Current rectification

Honciuc A, Jaiswal A, Gong A, Ashworth K, Spangler CW, Peterson IR, Dalton LR, Metzger RM (2005) Current rectification in a Langmuir-Schaefer monolayer of fullerene-bis-[4-diphenylamino-4 -(N-ethyl-N-2 -ethyl)amino-l,4-diphenyl-l,3-butadiene] malonate between Au electrodes. J Phys Chem B109 857-871... 

Figure 11.6. Crossed nanowire p-n diode, (a) A typical SEM image of a crossed NW p-n diode, (b) Current-voltage (I-V) relation of the crossed p-n diode. Linear or nearly linear I-V behavior of the p-type and n-type NWs indicates good contact between NWs and metal electrodes. I-V curves across the junction show clear current rectification, (c) An SEM image of an NW p-n diode array, (d) I-V behavior for a 4(p) x l(n) multiple junction array. [Adapted from Ref. 57.]... 

Fig. 10 (a) Schematic representation of the I-V measurement of the Cgo derivative based molecular rectifier, (b) I-V characteristics of the Langmuir-Blodgett film of the fullerene penta-pod showing current rectification at bias voltage of 1.0 V measured at different junction positions, with high rectification ratios (RR) registered at each junction. (Reprinted with permission from [98])... 

It is observed that in one half-period the minimal concentration indeed increases considerably more than it decreases in the other half-period. However, since the voltage is applied right where the concentration is at its minimum, the latter is always exactly in counterphase with the former. As a result there is no positive current rectification, despite the net increase of the minimal concentration during one period, as compared to the steady value. 

The arrows indicate the direction of the flow of electrons, thick short lines represent the aluminium or tantalum electrodes which allow the current to pass only when they act as cathodes. It will be seen from the diagram that cells 1 and 4 let electrons through from left to right, cells 2 and 3 act. in the opposite way tile elcctrones, therefore, always flow- towards B and are taken from. 1 which means that between these points, to which the electrical appliance is connected, there is a difference in D. C. voltage. Current rectification by means of this apparatus is not perfect its efficiency amounts to some (if)—70 per cent and with time it decreases still more. 

Historically, this is the material which really sparked interest in the solar photoelectrolysis of water. Early papers on TiCh mainly stemmed from the applicability of TiCh in the paint/pigment industry255 although fundamental aspects such as current rectification in the dark (in the reverse bias regime) shown by anodically formed valve metal oxide film/ electrolyte interfaces was also of interest (e.g., Ref. 52). Another driver was possible applications of UV-irradiated semiconductor/electrolyte interfaces for environmental remediation (e.g., Refs. 256, 257). 

Synthetic efforts focus on the molecular engineering of sensitisers that enhance charge separation at the oxide solution interface. The structural features of the dye should match the requirements for current rectification by analogy to the photofield effect in transistors, the gate for unidirectional electron flow from the electrolyte through the junction and into the oxide is opened by the photoexcitation of the sensitiser. The reverse charge flow, i.e. recapture of the electron by the electrolyte, could be impaired by judicious design of the sensitiser. The latter should form a... 

In Fig. 2 the current-density versus voltage (IV) characteristics are presented at room temperature and at 80 K. At 295 K the IV-characteristics exhibit a current rectification ratio of 8.105 for a bias variation from -1 to +1 V. Upon cooling, the reverse dark current-density at -2 Vbias decreases from 5.10 A/cm2 at 295 K to the sub nA/cm2 region at 80 K. From an Arrhenius plot of the reverse dark current-density... 

Kovarik, M.L., Zhou, K., Jacobson, S.C. Effect of conical nanopore diameter on ion current rectification. J. Phys. Chem. S113,15960-15966,2009. 

Chen, M., D. Nilsson, T. Kugler, M. Berggren, and T. Remonen. 2002. Electric current rectification by an all-organic electrochemical device. Appl Phys Lett 81 (11) 2011-2013. 

Fig. 5 A model for current rectification in a molecular junction Shown are the chemical potentials fii and /ur in the two electrodes, and the HOMO and LUMO levels of the donor, acceptor, and bridge. When the right electrode is positively biased, (as shown) electrons can hop from left to right as indicated by the dotted arrows. If the opposite bias can be set without affecting the electronic structure of the DBA system too much, the reverse current will be blocked.

Physically important cases for Case A in Figure 2 are diffusion of atoms or molecules through uniform membranes with finite or infinite thickness, solid-state diffusion, etc. Case B is important in connection with the directional transport problems such as the electronic conduction between two capacitors with some finite applied voltage, current rectification, viscous flow, etc. Case C is important in problems involving diffusion of molecules through a medium which is composed of two different kinds of atoms. 

Siwy, Z. S., Ion-current rectification in nanopores and nanotubes with broken symmetry. Advanced Eunctional Materials 2006,16, 735-746. 

White, H. S. Bund, A., Ion current rectification at nanopores in glass membranes. Langmuir 24, 2212-2218. 

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