Speaker
Description
Carbazole-based self-assembled monolayers (SAMs), such as CbzNaph, have attracted interest for their hole-selective performance in inverted perovskite solar cells [1,2]. This is attributed to their large dipole moments and strong π–π stacking interactions. Despite their improved performance, they still face long-term stability challenges due to their susceptibility to solvent-induced reconstruction [3]. This prompts a search for durable SAMs to extend lifetime and minimise the environmental footprint for perovskite photovoltaics. CbzNaph molecules can be viewed as either substituted or heavily functionalized adducts of a helical dibenzo[c,g]carbazole core, and derivatives with electron-withdrawing peripheral groups exhibit substantially higher interfacial polarisation than those with neutral substituents. The activity of a molecule depends on its molecular properties; thus, understanding them in detail is important for designing molecules with better electronic and optical properties. The current study focuses on CbzNaph derivatives in which the periphery is systematically substituted with strong electron-withdrawing moieties (cyanovinyl, halogen) alongside UV-reactive crosslinking groups (allyl, azide). The goal of this study is to identify how these targeted structural modifications influence molecular behaviour and property investigation across different media.
Computational studies were performed on selected derivatives, utilising density functional theory (DFT) with implicit solvation models to simulate both vacuum and polar solvent environments. The ongoing study additionally investigates the binding energies of the derivatives on model ITO surfaces, with the aim of quantifying how these modifications modulate adsorption strength and enhance resistance to solvent-induced desorption and reconstruction.
The results show that variation in peripheral functionalization significantly influences the molecular properties under consideration. These include a systematic deepening of HOMO levels for hole extraction, a maintained wide bandgap for electron blocking, and a profound, media-dependent increase of molecular dipole moments.
Keywords: self-assembled monolayers, carbazole derivatives, inverted perovskite solar cells, density functional theory, hole-selective contacts.
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