Progress in understanding structure and transport properties of PEDOT-based materials: A critical review

https://onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.201904102

Monolithic Perovskite Tandem Solar Cells: A Review of the Present Status and Advanced Characterization Methods Toward 30% Efficiency

Stretchable electronics, which can retain their functions under stretching, have attracted great interest in recent decades. Elastic substrates, which bear the applied strain and regulate the strain distribution in circuits, are indispensable components in stretchable electronics. Moreover, the self-healing property of the substrate is a premise to endow stretchable electronics with the same characteristics, so the device may recover from failure resulting from large and frequent deformations. Therefore, the properties of the elastic substrate are crucial to the overall performance of stretchable devices. Poly(dimethylsiloxane) (PDMS) is widely used as the substrate material for stretchable electronics, not only because of its advantages, which include stable chemical properties, good thermal stability, transparency, and biological compatibility, but also because of its capability of attaining designer functionalities via surface modification and bulk property tailoring. Herein, the strategies for fabricating stretchable electronics on PDMS substrates are summarized, and the influence of the physical and chemical properties of PDMS, including surface chemical status, physical modulus, geometric structures, and self-healing properties, on the performance of stretchable electronics is discussed. Finally, the challenges and future opportunities of stretchable electronics based on PDMS substrates are considered.

Stretchable Electronics Based on PDMS Substrates.

A critical review on semitransparent organic solar cells

In recent years, highly sensitive pressure sensors that are flexible, biocompatible, and stretchable have attracted significant research attention in the fields of wearable electronics and smart skin. However, there has been a considerable challenge to simultaneously achieve highly sensitive, low-cost sensors coupled with optimum mechanical stability and an ultralow detection limit for subtle physiological signal monitoring devices. Targeting aforementioned issues, herein, we report the facile fabrication of a highly sensitive and reliable capacitive pressure sensor for ultralow-pressure measurement by sandwiching MXene (Ti3C2Tx)/poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) composite nanofibrous scaffolds as a dielectric layer between biocompatible poly-(3,4-ethylenedioxythiophene) polystyrene sulfonate /polydimethylsiloxane electrodes. The fabricated sensor exhibits a high sensitivity of 0.51 kPa-1 and a minimum detection limit of 1.5 Pa. In addition, it also enables linear sensing over a broad pressure range (0-400 kPa) and high reliability over 10,000 cycles even at extremely high pressure (>167 kPa). The sensitivity of the nanofiber-based sensor is enhanced by MXene loading, thereby increasing the dielectric constant up to 40 and reducing the compression modulus to 58% compared with pristine PVDF-TrFE nanofiber scaffolds. The proposed sensor can be used to determine the health condition of patients by monitoring physiological signals (pulse rate, respiration, muscle movements, and eye twitching) and also represents a good candidate for a next generation human-machine interfacing device.

Wearable Capacitive Pressure Sensor Based on MXene Composite Nanofibrous Scaffolds for Reliable Human Physiological Signal Acquisition.

Substantial effort has been devoted to both scientific and technological developments of wearable, flexible, semitransparent, and sensing electronics (e.g., organic/perovskite photovoltaics, organic thin-film transistors, and medical sensors) in the past decade. The key to realizing those functionalities is essentially the fabrication of conductive electrodes with desirable mechanical properties. Conductive polymers (CPs) of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have emerged to be the most promising flexible electrode materials over rigid metallic oxides and play a critical role in these unprecedented devices as transparent electrodes, hole transport layers, interconnectors, electroactive layers, or motion-sensing conductors. Here, the current status of research on PEDOT:PSS is summarized including various approaches to boosting the electrical conductivity and mechanical compliance and stability, directly linked to the underlying mechanism of the performance enhancements. Along with the basic principles, the most cutting edge-progresses in devices with PEDOT:PSS are highlighted. Meanwhile, the advantages and plausible problems of the CPs and as-fabricated devices are pointed out. Finally, new perspectives are given for CP modifications and device fabrications. This work stresses the importance of developing CP films and reveals their critical role in the evolution of these next-generation devices featuring wearable, deformable, printable, ultrathin, and see-through characteristics.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/advs.201900813

PEDOT:PSS for Flexible and Stretchable Electronics: Modifications, Strategies, and Applications

An all annealing-free solution-manufacturing is regarded as a technological advancement for the development of flexible organic solar cells (OSCs), which can prevent the distortion of plastic substrates, avoid destroying the active components of the devices, and simplify the device fabrication. Here, we report an efficient all annealing-free solution-processed flexible OSC integrated on a soft polyethylene (PE) substrate. The transparent anodes, hole-transport layers, active layers and electron-transport layers are solution-processed at room temperature without thermal annealing treatments. Thanks to both the as-developed gentle superacid doping and air-drying treatments at room temperature that enable a high-merit flexible anode on the soft PE substrates, the annealing-free flexible OSCs yield a high efficiency of 14.66% along with a high power-per-weight of 6.33 W g−1, which is close to that (15.73%) of thermally annealed rigid OSCs based on indium tin oxide anodes. Due to the mild annealing-free solution-processing and the soft PE substrates having an extremely low Young's modulus of only 0.2 GPa, the flexible OSCs maintain a high flexibility in a harsh bending test.

All annealing-free solution-processed highly flexible organic solar cells

Vacuum‐Free, All‐Solution, and All‐Air Processed Organic Photovoltaics with over 11% Efficiency and Promoted Stability Using Layer‐by‐Layer Codoped Polymeric Electrodes

Rongjiang Wen

Papers

PEDOT:PSS for Flexible and Stretchable Electronics: Modifications, Strategies, and Applications

All annealing-free solution-processed highly flexible organic solar cells

Vacuum‐Free, All‐Solution, and All‐Air Processed Organic Photovoltaics with over 11% Efficiency and Promoted Stability Using Layer‐by‐Layer Codoped Polymeric Electrodes

Molecular dynamics simulation study of the transport of pairwise coupled ions confined in C-S-H gel nanopores

High-Efficiency Stable Flexible Organic Solar Cells with PEDOT:PSS Electrodes via Superacid Fumigation Treatment