Controlling Vertical and Lateral Electron Migration Using a Bifunctional Chromophore Assembly in Dye-Sensitized Photoelectrosynthesis Cells

Abstract

Integration of photoresponsive chromophores that initiate multistep catalysis is essential in dye-sensitized photoelectrosynthesis cells and related devices. We describe here an approach that incorporates a chromophore assembly surface-bound to metal oxide electrodes for light absorption with an overlayer of catalysts for driving the half-reactions of water splitting. The assembly is a combination of a core-twisted perylene diimide and a ruthenium polypyridyl complex. By altering the connection sequence of the two subunits in the assembly, in their surface-binding to either TiO or NiO, the assembly can be tuned to convert visible light into strongly oxidizing equivalents for activation of an electrodeposited water oxidation catalyst (NiCoO ) at the photoanode, or reducing equivalents for activation of an electrodeposited water reduction catalyst (NiMoS ) at the photocathode. A key element in the design of the photoelectrodes comes from the synergistic roles of the vertical (interlayer) charge transfer and lateral (intralayer) charge hopping in determining overall cell efficiencies for photoelectrocatalysis.

Excitation energy-dependent photocurrent switching in a single-molecule photodiode

“…With those devices, electrical and electronic processes can be modified by varying functional electrode elements and integrating individual molecular components that respond to external stimuli, such as electrochemical redox potentials, optical excitation, and magnetic fields (3)(4)(5)(6)(7). Photoresponsive molecular diodes have been used in dye-sensitized photoelectrodes to generate electron-hole pairs for catalytic and optoelectronic applications (8)(9)(10)(11)(12)(13)(14). They convert solar energy into electrical signals and chemical energy by transfer of photogenerated electrons following optical excitation.…”

A Charge‐Separated State that Lives for Almost a Second at a Conductive Metal Oxide Interface

“…[7,10a,b,h] While these and most previous examples utilized non-aqueous solutions,arelated assembly has only recently been reported in aqueous solution. [11] Here,t his photoelectrode design produced stable and long-lived transient charge separation at at ransparent conductive oxide interface in aqueous solution, ar esult that opens up the possibility for future use of conductive interfaces for solar energy conversion applications such as water splitting.…”

“…Left:t he chemicalcapacitance of each component of the photoelectrodeassembly, extracted from the spectroelectrochemical data given in Figure 1b.Also given for each component is the equilibriumpotential where equal numbers of each half of the couple were present that was taken as an estimate of the formal reduction potential. [11] Here,t his photoelectrode design produced stable and long-lived transient charge separation at at ransparent conductive oxide interface in aqueous solution, ar esult that opens up the possibility for future use of conductive interfaces for solar energy conversion applications such as water splitting. assemblies.…”

Perylene Diimide‐Based Electron‐Transporting Material for Perovskite Solar Cells with Undoped Poly(3‐hexylthiophene) as Hole‐Transporting Material

“…Because the synthesis of fullerene‐based ETMs is longwinded and complicated owing to multistep syntheses and difficult purification, non‐fullerene ETMs, such as rylene‐based organic small molecules, naphthalene diimide (NDI)‐based polymers and small molecules, and coronene diimide and indacenodithiophene small molecules, are also studied for PVSCs. Among these non‐fullerene ETMs, perylene diimide (PDI)‐based ETMs have attracted much attention, owing to their high electron nucleophilic potential and strong electron‐receiving power . Benefiting from rigid, planar p‐skeletons that are conducive to ordered molecular packing, PDI is a popular skeleton unit of liquid crystal molecules.…”

“…Among hole-transporting materials( HTMs) for PVSCs, poly(3-hexylthiophene) (P3HT) gives the devices the highest stability and reproducibility.T herefore, PVSCs with the structure of indium tin oxide (ITO)/ETM/perovskite/P3HT/ their high electron nucleophilic potential and strong electronreceiving power. [44][45][46][47][48][49][50][51] Benefiting from rigid, planar p-skeletons that are conducive to ordered molecular packing, PDI is ap opular skeleton unit of liquid crystal molecules. This rich source of new ETMs for PVSCs needs to be exploited more widely.…”