Influences of semiconductor morphology on the mechanical fatigue behavior of flexible organic electronics

Lee, Youngjoo; Lee, Yong Uk; Yeon, Han-Wool; Shin, Hyungcheol; Evans, Louise; Joo, Young‐Chang

doi:10.1063/1.4845995

Cited by 16 publications

(10 citation statements)

References 18 publications

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“…The high contact resistance is most likely to be related to the growth method, misorientation of the organic molecules, or poor contact between the electrodes and the photoactive layer. [56] Compared to the report of Pipan et al, [21] our devices show a photocurrent that is about 200 times lower in value. However, they reported a photogenerated current of 60 nA at 1 V, when illuminated with a white LED (P = 19.8 µW), for a TIPSpentacene inkjet-printed two-terminal photosensing device with interdigitated electrodes, which are known to enhance the photogenerated current.…”

Section: Application As Photosensing Devicescontrasting

confidence: 62%

Wettability‐Assisted Process to Shape Organic Crystalline Printed Films

Sequeira

Martins

Vilarinho

et al. 2022

Adv Materials Inter

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In particular, the ease of fabrication of the active parts of these devices following solution-processing routes, such as inkjet printing, can deliver polycrystalline smooth films, with precise control over the dispensed volume. [10] Critical aspects in developing a printable device include the quality of the materials, the solution formulation, viscosity control, surface wetting to avoid solution dispersion, or long-term stability. [11,12] Specifically, viscosity is not only important for the film quality but also determines the printing technique [13] and can be divided into two main types, low viscosity or high viscosity solutions. Typically, volatile solutions do not use binders, surfactants, or other chemical additives and offer higher-purity materials. [14] However, these can affect film morphology and topography, creating the well-known "coffee-ring" effect. [15] It also presents an increased spread area with limited control of defined structures and has difficulties in controlling crystal nucleation and molecular aggregation, leading to defects, uneven thickness, and inferior device performance. [16] In this case, large and aligned crystalline domains are highly important, as they offer low charge transport anisotropy and low density of grain boundaries leading to higher optical-to-electrical conversion. [17,18] Strategies using solution-processing techniques have enabled high crystallinity organic semiconductor films. [19] However, these approaches present little or even no control on both the shape and size of the active semiconductorThe controlled growth of organic crystalline materials in predefined locations still poses a challenge for functional device application such as phototransistors, photoconductors, or photovoltaic solar cells. This work evidences the use of optical lithography and a fluoroalkylsilane to selectively modify the surface energy and how to create a wettability micro-patterned structure. These are then combined with non-contact printing of the organic solution providing custom-shaped films. To deliver printed films with improved morphological quality, key process parameters for high-performance organic materials are optimized. Particular attention is given to the adjustment of the concentration and solvent mixture to tune the jetting properties, and consequently, slow down the evaporation rate. Continuous films are obtained for an optimized number of droplets and spacing between them. Micro-Raman spectroscopy imaging confirms the crystalline nature of the printed films and the lack of impurities. To validate the method, rubrene and triisopropylsilylethynyl (TIPS)-pentacene are tested using two-terminal optoelectronic devices. TIPS-pentacene rectangular printed micrometric photosensor presents linear behavior and no hysteresis, reaching 0.33 nA under 18.1 mW cm −2 . The structural and optoelectronic characterization is in line with other micro-patterned examples, opening doors for new industrial applications.

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Section: Application As Photosensing Devicescontrasting

confidence: 62%

Wettability‐Assisted Process to Shape Organic Crystalline Printed Films

Sequeira

Martins

Vilarinho

et al. 2022

Adv Materials Inter

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“…Bending Fatigue Test : Cyclic bending tester was employed to measure the in‐situ resistance change while imposing bending fatigue under fixed, uniform strain conditions . The cyclic bending tester used in this study is capable of performing high number of bending cycles up to 1 000 000 with excellent resistance resolution of ≈0.003 ohm.…”

Section: Methodsmentioning

confidence: 99%

Highly Reliable Ag Nanowire Flexible Transparent Electrode with Mechanically Welded Junctions

