Highly-sensitive organic field effect transistor sensors for dual detection of humidity and NO2

Review of recent advances and sensing mechanisms in solid-state organic thin-film transistor (OTFT) sensors

“…Among strong redox gases, the quantification of NH 3 , H 2 S, NO/NO 2 and SO 2 are particularly useful since they are industrially produced chemicals or pollutants generated as a result of manufacturing processes or emitted in automobile combustion engines. 36,37 A number of organic semiconductors incorporated into OTFTs have been reported to be sensitive to NH 3 , [38][39][40][41][42][43][44] H 2 S, [45][46][47][48] NO 2 , [49][50][51][52][53][54][55] and SO 2 . 56 OTFT redox gas sensors often offer advantages over metal-oxide-based sensors owing to their less strict operational requirements.…”

“…5C). 55 Transistors were fabricated with a VOPc thickness from 5 nm to 20 nm and showed a high dependence on humidity with a V T shift of 0.59 V %RH À1 . The thickness yielding the best response to NO 2 was a 10 nm-thick film with a responsivity of 178% ppm À1 , a theoretical LOD of 125.2 ppb and a S of 0.54 ppm À1 .…”

“…Isolating the influence molecular template layers and WEG on the performance of OTFT sensors has been scarcely reported even though p -6P has been utilized for these applications in the literature. 52,55 Wang et al recently reported OTFT sensors based on α-sexithiophene (α-6T) as the organic semiconductor fabricated with and without a p -6P templating layer to investigate the influence of the template on performance (Fig. 11A).…”

“…Thermally induced morphology changes demonstrated in organic semiconductor films make thermal annealing an attractive technique towards tuning the S of OTFT sensors. While work by L. J. Wang and coworkers employed thermal annealing in the optimization of OTFT sensors for the detection of NO 2 and humidity, 55 the true effect of thermal annealing on the sensitivity of OTFT sensors is scarce. Yang et al thermally annealed OTFT-based sensors with a DPP-bithiophene conjugated polymer containing tert-butoxycarboxyl groups, pDPPBu-BT, as the active layer at 240 °C, which transformed the tert-butoxycarboxyl groups into carboxylic acid groups, reducing the solubility of the material and increasing its reactivity with NH 3 .…”

Solution-processed filamentous copper phthalocyanine films for enhanced NO2 gas sensing at room temperature

“…Organic field effect transistor (OFET) gas sensors, as a new generation of gas sensors, not only have the characteristics of a simple preparation process, low cost, light weight and good flexibility, but also have the outstanding characteristics of rapid start-up at room temperature, sensing and high amplification, simple portability, high sensitivity and intelligent electronic applications. [1][2][3] Organic semiconductors (OSCs) are the key component of OFETs, which directly affect the performance and application field of OFETs. [4][5][6] For OFETs, the conducting channels are usually concentrated within a few molecular layers at the bottom of the OSCs, near the interface between the OSCs and the dielectric layers.…”