Photo-Induced Bandgap Engineering of Metal Halide Perovskite Quantum Dots In Flow.

Jha, Pragyan; Mukhin, Nikolai; Ghorai, Arup; Morshedian, Hamed; Canty, Richard B; Delgado-Licona, Fernando; Brown, Emily E; Pyrch, Austin J et al. · Adv Mater · 2025

basic_science · Level V

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Abstract

Over the past decade, lead halide perovskite (LHP) nanocrystals (NCs) have attracted significant attention due to their tunable optoelectronic properties for next-generation printed photonic and electronic devices. High-energy photons in the presence of haloalkanes provide a scalable and sustainable pathway for precise bandgap engineering of LHP NCs via photo-induced anion exchange reaction (PIAER) facilitated by in situ generated halide anions. However, the mechanisms driving photo-induced bandgap engineering in LHP NCs remain not fully understood. This study elucidates the underlying PIAER mechanisms of LHP NCs through an advanced microfluidic platform. Additionally, the first instance of a PIAER, transforming CsPbBr<sub>3</sub> NCs into high-performing CsPbI<sub>3</sub> NCs, with the assistance of a thiol-based additive is reported. Utilizing an intensified photo-flow microreactor accelerates the anion exchange rate 3.5-fold, reducing material consumption 100-fold compared to conventional batch processes. It is demonstrated that CsPbBr<sub>3</sub> NCs act as photocatalysts, driving oxidative bond cleavage in dichloromethane and promoting the photodissociation of 1-iodopropane using high-energy photons. Furthermore, it is demonstrated that a thiol-based additive plays a dual role: surface passivation, which enhances the photoluminescence quantum yield, and facilitates the PIAER. These findings pave the way for the tailored design of perovskite-based optoelectronic materials.