Hwang

Shin

Kim

et al. 2014

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Deformation behavior of the Ag nanowire flexible transparent electrode under bending strain is studied and results in a novel approach for highly reliable Ag nanowire network with mechanically welded junctions. Bending fatigue tests up to 500,000 cycles are used to evaluate the in situ resistance change while imposing fixed, uniform bending strain. In the initial stages of bending cycles, the thermally annealed Ag nanowire networks show a reduction in fractional resistance followed by a transient and steady-state increase at later stages of cycling. SEM analysis reveals that the initial reduction in resistance is caused by mechanical welding as a result of applied bending strain, and the increase in resistance at later stages of cycling is determined to be due to the failure at the thermally locked-in junctions. Based on the observations from this study, a new methodology for highly reliable Ag nanowire network is proposed: formation of Ag nanowire networks with no prior thermal annealing but localized junction formation through simple application of mechanical bending strain. The non-annealed, mechanically welded Ag nanowire network shows significantly enhanced cyclic reliability with essentially 0% increase in resistance due to effective formation of localized wire-to-wire contact.

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“…Mechanically flexible transistors play an important role in the realization ones. [15][16][17] For example, disordered poly(3-hexylthiophene) (P3HT) films sustain much higher strain, without developing macroscopic cracks, than crystalline ones consisting of highly ordered nanofibrils. High crystallinity weakens mechanical flexibility of P3HT films and induces cracks at much lower strain.…”

Section: Introductionmentioning

confidence: 99%

“…[18] In another example, organic field-effect transistors (OFETs) based on crystalline, molecular 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) show higher increase of the electrical resistance during deformation due to the formation of mechanical defects compared to amorphous poly(triarylamine) (PTAA). [15] Mechanical properties of conjugated polymer films, including their tensile strength, yield point and elongation at yield, also improve with higher molecular weight. [1,14] Therefore, a trade-off between good charge carrier transport and mechanical properties is necessary for the application of conjugated polymers in flexible OFET devices.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Fatigue Resistance of Polydiketopyrrolo‐Pyrrole‐Dithienylthieno[3,2‐b]thiophene‐Based Flexible Field‐Effect Transistors

Kubik

Waliszewski

Nosal

et al. 2022

Adv Materials Inter

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Mechanical durability is one of the main obstacles of flexible organic electronic devices. In this work, the fatigue behavior of flexible field‐effect transistors based on a diketopyrrolo‐pyrrole‐dithienylthieno[3,2‐b]thiophene polymer is reported. An especially for that purpose designed bending setup allows to perform precise multiple deformation cycles of the transistor channel area while monitoring the device behavior. The transistors show high operational stability upon 100 bending cycles at a radius of 500 µm. Bending at smaller radius of 100 µm leaves the functionality of the parylene dielectric intact but induces serious mechanical fractures in the semiconducting film. Despite macroscopic defects, the transistors still reveal good reliability including high charge carrier mobility, due to presence of sufficient pathways for the charge carrier transport and to a low gate leakage. It is also observed that thinner polymer films are more sensitive to the deformation‐induced defects leading to a larger decrease in device performance, especially during the initial bending cycles. In thicker DPP‐DTT films, the crack propagation less affects the semiconductor/dielectric interface, at which the main charge carrier transport take place, resulting in a more stable device operation. Therefore, the work provides fundamental understanding of the fatigue behavior of flexible transistors based on semiconducting polymers.

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Influences of semiconductor morphology on the mechanical fatigue behavior of flexible organic electronics

Cited by 16 publications

References 18 publications

Wettability‐Assisted Process to Shape Organic Crystalline Printed Films

Wettability‐Assisted Process to Shape Organic Crystalline Printed Films

Highly Reliable Ag Nanowire Flexible Transparent Electrode with Mechanically Welded Junctions

Mechanical Fatigue Resistance of Polydiketopyrrolo‐Pyrrole‐Dithienylthieno[3,2‐b]thiophene‐Based Flexible Field‐Effect Transistors

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