Photocurrent Generation in Multilayer Self‐Assembly Films Fabricated from Water‐Soluble Poly(phenylene vinylene)

Abstract

A novel, water-soluble, cationic PPV derivative poly[(2,5-bis(3-bromotrimethylammoniopropoxy)-phenylene-1,4-divinylene)-alt-1,4-(2,5-bis(2-(2-hydroxyethoxy)ethoxy))phenylene vinylene] (BH-PPV) has been synthesized by a Heck coupling reaction. Multilayered assemblies of the BH-PPV and the sodium salt of hexa(sulfobutyl)fullerenes (C(60)-HS) were fabricated successfully by an alternate deposition technique. The multilayer structures were studied by UV/Vis spectroscopy, small angle X-ray diffraction, and atomic force microscopy. The photoinduced charge transfer property of the self-assembled multilayer film was also measured by a three-electrode cell technique. A steady and rapid cathodic 5.5 microA cm(-2) photocurrent response was measured as the irradiation of the multilayer film was switched on and off. Importantly, the response of on/off cycling is prompt and reproducible. A possible mechanism for the electron-transfer process is proposed.

Design of Multilayered Nanostructures and Donor–Acceptor Interfaces in Solution‐Processed Thin‐Film Organic Solar Cells

“…10 nm by the layer-by-layer deposition technique, which distinguishes it from previous approaches in which all functional layers were prepared by layer-by-layer deposition. [29][30][31][32] Indeed, FF of our devices decreased to less than 0.25 when the light-harvesting layer was thicker than 30 nm. We should note that our devices were fabricated in air with wet processes and their J-V characteristics were also measured in air.…”

“…Thus, thin-film organic solar cells that utilize these advantages of the layer-by-layer technique have been reported by some groups. [29][30][31][32][33][34] However, it has not been fully exploited in organic solar cells to date and the performance of the devices has remained poor, with a low power conversion efficiency of <0.05%, partly because of the low charge mobility. [33] Recently, we reported an improvement in conductive and photovoltaic properties of a poly( p-phenylenevinylene) (PPV)-based layer-by-layer thin-film device by low-temperature conversion.…”

Poly(phenylenevinylenes)

“…The mild conditions associated with the Heck coupling allow the presence of various functional groups, making it an attractive tool in the preparation of various functional PPVs (Table 4.4). For example, the water-soluble 44 has been prepared, which can form multilayer self-assembly films with hexa(sulfobutyl)fullerences [89]. Resulting from the interaction between the donor (PPV) and acceptor (fullerence) layers, the assembled multilayer films exhibit a steady and rapid photocurrent response upon light irradiation (at ∼430 nm).…”

Nanoconfined Polyelectrolyte Multilayers

“…[2][3][4][5] Charged macromolecules, also known as polyelectrolytes, adsorb easily onto surfaces due to electrostatic, van der Waals, and/or hydrogen-bonding interactions. This makes them ideal candidates as a molecular glue to build complex functional systems in a layer-by-layer fashion, such as magnetic [6] and catalytic [7] films, memoryswitching devices, [8] nacre mimics, [9] optical coatings, [10] superhydrophobic [11] and biocompatible active [12,13] surfaces, photoactive systems, [14] carbon nanotube assemblies, [15] and so on.[4]Attempts to laterally control the size of such assemblies have been previously reported, but have so far been limited to the micrometer-scale and above. [16] Of challenging interest would be to succeed in controlling multilayer build-up in the nanometer range, when the size of the macromolecules is similar to the size of the objects to be built.…”