A hybrid ac/dc microgrid is a more complex but practical network that combines the advantages of an AC and a DC system. The main advantage of this network is that it connects both alternating current and direct current networks via an interlinking converter (IC) to form a unified distribution grid. The hybrid microgrid (HMG) will enable the direct integration of both alternating current (AC) and direct current (DC) distributed generators (DGs), energy storage systems (ESS), and alternating current and direct current (DC) loads into the grid. The alternating current and direct current sources, loads, and ESS are separated and connected to their respective subgrids primarily to reduce power conversion and thus increase overall system efficiency. As a result, the HMG architecture improves power quality and system reliability. Planning a hybrid microgrid entails estimating the capacities of DGs while taking technical, economic, and environmental factors into account. The hybrid ac-dc microgrid is regarded as the distribution network of the future, as it will benefit from both ac and dc microgrids. This thesis presents a general architecture of a hybrid ac-dc microgrid, which includes both planning and design. The goal of the Hybrid ac-dc microgrid planning problem is to maximise social welfare while minimising total planning costs such as investment, maintenance, and operation costs. This configuration will assist Hybrid microgrid planners in estimating planning costs while allowing them to consider any type of load ac/dc and DER type. Finally, this thesis identifies the research questions and proposes a future research plan.

We demonstrate a new approach for fabricating alternating current driven organic electroluminescent devices using the concept of doping in organic semiconductors. Doped charge transport layers are used for generation of charge carriers within the device, hence eliminating the need for injecting charge carriers from external electrodes. The device is an organic-inorganic hybrid: We exploit the mechanical strength and chemical stability of inorganic semiconductors and combine it with better optical properties of organic materials whose emission color can be chemically tuned so that it covers the entire visible spectrum. The device consists of an organic electroluminescence (EL) layer composed of unipolar/ambipolar charge transport materials doped with organic dyes (10 wt% ) as well as molecularly doped charge generation layers enclosed between a pair of transparent insulating metal oxide layers. A transparent indium doped tin oxide (ITO) layer acts as bottom electrode for light outcoupling and Aluminium (Al) as top reflective electrode. The electrodes are for applying field across the device and to charge the device, instead of injection of charge carriers in case of direct current (DC) devices. Bright luminance of up to 5000 cd m-2 is observed when the device is driven with an alternating current (AC) bias. The luminance observed is attributed to charge carrier generation and recombination, leading to formation of excitons within the device, without injection of charge carriers through external electrodes.

We demonstrate a new approach for fabricating alternating current driven organic electroluminescent devices using the concept of doping in organic semiconductors. Doped charge transport layers are used for generation of charge carriers within the device, hence eliminating the need for injecting charge carriers from external electrodes. The device is an organic-inorganic hybrid: We exploit the mechanical strength and chemical stability of inorganic semiconductors and combine it with better optical properties of organic materials whose emission color can be chemically tuned so that it covers the entire visible spectrum. The device consists of an organic electroluminescence (EL) layer composed of unipolar/ambipolar charge transport materials doped with organic dyes (10 wt% ) as well as molecularly doped charge generation layers enclosed between a pair of transparent insulating metal oxide layers. A transparent indium doped tin oxide (ITO) layer acts as bottom electrode for light outcoupling and Aluminium (Al) as top reflective electrode. The electrodes are for applying field across the device and to charge the device, instead of injection of charge carriers in case of direct current (DC) devices. Bright luminance of up to 5000 cd m-2 is observed when the device is driven with an alternating current (AC) bias. The luminance observed is attributed to charge carrier generation and recombination, leading to formation of excitons within the device, without injection of charge carriers through external electrodes.