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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.

A method for the synthesis of metal nanoparticles coatings for plasmonic solar cells which can meet large scale industrial demands is demonstrated. A UV pulsed laser is utilized to fabricate Au and Ag nanoparticles on the surface of polymer materials which forms the substrates for plasmonic organic photovoltaic devices. Control of the particles' size and density is demonstrated. The optical and electrical effects of these embedded particles on the power

Incorporating plasmonic nanoparticles in organic photovoltaic (OPV) devices can increase the optical thickness of the organic absorber layer while keeping its physical thickness small. However, trade-offs between various structure parameters have caused contradictions regarding the effectiveness of plasmonics in the literature, that have somewhat stunted the progressing of a unified theoretical understanding for practical applications. We examine the o p t i c a l e n h a n c e m e n t m e c h a n i s m s o f p r a c t i c a l PCDTBT:PC 70 BM OPV cells incorporating metal nanoparticles. The plasmonic near-and far-field contributions are differentiated, with spectrum-and space-wide current enhancements found in the plasmon scattering regime and spectrum-and space-specific current enhancements in the near-field regime. A remarkable system complexity is revealed, where the plasmonic enhancement trends change and even reverse by simple changes in the device geometry. This accounts for many of the contradictory results published in the literature on plasmonic effects in OPVs. By exploring the full structural parameter phase-space we are able to now propose a unified representation that intuitively explains literature findings and trends. Our results show that an already optimized PCDTBT:PC 70 BM cell can be further optically enhanced by plasmonic effects by at least 20% with the incorporation of Ag nanoparticles.

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