电子-空穴对（激子）时，受激发射效率急剧下降。被困在小体积量子点内的多个激子经历快速的俄歇复合，随着电泵的增加而产生有效的滚转。提出的项目旨在通过用球形量子阱取代传统的半导体量子点来解决这个问题，球形量子阱的几何形状经过优化，可以通过相互排斥来抑制多个激子的俄歇衰变。沿着这些思路，该项目将专注于胶体量子阱的化学合成，并解决器件设计的各个方面，包括发光层的溶液处理、优化电接口和制造谐振激光腔。预计胶体量子阱中对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，量子阱的低维特性将允许在可见光和红外（电信）光谱窗口内连续调谐激光发射。最终，本研究将寻求展示具有竞争力的溶液处理激光二极管与可打印光子电路的集成。该奖项反映了美国国家科学基金会的法定使命，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。

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.