Halide Perovskite glues activate two-dimensional covalent organic framework crystallites for selective NO₂ sensing

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Two-dimensional covalent organic frameworks (2D COFs) possess properties suitable for gas sensing, including large surface areas and active sites.
• However, their practical application is limited by poor inter-crystallite conductivity in insoluble micro-crystallite forms.

Purpose of the Study:

• To enhance the conductivity of 2D COF films for improved gas sensing performance.
• To demonstrate the use of halide perovskites as an effective 'electric glue' for 2D COF materials.

Main Methods:

• Fabrication of 2D COF films integrated with halide perovskites.
• Electrical conductivity measurements before and after perovskite integration.
• Gas sensing experiments for nitrogen dioxide (NO2) detection.
• Characterization using resonant microcantilever, Monte Carlo, DFT, and sum-frequency generation analyses.

Main Results:

• Halide perovskites improved the conductivity of 2D COF films by two orders of magnitude.
• The enhanced conductivity enabled highly selective and sensitive detection of NO2.
• Mechanism confirmed electron enrichment and transfer from 2D COFs to NO2 molecules.

Conclusions:

• Halide perovskites effectively overcome conductivity limitations in polycrystalline 2D COF films.
• This approach facilitates the use of 2D COFs in various semiconductor devices.
• Potential applications include sensors, resistors, memristors, and field-emission transistors.