A stretchable and self‐healable conductive material with high conductivity is critical to high‐performance wearable electronics and integrated devices for applications where large mechanical deformation is involved. While there has been great progress in developing stretchable and self‐healable conducting materials, it remains challenging to concurrently maintain and recover such functionalities before and after healing. Here, a highly stretchable and autonomic self‐healable conducting film consisting of a conducting polymer (poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS) and a soft‐polymer (poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid), PAAMPSA) is reported. The optimal film exhibits outstanding stretchability as high as 630% and high electrical conductivity of 320 S cm−1, while possessing the ability to repair both mechanical and electrical breakdowns when undergoing severe damage at ambient conditions. This polymer composite film is further utilized in a tactile sensor, which exhibits good pressure sensitivity of 164.5 kPa−1, near hysteresis‐free, an ultrafast response time of 19 ms, and excellent endurance over 1500 consecutive presses. Additionally, an integrated 5 × 4 stretchable and self‐healable organic electrochemical transistor (OECT) array with great device performance is successfully demonstrated. The developed stretchable and autonomic self‐healable conducting film significantly increases the practicality and shelf life of wearable electronics, which in turn, reduces maintenance costs and build‐up of electronic waste.

The ability to operate in aqueous environments makes poly(3,4-ethylenedioxyt hiophene):poly(styrenesulfonate), PEDOT:PSS, based organic electrochemical transistors (OECTs) excellent candidates for a variety of biological applications. Current research in PEDOT:PSS based OECTs is primarily focused on improving the conductivity of PEDOT:PSS film to achieve high transconductance (g m ). The improved conductivity and electronic transport are attributed to the formation of enlarged PEDOT-rich domains and shorter PEDOT stacking, but such a change in morphology sacrifices the ionic transport and, therefore, the doping/de-doping process. Additionally, little is known about the effect of such morphology changes on the gate bias that makes the maximum g m ( P Pe ea ak k V G G ), threshold voltage (V T ), and transient behavior of PEDOT:PSS based OECTs. Here, the molecular packing and nanostructure of PEDOT:PSS films are tuned using ionic liquids as additives, namely, 1-Ethyl-3-methylimidazolium (EMIM) as cation and anions of chloride (Cl), trifluoromethanesulfonate (OTF), bis(trifluoromethylsulfonyl)imide (TFSI), and tricyanomethanide (TCM). It is demonstrated that an optimal morphology is realized using EMIM OTF ionic liquids that generate smaller fibril-like PEDOT-rich domains with relatively loose structures. Such optimal morphology improves ion accessibility, lowering the gate bias required to completely de-dope the channel, and thus enabling to achieve high transconductance, fast transient response, and at lower gate bias window simultaneously.

This mini-review gives a simple overview of the workings of organic photovoltaic (OPV) devices, the way in which charge transfer occurs through the active layers, and then introduces how photo-induced charge carrier extraction by linearly increasing voltage (photo-CELIV) and time of flight (TOF) techniques can be employed to give comprehensive indications of charge carrier mobility, density and recombination in OPVs. It is shown how photo-CELIV and TOF characterizations, using extraction current transients, can give an understanding of degradation mechanisms through observation of the trapping of charge carriers and bimolecular recombination. Examples of deployment and the interpretation of the results are given. It is hoped that this brief introduction will serve as a stepping stone into more in-depth papers and books and encourage wider use of photo-CELIV and TOF technologies which can be employed with whole devices.