Controllable gas selectivity at room temperature based on Ph5T2-modified CuPc nanowire field-effect transistors

A dinaphtho[3,4-d:3 ',4 '-d '] benzo[ 1,2-b: 4,5-b '] dithiophene (Ph5T2)-modified copper phthalocyanine (CuPc) single crystal nanowire field-effect transistor (FET) with gas dielectric was fabricated as an organic gas sensor. This device exhibits the high response and the excellent controllable selectivity at room temperature. Its detection limit for NO2, NO, and H2S is down to sub-ppm level. Prior to surface modification, the CuPc nanowire FET shows the response as high as 1088% to 10 ppm H2S, but only 97.5% to 10 ppm NO2. After Ph5T2 modification, the response to 10 ppm H2S is decreased by one order of magnitude, but is dramatically improved up to 460% to 10 ppm NO2. The responses towards H2S and NO2 respectively for pristine and the modified sensor are higher than those of most reported organic sensors. The gas-sensing results reveal that Ph5T2 modification can transform the selectivity of the sensor from H2S to NO2. The controllable modulation of gas selectivity is related to the formed organic heterojunctions between CuPc and Ph5T2, where the hole carriers of CuPc nanowire are modulated by these heterojunctions, resulting in the changed adsorption behavior towards different gases. (C) 2017 Elsevier B.V. All rights reserved.