(651g) Photo-Induced Bandgap Engineering of Metal Halide Perovskite Quantum Dots in Flow

Over the last decade, colloidal metal halide perovskite (MHP) quantum dots (QDs) have attracted significant attention because of their unique optical and optoelectronic properties, which can be tuned by varying their size, composition, and surface ligands.¹ However, significant challenges persist in precision synthesis and large scale manufacturing of these high-performing ionic nanocrystals. Utilizing a high energy photon flux as the trigger for bandgap engineering of MHP QDs offers a sustainable route for precise bandgap engineering of MHP QDs.²

In this work, we present material-efficient microfluidic technology for accelerated in-situ studies of the photo-induced bandgap engineering of MHP QDs. Leveraging process intensification enabled by miniaturization, ³ and tunable collimated light source, we rapidly investigate the effect of photon flux and solvent ratio (dihalomethane-to-toluene ratio) on the kinetics and extent of the photo-induced halide exchange reaction of MHP QDs. The developed automated microfluidic technology enables intensification of the photo-induced halide exchange reaction (3.5×) while significantly reducing the material consumption (100×) compared to the conventional batch reactors (e.g., transparent flasks). Additionally, the multimodal in-situ characterization probe integrated with the microfluidic reactor enables dynamic investigation of the photo-induced halide exchange reaction without the need for manual sampling. Specifically, we utilized the developed microfluidic technology to study bandgap engineering of cesium lead bromide (CsPbBr₃) QDs using dichloromethane as a halogen source (CsPbBr_(3-x)Cl_x), and unraveled the complex nonlinear mechanism of the photo-induced halide exchange reaction.

The developed microfluidic technology enables, for the first time, detailed mechanistic studies of the photo-induced halide exchange reactions of MHP QDs and opens the door for scalable precision nanomanufacturing of high-performing MHP QDs for applications in displays and photonic devices.

References:

1. Kovalenko, M. V., Protesescu, L. & Bodnarchuk, M. I. Properties and potential optoelectronic applications of lead halide perovskite nanocrystals. Science 358, 745–750 (2017).
2. Wong, Y.-C. et al. Color Patterning of Luminescent Perovskites via Light-Mediated Halide Exchange with Haloalkanes. Advanced Materials 31, 1901247 (2019).
3. Morshedian, H. & Abolhasani, M. Accelerated Photostability Studies of Colloidal Quantum Dots. Solar RRL 7, 2201119 (2023).