Poly(3,4-ethyldioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), as an thermoelectric(TE) material, exhibits a high electrical conductivity and ZT value (10 À1 -10 0 ). Nevertheless, a low thermovoltage of the organic thermoelectric materials must be overcome, in comparison to that of semi metals. Recently, to address these challenges, several researchers have investigated PEDOT:PSS/carbon material composites.Herein, a transparent and flexible hybrid film made up of rapid thermal chemical vapor deposition (RTCVD) graphene and PEDOT:PSS results in enhanced TE performance. The PEDOT:PSS was synthesized by oxidative polymerization, and the hybrid process of the graphene film and PEDOT:PSS film was conducted using the layer-by-layer method. The results of AFM and Raman spectroscopy revealed that the synergistic effect through composite films improved the electrical properties. The maximum electrical conductivity and power factor of the RTCVD graphene/PEDOT:PSS (RCG/P) hybrid film were 1096 S cm À1 and 57.9 mW m À1 K À2, respectively. In addition, the RCG/P hybrid film exhibited excellent mechanical flexibility and stability.

Poly(3,:poly(4-styrene sulfonate) (PEDOT:PSS) has demonstrated outstanding performance as a charge transport layer or an electrode in various electronic devices, including organic solar cells, organic lightemitting diodes, and organic field-effect transistors (OFETs). The electrical properties of these devices are affected by the contact properties at the PEDOT:PSS−semiconductor junction. In this research, we performed work function (WF) engineering of electrohydrodynamic (EHD)-jet-printed PEDOT:PSS and successfully used it as an electrode to fabricate high-performance OFETs and complementary logic circuits. Two types of PEDOT:PSS materials−one with a high WF (HWF, 5.28 eV) and the other with a low WF (LWF, 4.53 eV)−were synthesized and EHD-jet-printed. The WF of PEDOT:PSS was deterministically modulated by approximately 0.75 eV through simple mixing of the two synthesized PEDOT:PSS materials in various ratios. OFETs fabricated with HWF and LWF PEDOT:PSS electrodes showed excellent electrical properties, including the ON/OFF switching ratio higher than 10 7 and the highest carrier mobility greater than 1 cm 2 •V −1 •s −1 . Furthermore, the HWF and LWF PEDOT:PSS electrodes were integrated to fabricate complementary metal−oxide− semiconductor (CMOS) NOT, NOR, and NAND circuits.

Stretchable materials are essential for next generation wearable and stretchable electronic devices. Intrinsically stretchable and highly conductive polymers (termed ISHCP) are designed with semi interpenetrating polymer networks (semi-IPN) that enable polymers to be simultaneously applied to transparent electrodes and electrochromic materials. Through a facile method of acid-catalyzed polymer condensation reaction, optimized ISHCP films show the highest electrical conductivity, 1406 S/cm, at a 20% stretched state. Without the blending of any other elastomeric matrix, ISHCP maintains its initial electrical properties under a cyclic stretch-release of over 50% strain. A fully stretchable electrochromic device based on ISHCP is fabricated and shows a performance of 47.7% ∆T and high coloration efficiency of 434.1 cm2/C at 590 nm. The device remains at 45.2% ∆T after 50% strain stretching. A simple patterned electrolyte layer on a stretchable electrochromic device is also realized. The fabricated device, consisting of all-plastic, can be applied by a solution process for large scale production. The ISHCP reveals its potential application in stretchable electrochromic devices and satisfies the requirements for next-generation stretchable electronics.

Even though poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been commonly used as a hole extraction layer (HEL) for p-i-n perovskite solar cells (PSCs), the cells' photovoltaic performance deteriorates because of the low and unstable work functions (WFs) of PEDOT:PSS versus those of a perovskite layer. To overcome this drawback, we synthesized a copolymer (P(SS- co-TFPMA)) ionomer consisting of PSS and tetrafluoropropylmethacrylate (TFPMA) as an alternative to conventional PEDOT:PSS. The PEDOT:P(SS- co-TFPMA) copolymer solution and its film exhibited excellent homogeneity and high phase stability compared with a physical mixture of TFPMA with PEDOT:PSS solution. During spin coating, a self-organized conducting PEDOT:P(SS- co-TFPMA) HEL evolved and the topmost PEDOT:P(SS- co-TFPMA) film showed a hydrophobic surface with a higher WF compared to that of the pristine PEDOT:PSS film because of its chemically bonded electron-withdrawing fluorinated functional groups. Interestingly, the WF of the conventional PEDOT:PSS film dramatically deteriorated after being coated with a perovskite layer, whereas the PEDOT:P(SS- co-TFPMA) film represented a relatively small influence. Because of the superior energy-level alignment between the HEL and a perovskite layer even after the contact, the open-circuit voltage, short-circuit current, and fill factor of the inverted planar p-i-n PSCs (IP-PSCs) with PEDOT:P(SS- co-TFPMA) were improved from 0.92 to 0.98 V, 18.96 to 19.66 mA/cm, and 78.96 to 82.43%, respectively, resulting in a 15% improvement in the power conversion efficiency vs that of IP-PSCs with conventional PEDOT:PSS. Moreover, the IP-PSCs with PEDOT:P(SS- co-TFPMA) layer showed not only improved photovoltaic performance but also enhanced device stability due to hydrophobic surface of PEDOT:P(SS- co-TFPMA) film.

Electrochromic devices (ECDs) exhibit significant potential as emerging electronics for applications associated with smart windows. They can dynamically control solar radiation consumption in buildings and vehicles to enhance efficiency. However, because smart windows are not optimized for high performance, and most are manufactured based on glass form, the large-area manufacturing process is complex and hinders its applicability to electrochromic (EC) devices. In this study, an ECD was fabricated on a PET film by a solution process using a multifunctional conducting polymer synthesized by oxidation polymerization. The polymer layer used was PEDOT:PSS and PANI:PSS, which alone can serve as an electrode and an EC layer, without the need for other electrode materials (ITO, FTO, etc.). The ECD showed excellent optical characteristics and cycle stability owing to the balanced surface charge capacity (insertion/exertion). An excellent coloration efficiency value (1872.8 cm2 C–1 at 600 nm) was obtained with low-power consumption (102 μW cm–2 (coloration) and 11 μW cm–2 (bleaching)). The characteristics of these materials and devices have significant applicability as large-area smart windows. When fabricated using the roll-to-roll method, a large-area smart window of 500 × 500 mm2 was produced. The heat-shielding characteristics (86.2%) were also excellent. Very good energy-savings were achieved and an all-organic smart window with excellent characteristics was verified. The capability of solution and low temperature processing for ECDs has the ability to significantly influence the industrialization of large-area smart windows.