A thienylene−vinylene−thienylene (TVT) derivative with cyano groups in the 3-and 3′-positions was synthesized as a building block of semiconducting polymers for high mobility organic field effect transistors (OFETs). (E)-1,2-Di-(3-cyanothiophen-2-yl)ethene (2CNTVT) was copolymerized with diketopyrrolopyrrole (DPP) units via Stille coupling reaction to give 2DPP-2CNTVT and 7DPP-2CNTVT. The properties of these two polymers were compared with those of the corresponding polymers without cyano groups in TVT (2DPP-TVT and 7DPP-TVT). The effects of CN groups and branched alkyl position were found to have a significant influence on the optical, electrochemical, morphological, and charge transporting properties of the polymers. The average hole mobilities of OFETs fabricated with 2DPP-TVT and 7DPP-TVT OFETs were 1.63 and 2.2 cm 2 V −1 s −1 , respectively, and the average electron mobility for both 2DPP-2CNTVT and 7DPP-2CNTVT OFETs was 1.2 cm 2 V −1 s −1 .

An organic conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS), is an attractive candidate for a low-cost, low-temperature, and solution-processed electrode material for achieving high-performance flexible and stretchable thin-film devices. Unlike most organic materials, this water-soluble conjugated polymer is highly stable against chemical and physical exposure. It exhibits the most superior mechanical flexibility and the highest optical transparency and electrical conductivity among all organic conductors. Therefore, this conductive polymer is among the most promising alternatives to the expensive, rigid, and brittle metal oxide-and even metal-based electrode materials, such as indium tin oxide (ITO) and gold, in the future solutionprocessed electronic devices. Nevertheless, the intrinsic conductivity of PEDOT:PSS is typically below 1 S cm −1 , which is too low for such devices. Fortunately, the material properties of PEDOT:PSS, including its conductivity, are easily tuned by employing a large number of simple approaches. In this paper, the reports on the successful application of PEDOT:PSS to a wide range of solution-processed organic devices, such as organic light-emitting diodes (OLEDs), organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs), are reviewed. The recent progress in the development of highly conductive PEDOT:PSS-based films for electrode applications in the field of organic electronics is the main focus of the discussion herein.

Transparent organic light‐emitting diodes (TOLEDs) are exciting next‐generation electronic devices that can be embedded and integrated into walls, windows, head‐up panels in commercial and domestic buildings, cars, planes, and other segments of the consumer goods sector. TOLEDs are also fundamental components for the realization of the stacked OLEDs for various industrial and research applications. Furthermore, futuristic smart wearables for clothing as well as medical purposes will also benefit remarkably from the development of TOLEDs. However, the efficiency of TOLEDs is significantly lower than that of their opaque counterparts. The achievement of high‐performance TOLEDs is directly dependent on the properties of the chosen electrode materials as well as the used light extraction techniques. In this review, the reported perspectives of TOLEDs are discussed along with their types, design, and architectures, applied TOLED materials and properties, and the application fields of these transparent devices. The performance of the electrode materials and the commonly used light extraction methods are reviewed in detail as well. The main purpose is to shed light on some of the effective TOLED approaches and the underlying reasons for the frequently encountered issues in these diodes. Auspicious novel fabrication techniques as well as device structures are also highlighted.

The general form of interfacial contact resistance was derived for organic thin-film transistors (OTFTs) covering various injection mechanisms. Devices with a broad range of materials for contacts, semiconductors, and dielectrics were investigated and the charge injections in staggered OTFTs was found to universally follow the proposed form in the diffusion-limited case, which is signified by the mobility-dependent injection at the metal-semiconductor interfaces. Hence, real ohmic contact can hardly ever be achieved in OTFTs with low carrier concentrations and mobility, and the injection mechanisms include thermionic emission, diffusion, and surface recombination. The non-ohmic injection in OTFTs is manifested by the generally observed hook shape of the output conductance as a function of the drain field. The combined theoretical and experimental results show that interfacial contact resistance generally decreases with carrier mobility, and the injection current is probably determined by the surface recombination rate, which can be promoted by bulk-doping, contact modifications with charge injection layers and dopant layers, and dielectric engineering with high-k dielectric materials.

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