Three-Dimensional Graphene Nanostructures

Abstract

This Communication details the implementation of a new concept for the design of high-performance optoelectronic materials: three-dimensional (3D) graphene nanostructures. This general strategy is showcased through the synthesis of a three-bladed propeller nanostructure resulting from the coupling and fusion of a central triptycene hub and helical graphene nanoribbons. Importantly, these 3D graphene nanostructures show remarkable new properties that are distinct from the substituent parts. For example, the larger nanostructures show an enhancement in absorption and decreased contact resistance in optoelectronic devices. To show these enhanced properties in a device setting, the nanostructures were utilized as the electron-extracting layers in perovskite solar cells. The largest of these nanostructures achieved a PCE of 18.0%, which is one of the highest values reported for non-fullerene electron-extracting layers.

Dimensional Control in Contorted Aromatic Materials

“…Triptycene, the three‐dimensional scaffold, though not formally conjugated, exhibits through‐space electron delocalization when coupled to three highly stable PDI subunits. This has been shown previously by electron paramagnetic resonance (EPR) spectroscopy . This three‐dimensional electronic pathway allows for these exceptional electrochemical kinetics and additionally provides intrinsic porosity to the polymer architecture.…”

“…The studies described above have established that the incorporation of rigid three‐dimensional elements into electronic materials provides emergent characteristics capable of significantly enhancing material performance . It has also been established that deviation from aromatic planarity does not preclude long‐range interaction and can, in some cases, enhance it .…”

“…Fullerene, a three‐dimensional contortion of graphene and the quintessential electron acceptor for organic optoelectronic devices, has been investigated for enhanced interlayer transport properties resulting from its three‐dimensional geometry . We devised a synthetic strategy to generate 3D GNR nanostructures (Figure a) . We successfully attached three trimeric PDI GNRs via a Suzuki coupling to a central triptycene hub and then fused the resulting three‐dimensional graphene nanostructure in a visible light flow photocyclization to generate Nanostructure 3 (Figure d).…”

“…The materials can be easily tuned from a battery‐like state ( Porous‐1 ; capable of storing more charge at low current) to a capacitor‐like state (Porous‐2 ; superior charge cycling at high rates) via the same visible‐light flow photocyclization we have reported previously . These tunable capacitive states can be analysed using electrochemical impedance spectroscopy (EIS) (Figure c) to derive the contributions of pseudocapacitance and electrical double‐layer capacitance in the device.…”

Triptycene‐based fluorescent polymers with pendant alkyl chains: interaction with fullerenes and morphology of thin films

“…Triptycene and pentiptycene molecules are members of the iptycene family, with the former being the simplest member bearing three phenyl rings connected via a [2.2.2] bicyclic ring. Materials bearing the iptycene motif demonstrate desirable properties such as good organosolubility, high intrinsic microporosity, high thermal stability, improved photostability, enhanced fluorescence quantum yields and others . Consequently, such polymers (derived from iptycene monomers) have found application in the design of gas separation membranes, organic photovoltaic devices, liquid crystals, .…”