Achieving High Performance Molecular Rectification through Fast Screening Alkanethiol Carboxylate-Metal Complexes Electro-Active Unites

Achieving high rectifying performance of molecular scale diode devices through synthetic chemistry and device construction remain a formidable challenge due to the complexity of the charge transport process and the device structure. We demonstrated here high-performance molecular rectification realized in self-assembled monolayer (SAM) based device by low-cost and fast screening the electroactive units. SAMs of commercial available carboxylate terminated alkane thiols on gold substrate, coordinated with a variety of metal ions, structures denoting as Au-S-(CH2)n-1COO-Mm+ (Cn+Mm+), where n=11, 12, 13, 14, 16, 18 and Mm+=Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, were prepared and junctions were measured using a eutectic indiumgallium alloy top contact (EGaIn). The C18+Ca2+ and C18+Zn2+ junctions were found to afford a record high rectification ratio (RR) of 756 at ±1.5 V. Theoretical analysis based on single level tunneling model shows that optimized combination of the asymmetry voltage division, energy barrier and the coupling of carboxylate-metal complex with electrode. Our method described here represent a general strategy for fast, cheap and effective exploration of the metal complex chemical space for high-performance molecular diodes devices.

Ideal Current-voltage Characteristics and Rectification Performance of Molecular Rectifier under Single Level based Tunneling and Hopping Transport

In this work, we systematically studied the rectifying properties of molecular junction based on asymmetric tunneling and hopping charge transport in a single electronic state model using Landauer formula and Marcus theory. We first analyzed the asymmetric I-V characteristics and revealed distinct physical origins of the rectification under the two types of transports. We found significant difference in I-V characteristics of the two and the hopping transport can afford a much higher rectification ratio than tunneling. Next, the effect of key physical parameters on rectification performance under tunneling and hopping, like asymmetric factor, energy barrier, temperature and molecule-electrode coupling et al, were extensively evaluated, which provided a theoretical baseline for molecular diode design and performance modulation. At last, we further analyzed representative experimental results using the two models. We successfully reproduced the experimental results by adjusting the model parameters and revealed the coexistence of the tunneling and hopping processes in the ferrocene based molecular diode. The model method thus can work as powerful tool in mechanism analysis for the molecular rectification study.

Ideal Current-voltage Characteristics and Rectification Performance of Molecular Rectifier under Single Level based Tunneling and Hopping Transport

In this work, we systematically studied the rectifying properties of molecular junction based on asymmetric tunneling and hopping charge transport in a single electronic state model using Landauer formula and Marcus theory. We first analyzed the asymmetric I-V characteristics and revealed distinct physical origins of the rectification under the two types of transports. We found significant difference in I-V characteristics of the two and the hopping transport can afford a much higher rectification ratio than tunneling. Next, the effect of key physical parameters on rectification performance under tunneling and hopping, like asymmetric factor, energy barrier, temperature and molecule-electrode coupling et al, were extensively evaluated, which provided a theoretical baseline for molecular diode design and performance modulation. At last, we further analyzed representative experimental results using the two models. We successfully reproduced the experimental results by adjusting the model parameters and revealed the coexistence of the tunneling and hopping processes in the ferrocene based molecular diode. The model method thus can work as powerful tool in mechanism analysis for the molecular rectification study.

Molecular rectifiers based on five-coordinate iron(iii)-containing surfactants

The state-of-the-art of metallorganic-based molecular rectification is reviewed with an emphasis on asymmetric five-coordinate FeIII-containing surfactants in electrode|LB film|electrode assemblies.

Observation of current rectification by the new bimetallic iron(iii) hydrophobe [FeIII2(LN4O6)] on Au|LB-molecule|Au devices

A new bimetallic iron hydrophobe, [FeIII2(LN4O6)] (1) forms well-defined films used for current–voltage measurements and shows unquestionable molecular rectification.

Naphthoyl-Thiourea Thin Film as Potential OLED Featuring Methyl Pyridine Moiety

Thiourea derivatives have attracted great attention as potential materials to be used in molecular electronics application due to their fairly rigid p-system properties. Thus, in this studyN-((6-metylpyridin-3-yl)carbamothioyl)-1-naphtamide (NT) has been successfully designed, synthesized and characterized by typical spectroscopic techniques namely Infrared Spectroscopy (IR),1H and13C Nuclear Magnetic Resonance (NMR), UV-Vis, Four Point Probe to measure its conductivity and finally ab initio quantum mechanical evaluation at the theoretical level of DFT B3LYP/6-31G (d,p). In turn, NT was coated on the ITO substrate by using electrochemical deposition method. The electrical conductivity of this compound as a thin film exhibited good and ideal result which was 1.7x10-4Scm-1. Owing to this outstanding result, this single molecular system candidate has wide possibilities to be applied in many molecular rectification applications such as Organic Light Emitting diodes (OLED). Further investigation can be carried out by conducting and analyse the I-V curve to measure the efficiency of this compound and other similar molecular frameworks in the near future.