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Conjugated polymers exhibit significant potential for use in gas sensors owing to their flexibility and straightforward preparation. However, the performance of organic gas sensors based on such materials is currently suboptimal owing to their poor charge‐transport properties and limited selectivity. To address this limitation, a novel strategy that involves blending a chemically modified metal–organic framework (MOF) material, UiO‐66, with a conjugated polymer is developed. The MOF porous material is chemically modified with polar nitrogen‐containing functional groups (amino and nitro groups) to create gas molecule adsorption sites. To evaluate the impact of these modifications on the sensing performance, experiments that combined the sensing performance with a density functional theory simulation are conducted. The findings reveal that gas sensors fabricated using an amine‐functionalized MOF blended with conjugated polymers exhibit significantly higher sensitivity than home polymer devices, the sensing performance of the UiO‐66‐NH2/P3HT blend film improved by a factor of two with a sensitivity of ≈2%/ppm and an LOD of 0.001 ppt. Additionally, these devices exhibit exclusive NO2‐sensing performance for other gases such as CO2 and SO2. [ABSTRACT FROM AUTHOR]

Abstract Conjugated polymers exhibit significant potential for use in gas sensors owing to their flexibility and straightforward preparation. However, the performance of organic gas sensors based on such materials is currently suboptimal owing to their poor charge‐transport properties and limited selectivity. To address this limitation, a novel strategy that involves blending a chemically modified metal–organic framework (MOF) material, UiO‐66, with a conjugated polymer is developed. The MOF porous material is chemically modified with polar nitrogen‐containing functional groups (amino and nitro groups) to create gas molecule adsorption sites. To evaluate the impact of these modifications on the sensing performance, experiments that combined the sensing performance with a density functional theory simulation are conducted. The findings reveal that gas sensors fabricated using an amine‐functionalized MOF blended with conjugated polymers exhibit significantly higher sensitivity than home polymer devices, the sensing performance of the UiO‐66‐NH2/P3HT blend film improved by a factor of two with a sensitivity of ≈2%/ppm and an LOD of 0.001 ppt. Additionally, these devices exhibit exclusive NO2‐sensing performance for other gases such as CO2 and SO2.

The synthesis and characterization of a series of [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) molecules disubstituted by hydroxy aliphatic chains in positions 2 and 7 (BTBT‐CnOH), where the intralayer molecular stacking alternates between a classical and an inverted herringbone mode as a function of whether the alkyl sides chains have an even or an odd number of carbon atoms are reported. This odd–even effect does not only affect the interlayer distance of the lamellar structures and the melting points, but also the electronic properties. The BTBT‐CnOH odd series develops a classical herringbone pattern with edge‐to‐edge S⋯S interaction chains linked together by face‐to‐edge S⋯S interaction chains with 2D mobility. However, the even series has only edge‐to‐edge interactions in an inverted herringbone organization and thus only a 1D conducting character. These two types of herringbone patterns have different field effect transistor characteristics and mobilities, those of the odd members being systematically higher than their even neighbors. This is the first example of an odd–even effect impacting the electronic properties of an organic semiconductor. [ABSTRACT FROM AUTHOR]

To enhance electron injection in n-type organic field-effect transistors (OFETs), nonconjugated polyelectrolyte (NPE) layers are interposed between a [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) layer and Au electrodes. A series of NPEs based on an ethoxylated polyethylenimine backbone with various counterions, including Cl−, Br−, and I−, improve electron mobilities up to ≈10−2 cm2 V−1 s−1 and yield on-off ratios ( Ion/ Ioff) of 105 in PCBM OFETs. Ultraviolet photoelectron spectroscopy reveals that all of the NPEs lead to reduced electron injection barriers (φe) at the NPE/metal interface; this reduction in φe is consistent with dipole formation or n-type doping at the electrode interface. Absorption measurements of PCBM films treated with NPEs are consistent with n-doping of the PCBM. Regardless of the type of anion, thick NPE layers lead to high conductivity in the films independent of gate bias, whereas thin NPE layers lead to dramatically improved electron injection and performance. These results demonstrate that thin polyelectrolyte layers can be used to achieve controlled interfacial doping in organic semiconductors. Furthermore, this study provides valuable information about the function of NPEs, which may be exploited to improve device performance and to design new materials for future use in optoelectronic devices. [ABSTRACT FROM AUTHOR]

In article number 1700184, Jung Hwa Seo, Bright Walker, and co‐workers present cationically charged polyelectrolytes that are used to promote controlled, n‐type doping at exposed interfaces in PCBM transistors. These lead to efficient electron injection from high work function Au electrodes and excellent transistor performance. [ABSTRACT FROM AUTHOR]