Understanding mechanical behavior and reliability of organic electronic materials

Kim, Jae-Han; Lee, Inhwa; Kim, Taek‐Soo; Rolston, Nicholas; Watson, Brian L.; Dauskardt, Reinhold H.

doi:10.1557/mrs.2017.3

Cited by 46 publications

(43 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this progress report, we explore various approaches taken by different research groups to overcome the challenge for developing stretchable semiconducting polymers with an emphasis on polymer design. There are several excellent reviews and perspectives written recently on stretchable conductors and semiconductors . Those written on semiconductors mainly focused on either device architecture or stretchable materials specifically for TFT, PV, or LED devices .…”

Section: Introductionmentioning

confidence: 99%

Stretchable Polymer Semiconductors for Plastic Electronics

Wang

Gasperini

Bao

2018

Adv Elect Materials

191

198

View full text Add to dashboard Cite

More recently, there is a shift in research focus to exploiting the mechanical deformability of conjugated polymers due to the rapidly growing demand for wearable and implantable devices. [35][36][37][38][39] Since human bodies and organs are soft, curved, and constantly moving, flexible and stretchable devices are essential for comfort conformability, precise measurement, and longevity of bioelectronics such as medical implants, wearable biosensors, and prosthesis. [40,41] Currently, this has been achieved utilizing geometric approaches such as metallic serpentine or Kirigami interconnects [41][42][43] and induced buckling [44][45][46] to impart stretchability on rigid silicon-based devices. However, next-generation wearable and implantable electronics will benefit from intrinsic stretchability and unique biological properties such as self-healing and biodegradability for high-density and biocompatible devices. Conjugated polymers are attractive candidates to this end for several reasons: They have relatively low tensile modulus (≈1 GPa or lower)compared to that of silicon and inorganic semiconductors (≈100 GPa), which provides a softer interface suitable for bioelectronics. 2. Polymers possess great potential in incorporation of tough, elastic, and self-healing properties via molecular design, polymer chain entanglement, cross-links, and noncovalent interactions. Most biological tissues are also polymeric in nature. 3. With the advancements in organic chemistry, polymer chemical structures are highly tunable, hence biocompatible and biodegradable if desired. [47] 4. Polymers can be designed to be solution processable which allows them to be printed and patterned over large areas. [48][49][50][51][52] However, the major challenge faced in developing such polymers lies in maintaining good electrical and mechanical properties simultaneously. Due to the extended π-conjugation of the polymer backbone that is vital for good electronic properties, semiconducting polymers are often rigid and semicrystalline. For TFT application, semiconductor design usually aims to achieve highly crystalline morphology to obtain high charge carrier mobility.Conjugated polymers have evolved significantly in the past decade and have proven to be more than poorly conducting plastics. Instead, improved understanding has resulted in respectable charge-carrier mobilities and power-conversion efficiencies achieved by various donor-acceptor-type semiconducting polymers. However, their advantages in mechanical flexibility and deformability seem to have conflicting molecular design requirements from those for high charge-carrier transporting properties. It is therefore a challenge to enhance the mechanical compliance of semiconducting polymers suitable for stretchable device applications. This progress report starts with a brief introduction to fracture mechanics and mechanical characterization techniques for thin polymer films, in order to consider the limitations and rationalization of current definition and parameters for stretchability. It t...

show abstract

Section: Introductionmentioning

confidence: 99%

Stretchable Polymer Semiconductors for Plastic Electronics

Wang

Gasperini

Bao

2018

Adv Elect Materials

191

198

View full text Add to dashboard Cite

show abstract

“…Furthermore, most small molecules act as antiplasticizers, resulting in polymer:small molecule blend films being relatively brittle. This prevents the ability to strain orient the film to achieve significant polarization sensitivity . An alternative is to employ polymer semiconductors for both the electron donor and acceptor in the BHJ, where strain alignment would result in both polymers becoming sensitive to polarized light.…”

