In-Depth Study of Ambipolar Charge-Transport Regime through External Triggers and Gas Sensing.

Ambipolar devices are a hot topic in research tables due to their unique advantage in reducing the size of the electrical system and enhancing its efficiency. Here, we report a bilayer heterojunction device constructed using octafluoro-vanadyl-phthalocyanine (VOFPc) and lutetium bisphthalocyanine (LuPc), which exhibits both p- and n-type behaviors under oxidizing (NO and O) and reducing gas (NH) species depending on the humidity level and temperature variations. The initial polarity of the device is identified as n-type by measuring a current decrease under oxygen exposure.

Ambipolar Heterojunction Sensors: Another Way to Detect Polluting Gases.

Gas sensors based on ambipolar materials offer significant advantages in reducing the size of the analytical system and enhancing its efficiency. Here, bilayer heterojunction devices are constructed using different octafluorinated phthalocyanine complexes, with Zn and Co as metal centers, combined with a lutetium bisphthalocyanine complex (LuPc). Stable p-type behavior is observed for the ZnFPc/LuPc device under both electron-donating (NH) and -oxidizing (NO and O) gaseous species, while the CoFPc/LuPc device exhibits n-type behavior under reducing gases and p-type behavior under oxidizing gases.

Modulating the Electrical Properties of Organic Heterojunction Devices Based On Phthalocyanines for Ambipolar Sensors.

Although ambipolar materials are highly studied in organic electronics, they are rarely used in gas sensors. In the present work, we studied ammonia sensing on organic heterojunctions in a bilayer configuration composed of octachlorinated metallophthalocyanines (M(ClPc); M: Co, Cu, and Zn) as a sublayer and lutetium bis-phthalocyanine (LuPc) as a top layer. Despite the small effect of metal atom in M(ClPc) on the device current and the interfacial energy barrier, a strong effect on the NH sensing behavior was found such that Co(ClPc)-, Cu(ClPc)-, and Zn(ClPc)-based devices exhibited -type, -type, and ambipolar charge carrier transport, respectively.

Multidrug-Resistant Tuberculosis in Burkina Faso from 2006 to 2017: Results of National Surveys.

Setting: A survey of the prevalence of drug-resistant tuberculosis (DR-TB) in new and previously treated patients (PTPs) was performed in Burkina Faso from 2016 to 2017.

Design: In this cross-sectional survey, a structured questionnaire was administered to eligible smear-positive patients in all 86 diagnostic and treatment centers of the country to collect their socio-demographic characteristics and medical histories. Their sputa were tested using the (MTB/RIF) Xpert assay.