Carbazole derivatives are promising materials for the formation of self-assembled monolayers (SAMs), which serve as hole-transport layers in inverted perovskite solar cells. However, the relationship between their molecular structure, material properties, and photovoltaic device performance remains insufficiently understood, hindering the rational design of new materials. In this master’s thesis, we therefore synthesized and structurally characterized a series of carbazole-based SAM materials in which the substitution pattern of the carbazole core, the length and attachment site of the linker, and the type of anchoring group were varied. The effects of these structural modifications on the optical and electrochemical properties of the materials and their performance as hole-transport layers were evaluated using spectroscopic, electrochemical, and photovoltaic measurements. The electronic nature of the substituents on the carbazole core had the most pronounced effect on the optical and electrochemical properties, whereas the effect of the non-conjugated linker length was considerably less pronounced and showed no unambiguous trend. The best photovoltaic performance was achieved by devices incorporating asymmetrically substituted derivatives bearing a single methoxy group, in which the linker was attached through the carbazole nitrogen atom. Among the derivatives in which the linker was attached through an oxygen atom at the C2 position of the carbazole core, devices incorporating the N-methylated derivative with an ethyl linker achieved the best photovoltaic performance. This molecular design represents a promising platform for further functionalization of the carbazole core and optimization of the optoelectronic properties and photovoltaic performance of perovskite solar cells.
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