Donor−Acceptor Nanoarchitecture on Semiconducting Electrodes for Solar Energy Conversion

Abstract

Donor-acceptor molecules have been fabricated on a nanostructured semiconducting electrode for solar energy conversion (i.e., dye-sensitized bulk heterojunction solar cell). The device structure is similar to that of dyesensitized solar cells, but the top surface of the nanostructured semiconducting electrode is covered with donor-acceptor multilayers. Thus, initial charge separation takes place at the blend interface of the donor-acceptor, which is a typical characteristic of bulk heterojunction solar cells, whereas subsequent processes resemble those in dye-sensitized solar cells. In this novel solar cell, donor-nanocarbons (i.e., fullerenes and carbon nanotubes) have been successfully deposited electrophoretically or spin-coated onto nanostructured SnO 2 and TiO 2 electrodes that exhibit efficient photocurrent generation. The bottom-up self-organization of porphyrin and fullerene molecules onto the nanostructured electrodes has led to moderate cell performance with an incident photon-to-current efficiency of up to ∼60% and a power conversion efficiency of 1-2%. Importance of donor-acceptor nanoarchitecture on the nanostructured semiconducting electrodes is highlighted in terms of self-assembly of donor-acceptor molecules.

Dendrimer/inorganic nanomaterial composites: Tailoring preparation, properties, functions, and applications of inorganic nanomaterials with dendritic architectures

“…Generally, the key to employ QDs as a tool in biological systems is to achieve water solubility, biocompatibility, and photostability. As QDs themselves are hydrophobic, many kinds of methods have been exploited to prepare water-soluble QDs, for example, using capping ligands to modify the surface of QDs via a ligand-exchange method using thiol ligands [61]. Murphy and coworkers were the first to report using dendrimers to control the size and the solubility of QDs [52][53][54].…”

Paradigm shift from self-assembly to commanded assembly of functional materials: recent examples in porphyrin/fullerene supramolecular systems

“…Supramolecular structures consisting of fullerene (C 60 ) and porphyrin subunits are particularly attractive for the fabrication of functional nanomaterials, given the potential light-harvesting and photoinduced electron transfer properties of their constituents [65][66][67][68]. Only utilization of the functions of both components, porphyrin (electron-donor) and fullerene (electron-acceptor), might enable us to construct materials and systems for efficient photoelectron conversion.…”

Novel Electron Donor Acceptor Nanocomposites

“…Accordingly, the fabrication of donor-fullerene composites onto electrodes is a vital step for controlling the morphology of the composite assemblies on the electrode surface in molecular scale. Versatile methods such as Langmuir-Blodgett (LB) films [76], selfassembled monolayers (SAM) [77][78][79][80][81][82][83][84][85], layer-by-layer deposition [86,87], vacuum deposition [88,89], electrophoretic deposition [90][91][92][93][94][95][96][97][98][99], chemical adsorption, and spin coating [100][101][102][103][104][105][106][107], have been adopted to fabricate photoelectrochemical devices and solar cells.…”

“…A novel approach to enhance the light-harvesting efficiency was introduced into C 60 -based photoelectrochemical devices by electrophoretically depositing donor-C 60 composite clusters in acetonitrile/toluene (3/1, v/v) onto a semiconducting electrode [90][91][92]. Specifically, a toluene solution of donor-C 60 molecules is rapidly injected into acetonitrile to form donor-C 60 clusters due to the lyophobic nature in the mixed solvent.…”

“…Therefore, we can expect improvement of the photovoltaic properties by modulating both the structures of electrode surfaces and donor-acceptor multilayers [92]. Supramolecular assembly of donor-acceptor molecules is a potential approach to create a desirable phase-separated, interpenetrating network involving molecular-based nanostructured electron and hole highways.…”