Influence of Molecular Conformation on Electron Transport in Giant, Conjugated Macrocycles

Abstract

We describe here the direct connection between the molecular conformation of a conjugated macrocycle and its macroscopic charge transport properties. We incorporate chiral, helical perylene diimide ribbons into the two separate macrocycles as the n-type, electron transporting material. As the macrocycles' films and electronic structures are analogous, the important finding is that the macrocycles' molecular structures and their associated dynamics determine device performance in organic field effect transistors. We show the more flexible macrocycle has a 4-fold increase in electron mobility in field effect transistor devices. Using a combination of spectroscopy and density functional theory calculations, we find that the origin of the difference in device performance is the ability of more flexible isomer to make intermolecular contacts relative to the more rigid counterpart.

Supramolecular Assemblies for Electronic Materials

“…In fact, the existence of supplementary intermolecular π–π aromatic stacking interactions for its recognition are indicated by downfield shifts of protons on the exohedral phenyl ring of the PC 61 BM (Figure S6.3). In contrast to the case of PBPB , weak or negligible fullerene binding was observed with analogous PDI‐based hosts containing either a larger cavity ( DBDB , Figure S6.8) or acyclic framework ( acyclic ‐ PDI , Figure S6.7) …”

“…In contrast, PDI‐based conjugated macrocycles are a relatively new class of organic electronic material that possess several advantages as n‐type materials including: synthetic flexibility (allowing tuneable electronic properties); extensive π‐conjugation; and shape persistent cavities that facilitate guest incorporation and sensing . Indeed, conjugated macrocycles form the electron‐transporting material in organic field effect transistors (OFETs), photodetectors, and photovoltaics …”

“…We collected the data for these transfer curves using a source‐drain voltage of 80 V while sweeping the gate voltage from −20 V to 80 V (Supporting Information, section 3). We find the mobility of the complex [ PBPB ]⊃[ PC 61 BM ] is over five times that of neat PBPB (8.0×10 −3 cm 2 V −1 s vs. 1.5×10 −3 cm 2 V −1 s) and also greater than the majority of our previous PDI‐based macrocyclic and acyclic n‐type electronic materials . The formation of a robust [ PBPB ]⊃[ PC 61 BM ] complex and the strong electronic interaction between host and guest is integral to enhancing the mobility of the resulting supramolecular material.…”

“…cilitateg uest incorporation and sensing. [12,13] Indeed,c onjugated macrocycles form the electron-transporting materiali no rganic field effect transistors( OFETs), [14][15][16] photodetectors, [17] and photovoltaics. [14] Here we utilize the shape and functionalg roup complementarity between theset wo electronicc omponentst of orm a robusth ost-guest complex that, as ar esult of this supramolecular chemistry,c an be readily processed to generate as uperior electronic material.…”

“…[36] In fact, the existence of supplementary intermolecular p-p aromatic stacking interactions for its recognition are indicated by downfield shifts of protonso nt he exohedral phenyl ring of the PC 61 BM (Figure S6.3). In contrastt ot he case of PBPB,w eak or negligible fullereneb inding was observed with analogous PDI-based hosts containing either al arger cavity (DBDB,F igure S6.8) [15] or acyclic framework (acyclic-PDI, Figure S6.7). [14] We used mass spectrometry (ESI), to further characterize and quantify the fullerene recognitionp roperties of macrocycle PBPB.S ignals corresponding to the complex [PBPB]'[Fullerene]w ere found from analysis of each of the NMR titration solutions at their end point (Supporting Information, section4).…”