π‐σ‐Phosphonic Acid Organic Monolayer/Sol–Gel Hafnium Oxide Hybrid Dielectrics for Low‐Voltage Organic Transistors

Acton, Orb; Ting, Guy; Ma, Hong; Ka, Jae Won; Yip, Hin‐Lap; Tucker, Neil M.; Jen, Alex K.‐Y.

doi:10.1002/adma.200800810

Cited by 148 publications

(149 citation statements)

References 45 publications

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“…Some of the SAMs would require relatively long preparation time [12][13][14] and usually the functional head groups of SAMs is dielectric specifi c. It is challenging to develop a universal SAMs suitable for different dielectric insulators. More importantly, the SAM also modifi es the surface energy of the dielectric and affects the crystallinity of the organic semiconductors.…”

mentioning

confidence: 99%

Low Cost Universal High‐k Dielectric for Solution Processing and Thermal Evaporation Organic Transistors

Wang

Ren

Fan

et al. 2014

Adv Materials Inter

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SAM is needed to reduce the leakage current through the gate and dielectric. Some of the SAMs would require relatively long preparation time [12][13][14] and usually the functional head groups of SAMs is dielectric specifi c. It is challenging to develop a universal SAMs suitable for different dielectric insulators. More importantly, the SAM also modifi es the surface energy of the dielectric and affects the crystallinity of the organic semiconductors. It is necessary to employ a suitable SAM to achieve high crystallility and carrier mobility in the OFETs. [ 14 ] To date, it is still a great challenge in the research fi eld to develop a universal high-k material which does not require SAM, and can be processed at moderate temperature, ambient air environment, and adjustable surface energy for both thermal evaporation and solution processing of organic semiconductors.To address these challenges, we recently reported a high-k (ε r = 11) barium strontium titanate (BST) thin fi lm treated by UV-Ozone and deposited by multi-layer spin coating deposition. [ 15 ] The high-k fi lms are spin coated in ambient air and heated to a temperature of around 85 °C during the UV-Ozone process. The UV emits at 184.9 nm and 253.7 nm under ambient air conditions converting oxygen into reactive O species, which then diffuse into the amorphous BST thin fi lm and reacts with the oxygen vacancies to form lattice oxygen. The reactive oxygen also removes the organic impurities in the fi lm, which results in a high quality amorphous BST thin fi lm with better stoichiometry. [ 16 ] The compatibility with ambient air environment, low processing temperature, and no SAM requirement suggest the BST dielectric has extremely high potentials to be applied in developing low cost OFETs on plastic fl exible substrates and have advantages over other polymers and inorganic materials. In the current study, we investigate the surface energy modifi cation effect by varying the storage environment and time of the BST thin fi lm in order to achieve a universal high-k material for OFET fabrications without using SAM. Based on the contact angle measurements, we calculated the surface energy and the wetting envelope of the BST high-k dielectric stored under different fi ve different conditions. The fresh BST with hydrophilic surface is suitable for spin coating or drop casting of organic semiconductor deposition where surface wetting is needed for the alignment of organic molecules. On the other hand, the BST thin fi lms stored under different conditions show different surface energy, which will directly affect the crystallinity of the organic semiconductors. On the current BST high-k dielectric without SAM and further optimization, dinaphtho[2,3-b:2′,3′-f ] thieno[3,2-b] thiophene (DNTT) and 6,13-Bis (triisopropylsilylethynyl) pentacene (TIPS-pentacene) organic transistors with average mobility of 1.51 cm 2 V −1 s −1 and 0.11 cm 2 V −1 s −1 are formed by thermal evaporation and droplet-pinned crystallization (DPC) method (one of the solution processing methods...

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mentioning

confidence: 99%

Low Cost Universal High‐k Dielectric for Solution Processing and Thermal Evaporation Organic Transistors

Wang

Ren

Fan

et al. 2014

Adv Materials Inter

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“…Similar study found poor insulating properties of n-hexylphosphonic acid (C 6 PA) SAM and low transistor field-effect mobility for ndecylphosphonic acid (C 10 PA) SAM [20]. Longer chain C 18 PA and anthryl-alkyl-phosphonic acid SAMs were used to improve the insulating properties of the oxide layers [23,27].…”

Section: -9mentioning

confidence: 88%

“…To date the self-assembled monolayers based on alkyl phosphonic acids [20][21][22][23][24][25][26][27] have been obtained by solution process only. In this paper we present that such monolayers can be prepared by dry method as well.…”

Section: -9mentioning

confidence: 99%

Dry growth of n-octylphosphonic acid monolayer for low-voltage organic thin-film transistors

Gupta¹,

Glesková²

2013

Organic Electronics

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“…Ceramic-based inorganic materials with a high dielectric constant (high-k) can be used as a way to lower the operating voltage of organic TFTs [7][8][9]. However, most high-k materials that are suitable for organic TFTs are processed via deposition techniques and sol-gel methods and require high processing temperatures that are not suitable for plastic substrate application.…”

Section: Introductionmentioning

confidence: 99%

Stability Study of Flexible 6,13-Bis(triisopropylsilylethynyl)pentacene Thin-Film Transistors with a Cross-Linked Poly(4-vinylphenol)/Yttrium Oxide Nanocomposite Gate Insulator

et al. 2016

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Abstract:We investigated the electrical and mechanical stability of flexible 6,13-bis (triisopropylsilylehtynyl)pentacene (TIPS-pentacene) thin-film transistors (TFTs) that were fabricated on polyimide (PI) substrates using cross-linked poly(4-vinylphenol) (c-PVP) and c-PVP/yttrium oxide (Y 2 O 3 ) nanocomposite films as gate insulators. Compared with the electrical characteristics of TIPS-pentacene TFTs with c-PVP insulators, the TFTs with c-PVP/Y 2 O 3 nanocomposite insulators exhibited enhancements in the drain current and the threshold voltage due to an increase in the dielectric capacitance. In electrical stability experiments, a gradual decrease in the drain current and a negative shift in the threshold voltage occurred during prolonged bias stress tests, but these characteristic variations were comparable for both types of TFT. On the other hand, the results of mechanical bending tests showed that the characteristic degradation of the TIPS-pentacene TFTs with c-PVP/Y 2 O 3 nanocomposite insulators was more critical than that of the TFTs with c-PVP insulators. In this study, the detrimental effect of the nanocomposite insulator on the mechanical stability of flexible TIPS-pentacene TFTs was found to be caused by physical adhesion of TIPS-pentacene molecules onto the rough surfaces of the c-PVP/Y 2 O 3 nanocomposite insulator. These results indicate that the dielectric and morphological properties of polymeric nanocomposite insulators are significant when considering practical applications of flexible electronics operated at low voltages.

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π‐σ‐Phosphonic Acid Organic Monolayer/Sol–Gel Hafnium Oxide Hybrid Dielectrics for Low‐Voltage Organic Transistors

Cited by 148 publications

References 45 publications

Low Cost Universal High‐k Dielectric for Solution Processing and Thermal Evaporation Organic Transistors

Low Cost Universal High‐k Dielectric for Solution Processing and Thermal Evaporation Organic Transistors

Dry growth of n-octylphosphonic acid monolayer for low-voltage organic thin-film transistors

Stability Study of Flexible 6,13-Bis(triisopropylsilylethynyl)pentacene Thin-Film Transistors with a Cross-Linked Poly(4-vinylphenol)/Yttrium Oxide Nanocomposite Gate Insulator

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