Diketopyrrolopyrrole‐Based Semiconducting Polymer with Both Hydrophobic Alkyl and Hydrophilic Tetraethylene Glycol Chains for Monolayer Transistor and Sensing Application

Abstract

studies also suggest that the first few layers of organic/polymeric semiconductors play key roles in determining the performances of FETs. [10][11][12][13][14][15] Moreover, downscaling the film thickness to a single molecular layer is of technological interest for the realization of bottomup electronic devices. [16][17][18] In particular, monolayer organic FETs (OFETs) are beneficial for sensing applications as the binding of the respective analytes with the semiconducting monolayer is expected to affect the charge transporting. [19][20][21][22][23] Consequently, such sensors with monolayer FETs can show high sensitivity and fast response.Various approaches have been explored to fabricate FETs with ultrathin semiconducting films. These include unconventional spin-coating and formation of self-assembly monolayer on surface. [24][25][26][27][28] Langmuir deposition method is known to enable the realization of monolayers at the air/liquid interface with precision control over the molecule lateral packing density. In fact, Langmuir technique was successfully utilized to transfer monolayer thin films of organic and polymeric semiconductors onto the substrates to fabricate FETs. [29][30][31][32][33][34][35] For instance, Yli-Lahti and co-workers first reported FETs with Langmuir-Blodgett (LB) films of poly(3-hexylthicphene)/ arachidic acid, but the resulting FETs exhibited rather low charge mobilities. [34] This is probably due to the fact that the LB films contain arachidic acid which is required for the formation of the polymer LB films at air-water interface. Facchetti and Pignataro and co-workers prepared n-type monolayer FET with naphthalene diimide based polymer (P (NDI2OD-T2)) by using Langmuir-Schaefer method. [35] These conjugated polymers are basically hydrophobic, but it is known that amphiphilic molecules with both hydrophobic and hydrophilic moieties can form more ordered monolayers at the air-water interface. [36][37][38] Leclerc and co-workers studied the formation of LB monolayers at air-water interface and the transfer of the monolayers onto the substrate for the conjugated polymer with both alkyl and oligo(ethylene glycol) side chains, but the semiconducting properties of the monolayers were not addressed. [38] Functional field-effect transistors (FETs) have received increasing attention in recent years. Herein, it is demonstrated that the incorporation of hydrophilic tetraethylene glycol (TEEG) chains into the diketopyrrolopyrrole (DPP)-based semiconducting polymer (PDPP3T1) can facilitate the formation of polymeric monolayer at the air-water interface, and the resulting field-effect transistors (FETs) show sensitive and selective response toward alcohol vapor. By using the Langmuir-Schaefer method, monolayer and ultrathin films from bilayer to five-layer can be successfully prepared. Interestingly, nanopores with sizes of 50-100 nm are formed within the monolayer film, as observed by using atomic force microscopy. The monolayer FET exhibits relatively high hole mobilities up to 0.014 cm 2 V −1 s −...

Structured and functionalized organic semiconductors for chemical and biological sensors based on organic field effect transistors

“…It was demonstrated that the TEG chain not only facilitated formation of a monolayer at the air-water interface, but also enabled selective detection of alcohol vapors. 60 The OFET based on a monolayer of PDPP3T1 responded to 10 ppb alcohols (isopropanol, ethanol or methanol) in the gas phase with a relative sensitivity over 2% ppb À1 , and was able to detect ethanol of concentration down to 1 ppb with good selectivity for alcohols over other gas molecules (CO 2 , hexane, CH 2 Cl 2 , acetone, and ethyl acetate), presumably due to the stronger interactions between TEG and alcohols through hydrogen bonds. Attachment of thermally reactive tert-butoxycarboxyl groups to the same poly(diketopyrrolopyrrole-terthiophene) backbone results in pDPPBu-BT ( Fig.…”

A highly selective electron affinity facilitated H2S sensor: the marriage of tris(keto-hydrazone) and an organic field-effect transistor

“…In the case of a bilayer configuration, the preferred elements will have (i) appreciable chemical compatibility among layers, (ii) good porous structures to improve gas absorption and (iii) good stability under various ambient conditions. Some of the strategies employed to realize better-sensing performance using DPP-based OFET sensors include optimization of film thickness, 16,17,20,38 tuning the porous structures to improve the surface reactivity, 18,20,39,40 blending the polymers with materials (such as graphene oxide, 39 MoS 2 , 39 polystyrenes, 39 PBA 39 and MOF 22 ) and attaching functional groups (sulfur-based motif, 41 siloxane, 39 butoxycarboxyl, 39 tetraethyl glycol, 16 thymine 42 and naphthalene 20 ) to the side chain of polymers. However, major disadvantages include their poor stability under humidity and bias stress and the resultant failure to exhibit reproducible and reliable gas-sensing performance.…”

“…10,15 Diketopyrrolopyrrole-(DPP-)based CP semiconductors in particular are considered to be promising materials for sensing as a result of their tunable bandgap, good ambient stability, interactive functional groups and flexible electronic properties. [16][17][18][19][20][21][22] Furthermore, combining the versatile DPP molecules with rigid structures such as naphthalene, thiophene and their analogous moieties results in donor-acceptor (D-A) architectures with homogenous crystal stacking and strong pi-pi intermolecular interactions. 18,20,22 Recently, many research groups have successfully integrated the DPP-based D-A polymers on organic field-effect transistor (OFET) platforms to sense NH 3 , [23][24][25][26] NO 2 , [27][28][29] H 2 S 30,31 and various VOC molecules.…”

Naphthyl End‐Capped Terthiophene‐Based Chemiresistive Sensors for Biogenic Amine Detection and Meat Spoilage Monitoring

“…Oligo‐ and polythiophenes, along with their derivatives, are an important class of fluorescent active organic semiconductors, owing to their conjugated structures. Therefore, they have been frequently studied for sensing, especially for fluorescence sensing . For the development of chemiresistors, oligothiophenes with well‐defined structures are preferred as candidates for the sensory materials because they possess at least the following two advantages: 1) high polarizability of sulfur electrons may provide a variety of intra‐ and intermolecular interactions, which are favorable for charge transport; and 2) easy modulation of chemical and physical properties through convenient structural modification .…”

“…Therefore, they have been frequently studied for sensing,e specially for fluorescences ensing. [37][38][39][40][41] For the development of chemiresistors, oligothiophenes with well-defined structures are preferred as candidates fort he sensory materials because they possessa tl east the following two advantages: 1) high polarizability of sulfur electrons may provide av ariety of intra-and intermolecular interactions, which are favorable for charget ransport;a nd 2) easy modulation of chemical and physicalp roperties through convenient structural modification. [42][43][44] However,o ligothiophenes are photochemically and thermally unstable,w hich adds al imitation to their applications in opticalsensing.…”