Low-dimensional materials for organic electronic applications
Thesis Defense: Sumit Beniwal
10:00 am
Jorgensen Hall Room: 245
Abstract:
This thesis explores the self-assembly, surface interactions and electronic properties of functional organic molecules that have potential applications in organic electronics. Three classes of molecules - organic ferroelectric, spin-crossover complex, 2D semiconductors, have been studied through scanning tunneling microscopy and surface-sensitive spectroscopic methods. The scientific goal of this thesis is to understand the ferroelectricity and magnetic properties of the molecules in low-dimensional (2D) configurations and the influence of substrate on these properties. First, a H-bonded organic ferroelectric, the 3-Hydroxyphenalenone, is studied on three noble metal substrates. It is demonstrated how a variety of different assemblies including 1D chains, pi-pi stacked structures and chiral network can be fabricated using the substrate as a growth parameter. Second, the self-assembly of Fe(II) spin crossover complex, [Fe(H2B(pz)2)(bipy)], is studied on Au(111) substrate. This organic complex can be reversibly switched between paramagnetic high-spin (S=2) and diamagnetic low-spin state (S=0) in the bulk. The magnetic and electronic properties of this complex were found to be drastically influenced by the substrate. Third, the self-assembly of Bis-BN Cyclohexane (B2C2N2H12) is investigated on Ir(111) substrate. The covalent bonding between dehydrogenated Bis-BN Cyclohexane molecules led to the discovery of a new 2D BCN containing material, which is in analogy to graphene and h-BN, but with the useful band gap of 0.9 eV.
This thesis explores the self-assembly, surface interactions and electronic properties of functional organic molecules that have potential applications in organic electronics. Three classes of molecules - organic ferroelectric, spin-crossover complex, 2D semiconductors, have been studied through scanning tunneling microscopy and surface-sensitive spectroscopic methods. The scientific goal of this thesis is to understand the ferroelectricity and magnetic properties of the molecules in low-dimensional (2D) configurations and the influence of substrate on these properties. First, a H-bonded organic ferroelectric, the 3-Hydroxyphenalenone, is studied on three noble metal substrates. It is demonstrated how a variety of different assemblies including 1D chains, pi-pi stacked structures and chiral network can be fabricated using the substrate as a growth parameter. Second, the self-assembly of Fe(II) spin crossover complex, [Fe(H2B(pz)2)(bipy)], is studied on Au(111) substrate. This organic complex can be reversibly switched between paramagnetic high-spin (S=2) and diamagnetic low-spin state (S=0) in the bulk. The magnetic and electronic properties of this complex were found to be drastically influenced by the substrate. Third, the self-assembly of Bis-BN Cyclohexane (B2C2N2H12) is investigated on Ir(111) substrate. The covalent bonding between dehydrogenated Bis-BN Cyclohexane molecules led to the discovery of a new 2D BCN containing material, which is in analogy to graphene and h-BN, but with the useful band gap of 0.9 eV.