4 research outputs found
Humic Acid as a Sensitizer in Highly Stable Dye Solar Cells: Energy from an Abundant Natural Polymer Soil Component
Humic acid (HA), a natural polymer
and soil component, was explored
as a photosensitizer in dye-sensitized solar cells (DSSCs). Photophysical
and electrochemical properties show that HA covers a broad visible
range of the electromagnetic spectrum and exhibits a quasi-reversible
nature in cyclic voltammetry (CV). Because of its abundant functionalities,
HA was able to bind onto the nano-titania surface and possessed good
thermal stability. HA was employed as a sensitizer in DSSCs and characterized
by various photovoltaic techniques such as <i>I</i>–<i>V</i>, incident-photo-to-current conversion efficiency (IPCE),
electrochemical impedance spectroscopy (EIS), and Tafel polarization.
The HA-based device shows a power conversion efficiency (PCE) of 1.4%
under 1 sun illumination. The device performance was enhanced when
a coadsorbent, chenodeoxycholic acid (CDCA), along with HA was used
and displayed 2.4% PCE under 0.5 sun illumination. The DSSCs employing
HA with CDCA showed excellent stability up to 1000 h. The reported
efficiency of devices with HA is better than that of devices with
all natural sensitizers reported so far
Anisotropic One-Dimensional Aqueous Polymer Gel Electrolyte for Photoelectrochemical Devices: Improvement in Hydrophobic TiO<sub>2</sub>–Dye/Electrolyte Interface
Aqueous
photoelectrochemical devices have emerged recently as promising area
because of their economic and ecological friendliness. In the present
work, we have expedited surface active amphiphilic quasi-solid aqueous
polymer gel electrolyte (PGE) with hydrophobic sensitizer SK3 in water-based
dye sensitized solar cell (DSSC). PGE was prepared from amphiphilic
block copolymer (PEO)–(PPO)–(PEO) with iodide–triiodide
couple in pure aqueous media without any organic solvent. This block
copolymer, with iodide-triiodide salt exhibits 1D-lamellar microcrystalline
phase which shows stability in the temperature range of 25–50
°C. Parallel (||<sup>al</sup>) and perpendicular (⊥<sup>ar</sup>) alignment of anisotropic lamellar microcrystalline phase
pertaining by PGE were characterized and applied in quasi-solid DSSC.
Temperature dependency of ionic conductivity, triiodide diffusion,
differential scanning calorimetry, viscosity, and 1-D lamellar anisotropic
behavior were studied. Surface active effect of PGE at the hydrophobic
dye sensitized photoanode was investigated and compared with liquid
water based electrolyte. Because of the amphiphilic nature and thermoreversible
sol–gel transition of PGE at a lower temperature (0 to −2
°C) allowing PGE to penetrate efficiently inside the hydrophobic
surface of dye–TiO<sub>2</sub> and resulted in a fused contact
between dye–TiO<sub>2</sub>/PGE interface. This aqueous PGE
successfully enhances the performance of DSSCs over liquid water based
devices by improving their <i>V</i><sub>oc</sub> and stability.
Under 0.5 sun illumination, DSSC with 1-D lamellar perpendicularly
align PGE shows an efficiency of 2.8% and stability up to 1000 h at
50 °C
Heteroleptic Coordination Polymer Electrolytes Initiated by Lewis-Acidic Eutectics for Solid Zinc–Metal Batteries
Solid polymer electrolytes (SPEs)
offer a viable path
for overcoming
the interfacial problems caused by side reactions and irregular deposition
in rechargeable Zn (zinc)–metal batteries. However, this potential
has been hampered by limited Zn2+ mobility in polymers;
a central conundrum remains on how to solvate Zn2+ strongly
enough to free it from anionic traps but weakly enough to minimize
its migration barriers. Inspired by biologically dynamic Zn functions,
we report a general strategy for constructing highly Zn2+-conductive SPEs by the engineering of heteroleptic coordination.
Leveraging polymerization catalyzed by Lewis-acidic Zn2+ predissociated eutectics, we stoichiometrically integrate polymeric
ligands (polyacrylamide) with kindred small-molecule co-ligands (acetamide)
for Zn2+ centers. This heteroleptic configuration allows
for the formation of entropy-increased ion channels with both labile
Zn2+–polymer bonding and accelerated polymer mobility,
warranting conductivity gains of 2 orders of magnitude and doubling
the Zn2+-transference number to 0.44, compared with traditional
SPEs. The applicability of the proposed heteroleptic coordination
design is also demonstrated by the improved reversibility of Zn plating/stripping
process (1200 h) and prolonged cycle life of solid Zn–metal
batteries (350 cycles with Mo6S8 cathodes) with
improved Coulombic efficiency (∼99%). This study underscores
the importance of tailoring the coordination environment in improving
cationic mobility in polymers
Heteroleptic Coordination Polymer Electrolytes Initiated by Lewis-Acidic Eutectics for Solid Zinc–Metal Batteries
Solid polymer electrolytes (SPEs)
offer a viable path
for overcoming
the interfacial problems caused by side reactions and irregular deposition
in rechargeable Zn (zinc)–metal batteries. However, this potential
has been hampered by limited Zn2+ mobility in polymers;
a central conundrum remains on how to solvate Zn2+ strongly
enough to free it from anionic traps but weakly enough to minimize
its migration barriers. Inspired by biologically dynamic Zn functions,
we report a general strategy for constructing highly Zn2+-conductive SPEs by the engineering of heteroleptic coordination.
Leveraging polymerization catalyzed by Lewis-acidic Zn2+ predissociated eutectics, we stoichiometrically integrate polymeric
ligands (polyacrylamide) with kindred small-molecule co-ligands (acetamide)
for Zn2+ centers. This heteroleptic configuration allows
for the formation of entropy-increased ion channels with both labile
Zn2+–polymer bonding and accelerated polymer mobility,
warranting conductivity gains of 2 orders of magnitude and doubling
the Zn2+-transference number to 0.44, compared with traditional
SPEs. The applicability of the proposed heteroleptic coordination
design is also demonstrated by the improved reversibility of Zn plating/stripping
process (1200 h) and prolonged cycle life of solid Zn–metal
batteries (350 cycles with Mo6S8 cathodes) with
improved Coulombic efficiency (∼99%). This study underscores
the importance of tailoring the coordination environment in improving
cationic mobility in polymers