Section: Introductionmentioning

confidence: 99%

Panchromatic All‐Polymer Photodetector with Tunable Polarization Sensitivity

Sen

Yang

Rech

et al. 2018

Advanced Optical Materials

View full text Add to dashboard Cite

In this report, a high‐performance all‐polymer organic photodetector that is sensitive to linearly polarized light throughout the visible spectrum is demonstrated. The active layer is a bulk heterojunction composed of an electron donor polymer PBnDT‐FTAZ and acceptor polymer P(NDI2OD‐T2) that have complementary spectral absorption resulting in efficient detection from 350 to 800 nm. The blend film exhibits good ductility with the ability to accommodate large strains of over 60% without fracture. This allows the film to undergo large uniaxial strain resulting in in‐plane alignment of both polymers making the film optically anisotropic and intrinsically polarization sensitive. The films are characterized by UV–vis spectroscopy and grazing incidence wide‐angle X‐ray scattering showing that both polymers have similar in‐plane backbone alignment and maintain packing order after being strained. The films are integrated into devices and characterized under linear polarized light. The strain‐oriented detectors have maximum photocurrent anisotropies of 1.4 under transverse polarized light while maintaining peak responsivities of 0.21 A W−1 and a 3 dB cutoff frequency of ≈1 kHz. The demonstrated performance is comparable to the current state of the art all‐polymer photodetectors with the added capability of polarization sensitivity enabling new application opportunities.

show abstract

“…To test the intrinsic mechanical integrity of an ideal MAPbI 3 layer with an absence of defects or grain boundaries, we measured the cohesion energy of a single crystal of MAPbI 3 perovskite that was synthesized following literature methods. [26,27] Therefore, the poor mechanical and chemical reliability exhibited by MAPbI 3 solar cells are significant challenges that must be overcome to take full advantage of the often-cited, ultrasteep improvements in efficiency achieved by perovskites. [14] A number of reports have seemingly overcome this mechanical instability of perovskite solar cells and demonstrated flexible devices capable of withstanding hundreds of bending cycles; [23,24] however, simply bending a device does not prove that the materials comprising the device are mechanically stable.…”

mentioning

confidence: 99%

Effect of Cation Composition on the Mechanical Stability of Perovskite Solar Cells

Rolston

Printz

Tracy

et al. 2017

Advanced Energy Materials

Self Cite

155

181

View full text Add to dashboard Cite

Hybrid perovskites are recently developed photoactive semiconductors that hold great promise for next-generation solar cells, with devices incorporating them reaching certified efficiencies as high as 22.1%. [1] This high performance is coupled with a relative low cost, as perovskites comprise earth-abundant elements that are amenable to deposition from the solution-state by scalable, inexpensive printing processes. [2] Recent work has focused on improving their long-term stability with significant progress being reported in encapsulation techniques and scalability with the production of modulescale devices (100 cm 2 ) exhibiting efficiencies of over 11%. [3][4][5][6] These developments have resulted in efforts to commercialize perovskite solar cells; however, there is still concern over the potential to achieve the 25-year service lifetimes necessary to make perovskites a disruptive technology.Photoactive perovskite semiconductors are highly tunable, with numerous inorganic and organic cations readily incorporated to modify optoelectronic properties. However, despite the importance of device reliability and long service lifetimes, the effects of various cations on the mechanical properties of perovskites are largely overlooked. In this study, the cohesion energy of perovskites containing various cation combinations of methylammonium, formamidinium, cesium, butylammonium, and 5-aminovaleric acid is reported. A trade-off is observed between the mechanical integrity and the efficiency of perovskite devices. High efficiency devices exhibit decreased cohesion, which is attributed to reduced grain sizes with the inclusion of additional cations and PbI 2 additives. Microindentation hardness testing is performed to estimate the fracture toughness of single-crystal perovskite, and the results indicated perovskites are inherently fragile, even in the absence of grain boundaries and defects. The devices found to have the highest fracture energies are perovskites infiltrated into a porous TiO 2 /ZrO 2 /C triple layer, which provide extrinsic reinforcement and shielding for enhanced mechanical and chemical stability. Perovskite Solar CellsThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

show abstract

Understanding mechanical behavior and reliability of organic electronic materials

Abstract: Abstract

Cited by 46 publications

References 37 publications

Stretchable Polymer Semiconductors for Plastic Electronics

Stretchable Polymer Semiconductors for Plastic Electronics

Panchromatic All‐Polymer Photodetector with Tunable Polarization Sensitivity

Effect of Cation Composition on the Mechanical Stability of Perovskite Solar Cells

Contact Info

Product

Resources

About