We enhance the efficiency of heterojunction organic solar cells by introducing a thin interfacial layer between the acceptor and donor layers. The interfacial layer energy levels are chosen to provide a gradient for charges crossing the interface, approximating a conventional p-n junction with three organic semiconductors. Devices with interfacial layers exhibit increased open circuit voltage (VOC) and increased short circuit current (JSC). The increase in VOC is due to a reduction in dark current and charge recombination. The increase in JSC is correlated with an increase in the conversion efficiency of excitons originating in the donor or acceptor layers. The interfacial layer destabilizes charge transfer states at the donor-acceptor interface, yielding reduced exciton recombination. The introduction of thin interfacial layers may prove to be an important probe of the physics of exciton separation in organic photovoltaic cells.
In this report, we present a general method for a continuous gas-phase synthesis of size-selected metal/multi layer graphene (MLG) core shell nanoparticles having a narrow size distribution of metal core and MLG shell for direct deposition onto any desired substrate kept under clean vacuum conditions. Evolution of MLG signature is clearly observed as the metal-carbon agglomerates get transformed to well defined metal/MLG core shell nanoparticles during their flight through the sintering zone. The growth takes place via an intermediate state of alloy nanoparticle (Pd-carbon) or composite nanoparticle (Cu-carbon), depending upon the carbon solubility in the metal and relative surface energy values. It has been also shown that metal/MLG nanoparticles can be converted to graphene shells. This study will have a large impact on how graphene or graphene based composite nanostructures can be grown and deposited in applications requiring controllable dimensions, varied substrate choice, large area and large scale depositions.
This review paper discusses the properties of nanomaterials, namely graphene, molybdenum disulfide, carbon nanotubes, and quantum dots for unique sensing applications. Based on the specific analyte to be detected and the functionalization techniques that are employed, some noteworthy sensors that have been developed are discussed. Further, biocompatible sensors fabricated from these materials capable of detecting specific chemical compounds are also highlighted for COVID-19 detection purposes, which can aid in efficient and reliable sensing as well as timely diagnosis.
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