A skin‐like photodiode (PD) that is stretchable and skin‐conformable is crucial to opening the next‐generation wearable electronics for optical biometric monitoring, biomedical imaging, and others. To achieve reliable PD characteristics under large deformation, stretchable PDs with high detectivity and high mechanical stretchability must be developed. Herein, intrinsically stretchable polymer‐based PDs (is‐PPDs) comprising all‐polymeric constituent layers are demonstrated. In particular, elastomeric photoactive layers consisting of an elastomer with p‐/n‐type semiconducting polymers and conducting polymer‐based stretchable transparent electrodes with modulated work functions improve both the mechanical stability and the detectivity (D*) of is‐PPDs. Accordingly, is‐PPDs show excellent D* over 1013 Jones with a suppressed dark current density of 0.1 nA cm−2 before and after 100% stretching. The proposed is‐PPDs record high‐quality and stable photoplethysmography signals at the wrist with outward extension.

We have developed polymer-dispersed liquid crystal display (PDLCD) driven by ink-jet printed OFET. Novel pixel design and cell architecture are proposed to obtain enough current to drive PDLCD and high aperture ratio. 4.8 inch color reflective display has been fabricated successfully with the reflectivity of 18 % and contrast ratio of 4:1.

The interface between dielectric and organic semiconductor is critically important in determining organic thin‐film transistor (OTFT) performance. Surface polarity of the dielectric layer can hinder charge transport characteristics, which has restricted utilization of polymeric dielectric materials containing polar functional groups. Herein, the electrical characteristics of OTFTs are analyzed depending on the alkyl chain length of organic semiconductors and surface polarity of polymer dielectrics. High‐performance dibenzothiopheno[6,5‑b:6′,5′‑f]thieno[3,2‑b]thiophene (DBTTT) and newly synthesized its alkylated derivatives (C6‐DBTTT and C10‐DBTTT) are utilized as organic semiconductors. As dielectric layers, non‐polar poly(1,3,5‐trimethyl‐1,3,5‐trivinylcyclitrisiloxane) (pV3D3) and poly(2‐cyanoethyl acrylate‐co‐diethylene glycol divinyl ether) [p(CEA‐co‐DEGDVE)] with polar cyanide functionality are utilized. The fabricated OTFTs with pV3D3 commonly exhibit the excellent charge transport characteristics. In addition, the OTFT performance is improved with lengthening the alkyl chain in organic semiconductors, which can be attributed to the molecular orientation of semiconductors. On the other hand, non‐alkylated DBTTT OTFTs with polar p(CEA‐co‐DEGDVE) show relatively poor electrical characteristics, while their performance is drastically enhanced with the alkylated DBTTTs. The ultraviolet photoelectron spectroscopy (UPS) reveals that surface polarity of the dielectric layer can be abated with alkyl chain in organic semiconductors. It is believed that this study can provide a useful insight to optimize dielectric/semiconductor interface to achieve high‐performance OTFTs.

In order to improve device processability, it is important that organic semiconducting materials have good thermal durability. In article number https://doi.org/10.1002/aelm.201700142, Joon Hak Oh, Jeong‐Il Park, and co‐workers describe the synthesis and chargetransport behavior of a new thermally durable organic semiconductor, dibenzothiopheno[6,5‐b:6′,5′‐f]thieno[3,2‐b]thiophene (DPh‐DBTTT), using crystallographic analysis and an organic field‐effect transistor platform. Its outstanding electrical properties combined with thermal durability substantially extends the number of practical organic semiconductor applications.