High Sensitivity and Ultra‐Broad‐Range NH 3 Sensor Arrays by Precise Control of Step Defects on The Surface of Cl 2 ‐Ndi Single Crystals

Bin Lu, Matthias Stolte, Dong Liu, Xiaojing Zhang, Lihui Zhao, Liehao Tian, C. daniel Frisbie, Frank Würthner, Xutang Tao, Tao He

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Vapor sensors with both high sensitivity and broad detection range are technically challenging yet highly desirable for widespread chemical sensing applications in diverse environments. Generally, an increased surface-to-volume ratio can effectively enhance the sensitivity to low concentrations, but often with the trade-off of a constrained sensing range. Here, an approach is demonstrated for NH3 sensor arrays with an unprecedentedly broad sensing range by introducing controllable steps on the surface of an n-type single crystal. Step edges, serving as adsorption sites with electron-deficient properties, are well-defined, discrete, and electronically active. NH3 molecules selectively adsorb at the step edges and nearly eliminate known trap-like character, which is demonstrated by surface potential imaging. Consequently, the strategy can significantly boost the sensitivity of two-terminal NH3 resistance sensors on thin crystals with a few steps while simultaneously enhancing the tolerance on thick crystals with dense steps. Incorporation of these crystals into parallel sensor arrays results in ppb–to–% level detection range and a convenient linear relation between sheet conductance and semi-log NH3 concentration, allowing for the precise localization of vapor leakage. In general, the results suggest new opportunities for defect engineering of organic semiconductor crystal surfaces for purposeful vapor or chemical sensing.

Original languageEnglish (US)
Article number2308036
JournalAdvanced Science
Issue number14
StatePublished - Apr 10 2024

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© 2024 The Authors. Advanced Science published by Wiley-VCH GmbH.

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