NSF Award
2208834
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. <br/><br/>TECHNICAL DESCRIPTION: <br/>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.<br/><br/>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.
