Controlling Intermolecular Interactions at Interfaces: Case of Supramolecular Tuning of Fullerene's Electronic Structure

Abstract

It is demonstrated that systematic and designated control of supramolecular nanostructures via interfacial engineering enables (opto)electronic C60‐material properties to be widely adjusted. Interestingly, the lowest unoccupied molecular orbital (LUMO) energies of the same amphiphilic fullerene species are tuned up to 120 meV using supramolecular assembly, competitive to complete molecular change; cf. PC61BM to PC71BM causes a change of 200 meV. Morphology control is achieved through different thin‐film production techniques involving molecular assembly at interfaces, including liquid–liquid interfacial precipitation (LLIP), and Langmuir–Blodgett technique at air–water interface. LLIP enables supramolecularly ordered extended surfaces, yielding the least electronically stable LUMO (ELUMO = −4.28 eV). After qualitatively explaining the observed electrochemical LUMO energy variation for these assemblies with varied molecular packing and aggregate dimensions, an analytical equation is proposed, connecting morphological parameters with LUMO energies with prospects in supramolecular chemistry. To demonstrate the applicability of supramolecular structure–electronic property relations and of supramolecular structure fabrication protocols established in this work to tailor device properties, amorphous‐Si/fullerene hybrid solar cells are built and characterized. It is found that the supramolecular structure variation can be successfully translated to the solar cells, giving rise to a prototype linear relation between LUMO energy and open‐circuit voltage.

Functional Carbazole‐Fullerene Complexes: A New Perspective of Carbazoles Acting as Nano‐Octopus to Capture Globular Fullerenes

“…Integrated fullerene host‐guest complexes with highly‐ordered supramolecular arrangements have attracted increasing interest in many application fields, including photovoltaics, [1] superconductors, [2] pharmaceutics, [3] and organic electronics [4] . In particular, fullerene possesses unique features, which have promoted its complexation challenges and its uniqueness, in terms of spherical shape, electronic structure, [5] high symmetry, [6] and polarizability [7] . Furthermore, the mixed interaction involving partial charge transfer during synthesis contributes to the final stabilization energy, referred to kinetic studies of multi‐component systems [8] .…”

Macroscopic Quantum Electrodynamics and Density Functional Theory Approaches to Dispersion Interactions between Fullerenes

“…In addition to molecular structure, [1,2,3,4] particularly the supramolecular structure essentially determines ensemble properties, such as the UV-vis absorption [5,6,7] and emission [2,8] spectrum, charge transfers [9], conductivity [10,11,12] and further properties [13,14]. Archetype examples are formations of H-or J-aggregates from dipolar dyes, which are accompanied by pronounced changes in the UV-vis absorption spectra.…”

“…In this work, we will apply both methods to determine vdW-potentials and spectral properties of fullerene dimers, particularly in dependence on molecular rotation, translation and electronic excitation. We choose fullerenes as case study because their supramolecular structures are known to heavily influence photonic [6] and electronic [14,21] material properties. [22,23,24] Fullerenes (both C 60 and C 70 with their derivatives) find application in a plethora of different fields like nanomedicine [25], hydrogen storage [26], bio-organics [27] and photodynamic therapy [28], but particularly as n-type semiconductors in several branches of organic electronics [14,29,30,31].…”

Orientational Dependence of the van der Waals Interactions for Finite-Sized Particles

“…Typically, the interacting particles are considered to be point-like. However, current investigations and applications deal with large molecules and clusters on small separations, such as fullerenes (C 60 and C 70 with their derivatives) that find application in a plethora of different fields like nanomedicine 2 , hydrogen storage 3 , bio-organics 4 and photodynamic therapy 5 but particularly as n-type semiconductors in several branches of organic electronics [6][7][8][9] . In such experiments and applications the separation of the considered particles is of the same order of magnitude as their spatial dimension.…”