Autonomous lab helps find quantum dots with highest yield in hours

What does SmartDope do?

Quantum dots have a high research interest since they can be used to fast-track a large spectrum of applications. However, the process of doping is time-consuming and tedious, and it can take years to develop a doped material specifically for an application.

The research team led by Milad Abolhasani, an associate professor of chemical engineering at NCSU designed an autonomous lab where the process can be carried out at a smaller scale but a quicker pace and deliver results in a matter of hours or even days, saving valuable time.

To begin, the research team instructs the SmartDope system on the intended goal of the process and the precursor materials that are available to work with. Following this, the system runs experiments autonomously in a continuous flow reactor using extremely small amounts of chemicals.

The system itself is capable of manipulating variables such as amounts of precursors mixed, the temperature at which the mixing happens, or the reaction time. SmartDope is also designed to carry out a basic analysis of the doped material created as it leaves the system.

How well does SmartDope work?

The NCSU researchers tasked the SmartDope system with developing quantum dots with the highest "quantum yield," meaning these dots had to produce the highest ratio of photons emitted to photons absorbed. The autonomous lab was also able to characterize the optical properties of the material created and used machine learning to understand the results of its experiments and improve them.

One reason why the researchers assigned this experiment to SmartDope was that quantum doping for the highest quantum yield had been done before and set a record at 130 percent. This means that quantum dots that emit 1.3 photons for every photon absorbed already exist. The SmartDope system ran for just one day before it arrived at quantum dots with yields of 158 percent.

"That’s a significant advance, which would take years to find using traditional experimental techniques," said Abolhasani in the press release. "We found a best-in-class solution for this material in one day. This work showcases the power of self-driving labs using flow reactors to rapidly find solutions in chemical and material sciences," he added.

The research findings were published in the journal Advanced Energy Materials.

Abstract:

Metal cation-doped lead halide perovskite (LHP) quantum dots (QDs) with photoluminescence quantum yields (PLQYs) higher than unity, due to quantum cutting phenomena, are an important building block of the next-generation renewable energy technologies. However, synthetic route exploration and development of the highest-performing QDs for device applications remain challenging. In this work, Smart Dope is presented, which is a self-driving fluidic lab (SDFL), for the accelerated synthesis space exploration and autonomous optimization of LHP QDs. Specifically, the multi-cation doping of CsPbCl3 QDs using a one-pot high-temperature synthesis chemistry is reported. Smart Dope continuously synthesizes multi-cation-doped CsPbCl3 QDs using a high-pressure gas-liquid segmented flow format to enable continuous experimentation with minimal experimental noise at reaction temperatures up to 255°C. Smart Dope offers multiple functionalities, including accelerated mechanistic studies through digital twin QD synthesis modeling, closed-loop autonomous optimization for accelerated QD synthetic route discovery, and on-demand continuous manufacturing of high-performing QDs. Through these developments, Smart Dope autonomously identifies the optimal synthetic route of Mn-Yb co-doped CsPbCl3 QDs with a PLQY of 158%, which is the highest reported value for this class of QDs to date. Smart Dope illustrates the power of SDFLs in accelerating the discovery and development of emerging advanced energy materials.