engleski

Development of geopolymer network and following influence on conductivity properties

Alkali-activated aluminosilicates or so-called geopolymers (GP) have well cross-linked, 3D, fully polymerized aluminosilicate networks. In terms of pores, following properties could vary, and the most studied cations are potassium, sodium and even lithium. GPs are nowadays enforced as alternatives to concrete materials since their preparation minimally contributes to the energy and environmental problems worldwide. In particular, GPs give rise to new approach that could also boost energy savings. A particularly neat contribution in the overlapping fields of construction and energy materials could arise from the production of GP in the form of a paste that can be further developed into thin films. Such conductive and transparent thin-films could broaden the range of applicability in photovoltaic devices from horizontal mounting only to vertical mounting as well. In this work, we focus on chemical and (micro)structural changes occurring during the mullite-based geopolymer curing. Several factors influence changes, such as Al-to- Si ratio in the precursors and curing temperature. With this in mind, we study the conditions behind the geopolymerisation to obtain optimized samples characterised by XRD, DTA-TGA, FTIR, SEM and IS. Particular attention was paid to the NMR study of the evolution of the GP system as a function of curing temperature. Obtained results allowed a better understanding of the influence of chemical composition and homogeneity of constituents on the following structural, microstructural and electrical characteristics of studied samples. We have also demonstrated an interesting development involving a shift from relatively porous bulk to thin-film configuration, in order to spread the applicability of geopolymers for vertical facade photovoltaic systems.

geopolymers ; NMR study ; porous thin films ; solar cells

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