Modification of Indium Tin Oxide Surface with HCl for Source/Drain Electrodes in Organic Thin Film Transistors

Abstract

In recent years, exciting advances have been achieved in pursuing organic thin film transistors (OTFTs) with high mobility. Whereas, the economical infeasibility of Au source/drain (S/D) electrodes that are widely used in OTFTs hinders the further development of OTFTs in industry. In this study, the modified indium tin oxide (ITO) as S/D electrodes is adopted. The ITO is modified by HCl aqueous solutions, its surface work function is improved from 4.8 to 5.5 eV. By first‐principle calculations and experiments, the charge analysis shows that the Cl atom traps 0.475 electrons, which indicates that In–Cl dipoles are responsible for the increase of the surface work function, besides the HCl modification leads to In+‐Cl− bonds instead of In3+‐Cl− bonds on the ITO surface compared with the reported InCl3 modification. More encouragingly, In+‐Cl− surface is found to have higher Cl density, higher work function and higher conductivity. TIPS‐pentacene, with suitable HOMO level of 5.2 eV, is adopted as organic semiconductor, and the bar‐coating process is optimized to realize oriented films. OTFTs with maximum field‐effect mobility of 0.77 cm2 V−1 s−1 are achieved. The ITO electrodes modified by HCl can be promising in the industry.

Nanometric Surface-Selective Regulation of Au/In2O3 Nanofibers as an Exhaled H2S Chemiresistor for Periodontitis Diagnosis

“…As compared, the modification of SAMs induced more amount of O V , which is associated with the combined effect of three factors. First, the increasing amount of In–OH bonds due to the hydroxylation process could induce more O V near the modified surface and the higher binding energy level was attributed to the coexistence of both of them. ,, In addition, the interstitial O 2– were also proven to appear in the same-energy region, such as 531.68 eV. At last, because of the limited detection depth of XPS (a few nanometers), relatively less O L were visible in Au/In 2 O 3 substrates, which also contributed to the decreased percentage of O L in the SAM-functionalized Au/In 2 O 3 NFs .…”

Nitrogenous Interlayers for ITO S/D Electrodes in N‐Type Organic Thin Film Transistors

“…To explore the inherent mechanism of the nitrogenous interlayer modification, we tried to construct a simplified model on the surface of ITO substrate. Based on our previous study about the optimized ITO (001) surface, [ 22 ] a hydroxyl group was introduced on the top of one In atom to simulate the normal ITO surface in the air, as shown in Figure a (the side view of ITO‐OH). Because of the high molecular weight for nitrogenous interlayers, an amine group and an ammonia molecule were used instead to simplify the [N] and [N + ] model, respectively.…”

Complementary Inverter Based on n‐Type and p‐Type OFETs with the Same Ambipolar Organic Semiconductor and ITO S/D Electrodes

“…[ 31–34 ] After the WF is adjusted to the range of 3.50–5.60 eV, ITO can well match most organic semiconductors (OSCs). [ 17–34 ]…”

“…When ITO is treated with halogen solvents, such as chlorobenzene, chloroform, and dichlorobenzene, polarized InCl bonds formed on the surface of ITO will also increase the WF of ITO. [22][23][24] In addition, there are many modification strategies used to reduce the ITO WF. Coated with thin metal-oxide films, such as In 2 O 3 , [25] ZnO, [26] In-doped ZnO, [27] or Al-doped ZnO, [28] ITO WF can be reduced, but not largely.…”

“…[31][32][33][34] After the WF is adjusted to the range of 3.50-5.60 eV, ITO can well match most organic semiconductors (OSCs). [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Second, we hope to find one kind of organic semiconductor, instead of necessary two kinds, to construct n-type and p-type OFETs simultaneously. Organic ambipolar materials are the preferred for their characteristics of exhibiting n-type performance in OFETs constructed with low WF S/D electrodes, [34] while exhibiting p-type performance in OFETs constructed with high WF S/D electrodes.…”