Defect-Passivated Photosensor Based on Cesium Lead Bromide (CsPbBr₃) Perovskite Quantum Dots for Microbial Detection

Area of Science:

• Materials Science
• Nanotechnology
• Biotechnology

Background:

• Perovskite quantum dots (QDs) offer unique optical properties but are susceptible to environmental degradation.
• Defects in perovskite QDs, such as halide vacancies, can significantly impact their performance.
• Developing robust passivation strategies is crucial for stable and efficient perovskite QD-based devices.

Purpose of the Study:

• To fabricate a defect-passivated photosensor using cesium lead bromide (CsPbBr3) perovskite QDs and parylene films.
• To investigate the protective and defect-passivating effects of parylene films on CsPbBr3 QDs.
• To demonstrate the application of the developed photosensor for microbial detection.

Main Methods:

• Synthesis of homogeneous CsPbBr3 perovskite QDs under thermodynamic control.
• Fabrication of a photosensor utilizing MoS2 flakes as an electron transfer layer.
• Deposition of functionalized parylene films for waterproof protection and defect passivation.
• Characterization using bandgap, crystal structure, and trap-state density analysis.
• Density functional theory (DFT) calculations to elucidate passivation mechanisms.

Main Results:

• Parylene films provided effective physical protection against water degradation.
• Functional groups in parylene successfully passivated halide vacancies in CsPbBr3 QDs, reducing trap-state density.
• DFT analysis confirmed the beneficial interaction between parylene and perovskite defects.
• The parylene-passivated QD photosensor demonstrated successful detection of *Listeria monocytogenes* and *Helicobacter pylori*.

Conclusions:

• Parylene film serves as an effective passivation layer for CsPbBr3 perovskite QDs, enhancing stability and performance.
• The developed defect-passivated QD photosensor is a promising platform for sensitive and specific microbial detection.
• This approach offers a pathway for developing robust perovskite-based sensors for biological applications.