Open-circuit voltage enhancement on the basis of polymer gel electrolyte for a highly stable dye-sensitized solar cell

Bacteriorhodopsin Enhances Efficiency of Perovskite Solar Cells

Recently, halide perovskites have upstaged decades of solar cell development by reaching power conversion efficiencies that surpass the performance of polycrystalline silicon. The efficiency improvement in the perovskite cells is related to repeated recycling between photons and electron-hole pairs, reduced recombination losses, and increased carrier lifetimes. Here, we demonstrate a novel approach toward augmenting the perovskite solar cell efficiency by invoking the Förster Resonance Energy Transfer (FRET) mechanism. FRET occurs in the near-field region as the bacteriorhodopsin (bR) protein, and perovskite has similar optical gaps. Titanium dioxide functionalized with the bR protein is shown to accelerate the electron injection from excitons produced in the perovskite layer. FRET predicts the strength of long-range excitonic transport between the perovskite and bR layers. Solar cells incorporating TiO₂/bR layers are found to exhibit much higher photovoltaic performance as compared to baseline cells without bR. These results open the opportunity to develop a new class of bioperovskite solar cells with improved performance and stability.

Carbon nanoparticle template assisted formation of mesoporous TiO2 photoanodes for quantum dot-sensitized solar cells

While the power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs) is still far below their theoretical efficiency, we herein provide a method to improve the solar cell performance by using carbon nanoparticles as a template to construct TiO₂ mesoporous photoanodes.

Effects of TiO2 and TiC Nanofillers on the Performance of Dye Sensitized Solar Cells Based on the Polymer Gel Electrolyte of a Cobalt Redox System

Polymer gel electrolytes (PGEs) of cobalt redox system are prepared for dye sensitized solar cell (DSSC) applications. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is used as a gelator of an acetonitrile (ACN) liquid electrolyte containing tris(2,2'-bipyridine)cobalt(II/III) redox couple. Titanium dioxide (TiO2) and titanium carbide (TiC) nanoparticles are utilized as nanofillers (NFs) of this PGE, and the effects of the two NFs on the conductivity of the PGEs, charge-transfer resistances at the electrode/PGE interface, and the performance of the gel-state DSSCs are studied and compared. The results show that the presence of TiC NFs significantly increases the conductivity of the PGE and decreases the charge-transfer resistance at the Pt counter-electrode (CE)/PGE interface. Therefore, the gel-state DSSC utilizing TiC NFs can achieve a conversion efficiency (6.29%) comparable to its liquid counterpart (6.30%), and, furthermore, the cell efficiency can retain 94% of its initial value after a 1000 h stability test at 50 °C. On the contrary, introduction of TiO2 NFs in the PGE causes a decrease of cell performances. It shows that the presence of TiO2 NFs increases the charge-transfer resistance at the Pt CE/PGE interface, induces the charge recombination at the photoanode/PGE interface, and, furthermore, causes a dye desorption in a long-term-stability test. These results are different from those reported for the iodide redox system and are ascribed to a specific attractive interaction between TiO2 and cobalt redox ions.

In Situ Gelation of Poly(vinylidene fluoride) Nanospheres for Dye-Sensitized Solar Cells: The Analysis on the Efficiency Enhancement upon Gelation

The in situ gelation that utilizes the dissolution of polymers inside the cell is allowed high concentration polymer gel without concerns regarding high viscous electrolyte incorporation into the cell as in the conventional approach. We demonstrate the in situ gelation of polymer composite electrolytes using poly(vinylidene fluoride) nanospheres (PVdF NSs). The PVdF NSs were synthesized by high pressure emulsion polymerization using gaseous vinylidene fluoride monomers. Compared to the liquid electrolyte (LE) DSCs without PVdF gelation, the PVdF polymer gel electrolyte (PGE) DSCs displayed higher η than the LE DSCs; specifically, the 10 wt % PVdF PGE DSCs display 8.1% of the η, while the LE DSCs only display 6.5%. We characterized the effect of PVdF PGE on the photovoltaic parameters in detail. We also compared the long-term stability of DSCs containing LE and PVdF PGE. The DSCs with PVdF PGE exhibited high stability compared to the LE DSCs, similar to a conventional PGE system. We believe that this facile in situ gelation approach could be utilized for not only the practical application of polymer gel electrolytes DSCs but also for various energy-storage devices.

