Yijie Xia

Bio: Yijie Xia is an academic researcher from National University of Singapore. The author has contributed to research in topics: PEDOT:PSS & Conductive polymer. The author has an hindex of 21, co-authored 31 publications receiving 3615 citations. Previous affiliations of Yijie Xia include Fudan University & University of Shanghai for Science and Technology.

Solution‐Processed Metallic Conducting Polymer Films as Transparent Electrode of Optoelectronic Devices

Abstract: The conductivity of PEDOT:PSS films was significantly enhanced from 0.3 S cm(-1) to 3065 S cm(-1) through a treatment with dilute sulfuric acids. PEDOT:PSS films with a sheet resistance of 39 Ω sq(-1) and transparency of around 80% at 550 nm are obtained. These PEDOT:PSS films with conductivity and transparency comparable to ITO can replace ITO as the transparent electrode of optoelectronic devices.

Review on application of PEDOTs and PEDOT:PSS in energy conversion and storage devices

Abstract: Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is the most successful conducting polymer in terms of practical application. It possesses many unique properties, such as good film forming ability by versatile fabrication techniques, superior optical transparency in visible light range, high electrical conductivity, intrinsically high work function and good physical and chemical stability in air. PEDOT:PSS has wide applications in energy conversion and storage devices. This review summarizes its applications in organic solar cells, dye-sensitized solar cells, supercapacitors, fuel cells, thermoelectric devices and stretchable devices. Approaches to enhance the material/device performances are highlighted.

PEDOT:PSS films with significantly enhanced conductivities induced by preferential solvation with cosolvents and their application in polymer photovoltaic cells

Abstract: The conductivity of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films was significantly enhanced by preferential solvations of the hydrophobic PEDOT and hydrophilic PSS chains with cosolvents. When a PEDOT:PSS film prepared from the PEDOT:PSS aqueous solution was treated with water or a common organic solvent like ethanol, iso-propyl alcohol (IPA), acetonitrile (ACN), acetone, or tetrahydrofuran (THF), its conductivity did not change remarkably. But the conductivity was significantly enhanced when the PEDOT:PSS film was treated with a cosolvent of water and one of these common organic solvents. The conductivity enhancement was affected by several factors, including the ratio of the organic solvent to water, the dielectric constant of the organic solvent, and the temperature during the treatment. The conductivity enhancement from 0.2 S cm−1 to 103 S cm−1 was observed. The significant conductivity enhancement is attributed to the preferential solvation of PEDOT:PSS with a cosolvent. Water and the organic solvent of the cosolvent preferentially solvate the hydrophilic PSS and hydrophobic PEDOT chains, respectively. The preferential solvation of a PEDOT:PSS film with a cosolvent induces the phase separation of the insulator PSSH chains from the PEDOT:PSS film, aggregation of PSSH segments in the PEDOT:PSS film, and the conformational change of the PEDOT chains from coiled to linear. The cosolvent-treated PEDOT:PSS films were quite smooth and could be used to replace indium tin oxide (ITO) as the transparent electrode of electronic devices. Polymer photovoltaic cells (PVs) with the cosolvent-treated PEDOT:PSS films as the transparent electrode exhibited high photovoltaic performance.

Significant conductivity enhancement of conductive poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) films through a treatment with organic carboxylic acids and inorganic acids.

Abstract: Significant conductivity enhancement was observed on transparent and conductive poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films after a treatment with organic and inorga...

Highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) films treated with an amphiphilic fluoro compound as the transparent electrode of polymer solar cells

Abstract: Flexible transparent electrode materials are strongly needed for optoelectronic devices. We report a novel method to significantly enhance the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films through treatment with a fluoro compound, hexafluoroacetone (HFA). HFA hydrolyzes with water into a geminal diol, 1,1,1,3,3,3-hexafluoropropane-2,2-diol (HFP2OH) that has two –OH groups connected to the middle carbon atom. The conductivity increased from 0.3 to 1164 and 1325 S cm−1 after the treatment with HFA once and four times, respectively. The highly conductive HFA-treated PEDOT:PSS films can have a sheet resistances of 46 Ω □−1 and a transparency of around 83% at 550 nm. These values are comparable to those of indium tin oxide (ITO) on polyethylene terephthalate (PET). The conductivity enhancement is attributed to the HFP2OH-induced phase segregation of some hydrophilic PSSH chains from PEDOT:PSS and the conformational change of the conductive PEDOT chains, driven by the interactions between amphiphilic HFP2OH and PEDOT:PSS. The hydrophobic –CF3groups of HFP2OH preferentially interact with the hydrophobic PEDOT chains of PEDOT:PSS, while the hydrophilic –OH groups preferentially interact with hydrophilic PSS chains. The highly conductive PEDOT:PSS films were used to replace ITO as the transparent anode of polymer solar cells. Polymer solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) exhibited a photovoltaic efficiency of 3.57% under simulated AM1.5G illumination, comparable to the control devices with ITO as the anode.

Engineered doping of organic semiconductors for enhanced thermoelectric efficiency

Abstract: The conversion efficiency of heat to electricity in thermoelectric materials depends on both their thermopower and electrical conductivity. It is now reported that, unlike their inorganic counterparts, organic thermoelectric materials show an improvement in both these parameters when the volume of dopant elements is minimized; furthermore, a high conversion efficiency is achieved in PEDOT:PSS blends.

Solution‐Processed Metallic Conducting Polymer Films as Transparent Electrode of Optoelectronic Devices

Abstract: The conductivity of PEDOT:PSS films was significantly enhanced from 0.3 S cm(-1) to 3065 S cm(-1) through a treatment with dilute sulfuric acids. PEDOT:PSS films with a sheet resistance of 39 Ω sq(-1) and transparency of around 80% at 550 nm are obtained. These PEDOT:PSS films with conductivity and transparency comparable to ITO can replace ITO as the transparent electrode of optoelectronic devices.

Highly stretchable, transparent, and conductive polymer

Abstract: A polymer composition includes a conductive polymer and at least one stretchability and electrical conductivity (STEC) enhancer, wherein a content of the STEC enhancer in the composition is at least about 1 wt.% of the composition.

Highly conductive PEDOT:PSS nanofibrils induced by solution-processed crystallization.

Abstract: The fabrication of electronic devices based on organic materials, known as ’printed electronics’, is an emerging technology due to its unprecedented advantages involving fl exibility, light weight, and portability, which will ultimately lead to future ubiquitous applications. [ 1 ] The solution processability of semiconducting and metallic polymers enables the cost-effective fabrication of optoelectronic devices via high-throughput printing techniques. [ 2 ] These techniques require high-performance fl exible and transparent electrodes (FTEs) fabricated on plastic substrates, but currently, they depend on indium tin oxide (ITO) coated on plastic substrates. However, its intrinsic mechanical brittleness and inferior physical properties arising from lowtemperature ( T ) processing below the melting T of the plastic substrates (i.e., typically below 150 °C) have increased the demand for alternative FTE materials. [ 3 ]