Molecular Switches: Optoelectronic components based on a dye-sensitized TiO2 solar cell

Apr 24, 2006

Electronic components must continue to get smaller: Miniaturization has now reached the nanometer scale (10-9 m). In this tiny world, classic semiconductor technology is reaching its limits. We now need switches and other devices whose dimensions are on the scale of individual molecules. The difficulty with this is in the addressability and compatibility of molecular systems with the available nanoelectronic components. Until now, all molecular systems require at least one step in which a solution must be injected into the system and then rinsed out again, which is time-consuming.

L. Furtado, K. Araki, H. E. Toma, and co-workers at the University of São Paulo in Brazil describe for the first time an optoelectronic molecular gate that directly absorbs light and gives off electrical impulses.

The gate consists of a glass electrode onto which a thin, nanocrystalline film of TiO2 is deposited. A dye, in this case a cluster of three ruthenium–pyrazinecarboxylate complexes, is adsorbed to this surface. A platinum counter electrode is used, and the space between the electrodes is filled by an electrolyte solution of I3-/I2 in CH3CN.

When this gate is irradiated with light, electrons are excited, which leads to charge separation and a flow of current. The direction of the current changes depending on the wavelength of the light irradiating the system: at 350 nm, the electrons flow from the Pt electrode to the glass electrode; at 420 nm, they flow the other way.

At 350 nm, the TiO2 layer absorbs the light and gives off electrons to the underlying glass electrode. To compensate, the corresponding number of electrons is removed from the ruthenium cluster, which replaces them with electrons from the Pt electrode. At 420 nm, however, the ruthenium complexes are induced to give off electrons to the Pt electrode, which are re-supplied from the TiO2 layer.

The result is a switch that is not only turned on and off by light, but whose signal can change direction on the basis of the wavelength of light used.

Citation: Angewandte Chemie International Edition 2006, 45, No. 19, 3143–3146, doi: 10.1002/anie.200600076

Source: Angewandte Chemie

Explore further: Graphene imperfections key to creating hypersensitive 'electronic nose'

add to favorites email to friend print save as pdf

Related Stories

Team improves solar-cell efficiency

Sep 19, 2014

New light has been shed on solar power generation using devices made with polymers, thanks to a collaboration between scientists in the University of Chicago's chemistry department, the Institute for Molecular ...

Future of energy storage

Sep 16, 2014

MIT professor Fikile Brushett is in the process of taking the power generated by wind and solar, chemically lashing it to molecules derived from flora and fauna, and storing it in liquids until it's needed ...

Study sheds new light on why batteries go bad

Sep 14, 2014

A comprehensive look at how tiny particles in a lithium ion battery electrode behave shows that rapid-charging the battery and using it to do high-power, rapidly draining work may not be as damaging as researchers ...

X-ray imaging paves way for novel solar cell production

Sep 09, 2014

The sharp X-ray vision of DESY's research light source PETRA III paves the way for a new technique to produce cheap, flexible and versatile double solar cells. The method developed by scientists from the ...

First graphene-based flexible display produced

Sep 05, 2014

(Phys.org) —A flexible display incorporating graphene in its pixels' electronics has been successfully demonstrated by the Cambridge Graphene Centre and Plastic Logic, the first time graphene has been used ...

Recommended for you

Scientists grow a new challenger to graphene

11 hours ago

A team of researchers from the University of Southampton's Optoelectronics Research Centre (ORC) has developed a new way to fabricate a potential challenger to graphene.

Nanotubes help healing hearts keep the beat

11 hours ago

(Phys.org) —Carbon nanotubes serve as bridges that allow electrical signals to pass unhindered through new pediatric heart-defect patches invented at Rice University and Texas Children's Hospital.

User comments : 0