Separation of photogenerated electron-hole pairs in a molecular three-layer structure

Light‐Induced Hole Transfer Across a Langmuir‐Blodgett Double‐Layer Membrane with a Short Tunneling Barrier

“…This is a well known feature of dye sensitized hole injection into an anthracene insulator electrode at moderate dye coverage [13]. The redox potentials of the reactants allow for hole transfer from the optically excited FIII species to the anthracene moiety in 2 A 7 [2]. Fig.…”

“…Employing anthracene as part of the hydrophobic tail in 2A7 leads to a much shorter alkane chain tunneling barrier for charge transfer across the membrane than in other types of Langmuir-Blodgett membranes where the active components are located exclusively in the hydrophilic parts of the molecules [8, 91. Two further monolayers of arachidaic acid were deposited before the aqueous electrolyte contact was applied on top as has been described in detail before [2,5]. Excitation spectrum and electric field strength dependence of the stationary photocurrent have been measured in a set-up also described in detail before ClOl.…”

“…P-TKN shows no chemical change under the influence of light [3 -51 and several mechanisms have been discussed for the photochromy of P-TKN. First it was proposed that the photochromy is connected t o a change of the "physical crystalline state" of the compound and this assumption was supported by the observation of Marckwald [2], who found a phase transition of the photochromic P-TKN t o a non-photochromic high temperature phase.…”

“…The necessary alignment of suitable reactive molecules in a macroscopic system can be achieved when the molecules are firstly modified to become amphiphilic and secondly assembled with the Langmuir-Blodgett technique [l]. This way a device is build where light-induced downhill electron-hole pair separation can occur across a membrane of molecular thickness but with a planar surface of macroscopic dimensions [2]. The molecular alignment in the Langmuir-Blodgett monolayer is significant and can result even in the formation of crystallites in the layer [3].…”

NQR Spectroscopy and Structure of Photochromic 2,3,4,4‐Tetrachloro‐1‐oxo‐1,4‐dihydronaphthaline and 2,4,4‐Trichloro‐1,4‐dihydronaphth[1,8‐cd]isothiazole‐1,1‐dioxide

“…In 1888 Zincke [l] reported that crystals of 2,3,4,4-tetrachloro-1 -oxo-1,4-dihydronaphthaIine @ (P-TKN) change their colour under the influence of daylight from colourless t o amethystine. Marckwald [2] recognized the reversibility of this effect which was called phototropy. If a coloured crystal of p-TKN is kept in the dark the red-violet colour disappears a t room temperature within a day.…”