Circular economy design considerations for research and process development in the chemical sciences

Recent advances in the synthesis of conducting polymers from the vapour phase

For the last two decades, polymer solar cells (PSCs) have been a cynosure of the photovoltaic community, as evidenced by the growing number of patent applications and scientific publications. Efforts to achieve high power conversion efficiency in PSC, propelled by advances in device architecture, material combination, and nanomorphology control, evolved into poly(3-hexylthiophene-2,5-diyl) (P3HT):phenyl-C61-Butyric-Acid-Methyl Ester (PCBM) bulk heterojunction PSCs, which had been the best seller in PSC research for a decade. Subsequently, PSC research was redirected towards the synthesis of low bandgap materials and optimization of tandem cells, which led to a power conversion efficiency of ∼13%. Even though this efficiency may not be sufficient enough to compete with that of inorganic solar cells, unique properties of PSCs, such as mass roll-to-roll production capability, as well as flexibility and lightness, suggest their niche market opportunities. In this review, an overview of developments in PSCs is...

Polymer solar cells: P3HT:PCBM and beyond

Graphene has been employed as transparent electrodes in organic solar cells (OSCs) because of its good physical and optical properties. However, the electrical conductivity of graphene films synthesized by chemical vapor deposition (CVD) is still inferior to that of conventional indium tin oxide (ITO) electrodes of comparable transparency, resulting in a lower performance of OSCs. Here, we report an effective method to improve the performance and long-term stability of graphene-based OSCs using electrostatically doped graphene films via a ferroelectric polymer. The sheet resistance of electrostatically doped few layer graphene films was reduced to ∼70 Ω/sq at 87% optical transmittance. Such graphene-based OSCs exhibit an efficiency of 2.07% with a superior stability when compared to chemically doped graphene-based OSCs. Furthermore, OSCs constructed on ultrathin ferroelectric film as a substrate of only a few micrometers show extremely good mechanical flexibility and durability and can be rolled up into a cylinder with 7 mm diameter.

Ultrathin organic solar cells with graphene doped by ferroelectric polarization.

Ultrahigh capacity anode material for lithium ion battery based on rod gold nanoparticles decorated reduced graphene oxide

We report the use of graphene as a highly transparent conductive film in liquid-crystal displays (LCDs). Graphene films were synthesised via chemical vapour deposition, transferred onto glass substrates, and then used to fabricate typical twisted nematic LCD cells. LCD cells using graphene as transparent electrodes exhibited optical transmittances 7.7% higher than LCD cells fabricated using conventional conducting layers based on indium tin oxide (ITO) films. The device characteristics of LCD cells based on graphene electrodes, such as threshold voltage and voltage holding ratio, were comparable to those of conventional LCD cells based on ITO electrodes. These results indicate that graphene is a promising transparent conductive film compared to ITO, yielding LCDs with significantly improved optical transmittance.

High-transmittance liquid-crystal displays using graphene conducting layers

The authors report the characteristics of organic solar cells (OSCs) fabricated on HNO3-treated multilayer graphene (MLG) transparent electrodes. MLG transparent electrodes were prepared using chemical vapor deposition and a multitransfer process. Compared to untreated-MLG electrodes with a fairly high sheet resistance (274 ± 1 Ω/sq) even though three layers of graphene were stacked together, HNO3-treated MLG electrode shows a lower sheet resistance of 119 ± 1 Ω/sq. OSCs (MLG/poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate)/Poly(3-hexylthiophere)/1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61/Ca/Al) fabricated on untreated-MLG transparent electrodes had an open-circuit voltage of 0.575 V, a short-circuit current of 8.08 mA/cm2, a fill factor of 43.5%, and a power conversion efficiency (PCE) of 2.02%. In contrast, application of HNO3-treated MLG films as transparent electrodes for OSCs led to improved performance with an open-circuit voltage of 0.602 V, a short-circuit current of 8.26 mA/cm2, a fil...

Organic photovoltaic devices with low resistance multilayer graphene transparent electrodes

Electromechanical properties of graphene transparent conducting films for flexible electronics

Carbon nanomaterials with metal grids were used as transparent conductive electrodes for liquid crystal displays (LCDs) to develop an indium tin oxide (ITO)-free device. We prepared LCDs with CNTs and graphene electrodes; however, the working voltage of the device with the CNT electrodes was high. The device with graphene electrodes had good performance, but not as good as devices with ITO electrodes. To improve the device performance, we applied a metal grid to the carbon nanomaterial to create low sheet-resistance transparent electrodes. The device with the graphene and metal grid transparent electrodes had a threshold voltage as low as 0.23 V/µm, which is similar to that of typical LCDs with ITO electrodes. The results show that a hybrid transparent conductive film with graphene and metal grid could be an alternative to ITO for developing ITO-free LCDs.

Yong Un Jung

Papers

High-transmittance liquid-crystal displays using graphene conducting layers

Organic photovoltaic devices with low resistance multilayer graphene transparent electrodes

Electromechanical properties of graphene transparent conducting films for flexible electronics

ITO-free transparent conductive films based on carbon nanomaterials with metal grid for liquid crystal displays

Electrical, Electronic and Optical Characterization of Multilayer Graphene Films for Transparent Electrodes