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The solution to the all polymer solar cell that breaks the 10% efficiency barrier keeps getting closer, with ever more scrutiny on each component in the active device for better performance. Much effort has been expended on the hole transport layers and photo-active polymer blends in these solution deposited photovoltaic cells. In this study we examine the merits of incorporating solution deposited metal oxide and hybrid metal oxide/reduced graphene oxide (RGO) based electron transport layers (ETL) with a view to providing further improvements to the PV cell architecture. Low bandgap active layer blends of [3,4-b]thiophene/benzodithiophene (PTB7) and [6,6]-phenyl C70 butyric acid methyl fullerene (PC 70 BM) with efficiencies in excess of 7% are fabricated and the performance of four different ETL material systems based on TiO 2 , ZnO, TiO 2 /RGO, ZnO/RGO are compared to thermally evaporated optimised reference bathocuproine (BCP) PV devices. Hybrid metal oxide/RGO ETL incorporated solution processed devices show an improved device performance compared to metal oxide only devices, with the performance comparable to the thermally evaporated BCP with fill factors of 68% and short circuit currents reaching 15 mA/cm 2 . The enhanced performance of the RGO incorporated hybrid ETL points the way for novel transport layers for all solution processed devices. BodyGrowing concerns with regards to the diminishing supply of fossil fuels and the impact of such non-renewables on global warming has made solar energy generation an important area of research. Of the many types of solar-energy converting systems, organic photovoltaics have attracted significant interest due to their low cost, light weight and the printable nature on flexible substrates.

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Graphene oxide (GO) is becoming increasingly popular for organic electronic applications. We present large active area (0.64 cm^2), solution processable, poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:[6,6]-Phenyl C71 butyric acid methyl ester (PCDTBT:PC70BM) organic photovoltaic (OPV) solar cells, incorporating GO hole transport layers (HTL). The power conversion efficiency (PCE) of ~5% is the highest reported for OPV using this architecture. A comparative study of solution-processable devices has been undertaken to benchmark GO OPV performance with poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) HTL devices, confirming the viability of GO devices, with comparable PCEs, suitable as high chemical and thermal stability replacements for PEDOT:PSS in OPV

We report on the synthesis of two and three dimensional carbonaceous sponges produced directly from graphene oxide (GO) into which functionalized iron nanoparticles can be introduced to render it magnetic. This simple, low cost procedure, wherein an iron polymeric resin precursor is introduced into the carbon framework, results in carbon-based materials with specific surface areas of the order of 93 and 66 m(2) g(-1), compared to approx. 4 m(2) g(-1) for graphite, decorated with ferromagnetic iron nanoparticles giving coercivity fields postulated to be 216 and 98 Oe, values typical for ferrite magnets, for 3.2 and 13.5 wt% Fe respectively. The strongly magnetic iron nanoparticles are robustly anchored to the GO sheets by a layer of residual graphite, on the order of 5 nm, formed during the pyrolysis of the precursor material. The applicability of the carbon sponges is demonstrated in their ability to absorb, store and subsequently elute an organic dye, Rhodamine B, from water as required. It is possible to regenerate the carbon-iron hybrid material after adsorption by eluting the dye with a solvent to which it has a high affinity, such as ethanol. The use of a carbon framework opens the hybrid materials to further chemical functionalization, for enhanced chemical uptake of contaminants, or co-decoration with, for example, silver nanoparticles for bactericidal properties. Such analytical properties, combined with the material's magnetic character, offer solutions for environmental decontamination at land and sea, wastewater purification, solvent extraction, and for the concentration of dilute species.