Highly Flexible Aqueous Photovoltaic Elastomer Gels Derived from Sulfonated Block Ionomers

Abstract

molecule absorbs a photon and becomes oxidized, electrons in the photosensitizer jump from their ground state to an excited state. These electrons, injected into the conduction band of TiO 2 nanoparticles, fl ow through a load to the anode where they are reintroduced into the cell and chemically reduce the dye so that the dye can absorb another photon and repeat the process. While liquid electrolytes yield high effi ciencies, [ 18 ] such devices suffer from solvent leakage and evaporation. [ 19 ] For this reason, DSSC research has shifted to using quasi-solid electrolytes, [ 20 ] and recent efforts have established [21][22][23] that the effi ciency and stability of DSSC devices containing electrolyte gels can exceed the performance of their liquid counterparts. Burschka et al. [ 24 ] have reported that solid-state DSSCs can achieve an effi ciency of 15% through the use of a hybrid perovskite dye.Ongoing demands to produce environment friendly, inexpensive, and reliable OPVs have likewise promoted the development of aqueous DSSCs. Using 1-methyl-3-propylimidazolium iodine with up to 10 wt% water has enabled a conversion effi ciency of up to 4.2%. [ 25 ] Combining a gel and dye with an aqueous environment has guided Velev and co-workers [ 26,27 ] to adopt a biomimetic approach by which to design OPVs on the basis of leaves. In this spirit, they have introduced the concept of hydrogel photovoltaic (HGPV) devices composed of an agarose gel containing 98 wt% water and exhibiting fi ll factor (FF) values up to 0.37 (the FF is a measure of the maximum power of a solar cell). Complementary FF values measured from biophotovoltaic HGPVs, inspired by the sequential charge-separation Z-scheme responsible for photosynthesis, have been recently reported by Schuhmann and co-workers [ 28,29 ] to range from 0.13 to 0.56. While the physical networks formed by natural gelling agents in HGPVs are stable, they are nonetheless mechanically fragile. Tough hydrogels substituted for this purpose tend to rely on chemical cross-linking and suffer from aging over time. To expand this biomimetic design with a physically cross-linkable macromolecule that exhibits excellent mechanical and stability attributes, we have chosen to fabricate HGPVs from self-organized multiblock copolymers, [ 30 ] each with a charged and thus hydrophilic midblock. These sulfonated block ionomers (SBIs), previously used in highly responsive ionic polymer-metal composites, [ 31 ] behave as thermoplastic elastomers (TPEs). For this reason and to retain consistency with the terminology we proposed earlier [ 32,33 ] for midblock-solvated TPE gels (as TPEGs), the resulting OPVs are hereafter referred to as photovoltaic elastomer gels (PVEGs).The PVEGs examined here are fabricated from poly[

Highly CO2-permeable membranes derived from a midblock-sulfonated multiblock polymer after submersion in water

“…This amphiphilic material, designated here as TESET to reflect its composition, is a poly[tert-butylstyrene-b-(ethylene-alt-propylene)-b-(styrene-r-styrenesulfonate)-b-(ethylene-alt-propylene)-b-tert-butylstyrene] pentablock polymer, the chemical structure of which is depicted in Scheme 1. This charged block polymer, originally designed to facilitate water transport in applications such as air conditioning, breathable fabrics, and filtration 16 , is equally suitable for diverse uses ranging from water purification 17,18 and pervaporation 19 to electroactive media 20 , antimicrobial surfaces 21 and organic photovoltaics 22 , in addition to gas separation. As a consequence of thermodynamic incompatibility between the blocks, the TESET macromolecule is subject to spontaneous microphase separation, selforganizing into a nanoscale morphology in similar fashion as neutral block copolymers 23,24 .…”

Ordering and Grain Growth in Charged Block Copolymer Bulk Films: A Comparison of Solvent‐Related Processes

“…Block ionomers (BIs), charged block copolymers possessing at least one block with ionic moieties, combine the ability of BCs to microphase order with the hydrophilic/ionophilic nature of polyelectrolytes and are therefore of interest in fuel cells and water purification . In addition, they have been utilized as electroactive media, amphoteric gas‐separation membranes, and organic photovoltaics . Unlike their BC analogs, BIs suffer from a significant complication–the formation of ionic clusters, which often trap nonequilibrium morphologies.…”

Solvent‐Templated Block Ionomers for Base‐ and Acid‐Gas Separations: Effect of Humidity on Ammonia and Carbon Dioxide Permeation

“…Recent efforts have introduced charged TPEs wherein a midblock is partially sulfonated. Technological interest in such sulfonated block ionomers (SBIs) ranges from fuel cells and proton‐exchange membranes to water‐desalination membranes, electroactive media, and organic photovoltaics, as well as molecular transport . While morphological development in nonionic block copolymers is well understood and largely controllable, a longstanding challenge of charged block copolymers in general has been kinetic entrapment due to the presence of ionic clusters that serve as additional physical crosslinks and thwart morphological equilibration .…”