Efficient quasi-solid state dye sensitized solar cell using succinonitrile : thiourea based electrolyte composition

SEM micrograph of the optimized electrolyte with SCN : TU. Inset shows the current density–voltage characteristics of the DSSCs with reference and optimized electrolytes, A1 and A2, respectively.

Dispelling clichés at the nanoscale: the true effect of polymer electrolytes on the performance of dye-sensitized solar cells

In the field of dye-sensitized solar cells, polymer electrolytes are among the most studied materials due to their ability to ensure both high efficiency and stability, the latter being a critical point of these devices. Hundreds of polymeric matrices have been proposed over the years, and their functionalization with several groups, the variation of their molecular weight and the tuning of the crosslinking degree have been investigated. However, the true effect that polymeric matrices have on the cell parameters has often been addressed superficially, and hundreds of papers justify the obtained results with a simple bibliographic reference to other systems (sometimes completely different). This work proposes a system of nanoscale growth and crosslinking of a polymer electrolyte inside a nanostructured photoanode. Electrochemical and photovoltaic parameters are carefully monitored as a function of thickness and degree of penetration of the electrolyte. The results derived from this study refute many clichés generally accepted and taken for granted in many literature articles, and – for the first time – a compromise between the amount of polymer, cell efficiency and stability is achieved.

Poly(ionic liquid)/ionic liquid/graphene oxide composite quasi solid-state electrolytes for dye sensitized solar cells

A composite gel electrolytes containing poly(1-butyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide), 1-propyl-3-methylimidazolium iodide and graphene oxide are prepared for dye-sensitized solar cells, without any volatile organic solvent.

An efficient quasi solid state dye sensitized solar cell based on polyethylene glycol/graphene nanosheet gel electrolytes

A poly(ethylene glycol)/graphene nanosheet quasi solid gel electrolyte was synthesized using an in situ polymerization technique for dye-sensitized solar cells (DSSCs).

Functional quasi-solid-state electrolytes for dye sensitized solar cells prepared by amine alkylation reactions

Novel quasi-solid state electrolytes for dye-sensitized solar cells (QSS-DSCs) are prepared by the amine alkylation reaction.

Layered double hydroxides as an effective additive in polymer gelled electrolyte based dye-sensitized solar cells

Layered double hydroxides (LDH), a class of anionic clay materials, were developed as an effective additive for polymer gelled electrolytes for use in dye-sensitized solar cells (DSSC). Carbonate and chloride intercalated Zn-Al LDHs, ZnAl-CO3 LDH, and ZnAl-Cl LDH were prepared with coprecipitation methods. The addition of the two LDHs significantly improved, in terms of power conversion efficiency (PCE), over the plain poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) gelled electrolyte and competed favorably with the liquid electrolyte based DSSCs, 8.13% for the liquid electrolyte, 7.48% for the plain PVDF-HFP gelled electrolyte, 8.11% for the ZnAl-CO3 LDH/PVDF-HFP gelled electrolyte, and 8.00% for the ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The good performance in PCEs achieved by the LDH-loaded DSSCs came mainly from the significant boost in open circuit voltages (Voc), from 0.74 V for both the liquid electrolyte and PVDF-HFP gelled electrolyte based DSSCs to 0.79 V for both the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The boost in Voc was contributed mainly by the positive shift in redox potential of the redox couple, I(-)/I3(-), as revealed from cyclic voltammetry analyses. As for the long-term stability, PCE retention rates of 96 and 99% after 504 h were achieved by the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs, respectively, appreciably better than 92% achieved by the liquid electrolyte based one after 480 h.

Supramolecular ionic liquid gels for quasi-solid-state dye-sensitized solar cells

A 1-propyl-3-methylimidazolium iodide based supramolecular ionic liquid gel was prepared through the host-guest interactions between a host of β-cyclodextrin and a room temperature ionic liquid type guest, 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide, which contains bis(trifluoromethylsulfonyl)imide as the guest group. The gel-to-sol phase transition temperature of the prepared supramolecular ionic liquid gel could be tuned by the ratio of host to guest. The synthesized supramolecular ionic liquid gel was further applied in quasi-solid-state electrolyte dye-sensitized solar cells, which showed a power conversion efficiency of 4.79% under the simulated air mass 1.5 solar spectrum illumination at 100 mW cm(-2) and excellent long-term stability.