Novel in situ crosslinked polymer electrolyte for solid-state dye-sensitized solar cells

A novel poly(citric acid-ethylene glycol)/LiI/I₂ (PCE/LiI/I₂) solid polymer electrolyte (SPE) based on the biodegradable PCE matrix has been prepared in situ, by penetrating of the PCE prepolymer sol into mesoporous TiO₂ photoanode, followed by curing. The PCE prepolymer can easily penetrate into the mesoporous photoanode, which could induce good interfacial contact between the SPE and photoanode. Assembled with the SPE, highly efficient and stable solid-state dye-sensitized solar cells (DSSCs) have been gained due to the good interfacial contact of SPE/TiO₂ photoanode as well as the favorable ionic conductivity of the SPE. The results show that the contents of CA determine the aggregation structure such as the inter-segmental distance and free volume of the PCE matrix, which consequently affects the ionic diffusion coefficient and conductivity of the PCE/LiI/I₂ electrolyte, and accordingly the photoelectric performance of the DSSCs. With CA content of 32.4 wt%, the SPE reaches the optimal ionic conductivity of 5.43 × 10^?5 S cm^?1 and the solid-state DSSCs obtain the best overall photoelectric conversion efficiency of 1.22 % at 60 mW cm^?2.     

Improved power conversion efficiency of dye-sensitized solar cells using side chain liquid crystal polymer embedded in polymer electrolytes

Side chain liquid crystal polymer (SCLCP) embedded in poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP)-based polymer electrolytes (PVdF-co-HFP:side chain liquid crystal polymer (SCLCP)) was prepared for dye-sensitized solar cell (DSSC) application. The polymer electrolytes contained tetrabutylammonium iodide (TBAI), iodine (I₂), and 8 wt% PVdF-co-HFP in acetonitrile. DSSCs comprised of PVdF-co-HFP:SCLCP-based polymer electrolytes displayed enhanced redox couple reduction and reduced charge recombination in comparison to those of the conventional PVdF-co-HFP-based polymer electrolyte. The significantly increased short-circuit current density (J_sc, 10.75 mA cm⁻²) of the DSSCs with PVdF-co-HFP:SCLCP-based polymer electrolytes afforded a high power conversion efficiency (PCE) of 5.32% and a fill factor (FF) of 0.64 under standard light intensity of 100 mW cm⁻² irradiation of AM 1.5 sunlight.     

Novel ionic iodide-siloxane hybrid electrolyte for dye-sensitized solar cells

A novel ionic siloxane hybrid electrolyte was fabricated by thermal polymerization of iodide-oligosiloxane resin. The nanosized iodide-oligosiloxane was synthesized by a simple sol-gel condensation of 3-iodopropyltrimethoxysilane and diphenylsilanediol. It is found that the composition and concentration of the oligosiloxane used in the electrolyte affect the performance of the dye-sensitized solar cells (DSSCs). An optimized DSSC with the hybrid electrolyte using smaller molecular-sized oligosiloxane with a greater amount of iodide groups presented solar to electricity conversion efficiency of 5.2% at 1 sunlight (100 mW cm(-2)), which is comparable to that afforded by a liquid electrolyte.     

Enhancement of ionic conductivity of PEO based polymer electrolyte by the addition of nanosize ceramic powders

The ionic conductivity of polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) has been improved by the addition of nanosize ceramic powders (TiO2 and AL2O3). The PEO based solid polymer electrolytes were prepared by the solution-casting method. Electrochemical measurement shows that the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte has the best ionic conductivity (about 10(-4) S cm(-1) at 40-60 degrees C). The lithium transference number of the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte was measured to be 0.47, which is much higher than that of bare PEO polymer electrolyte. Ac impedance testing shows that the interface resistance of ceramic-added PEO polymer electrolyte is stable. Linear sweep voltammetry measurement shows that the PEO polymer electrolytes are electrochemically stable in the voltage range of 2.0-5.0 V versus a Li/Li+ reference electrode.     

Controlled dissolution of polystyrene nanobeads: transition from liquid electrolyte to gel electrolyte

The widespread commercialization of dye-sensitized solar cells (DSSCs) remains limited because of the use of highly volatile liquid electrolytes. Recently, gel-type quasi-solid electrolytes containing a polymer additive or inorganic nanomaterial have shown promising results in terms of the cell efficiency. However, most gel electrolytes have serious obstacles for pore-filling because of their high viscosity. Herein, we report the first observation of the transition from a liquid to a gel electrolyte after filling the cell with the liquid electrolyte using the controlled dissolution of polystyrene nanobeads on the counter electrode, suggesting that the pore-filling problem can be diminished in quasi-solid state DSSCs. The time-resolved solidification allows for the preparation of the gel electrolyte without interfering with the cell performance. The optimal DSSC composed of the gel electrolyte exhibits almost the same power conversion efficiency as the liquid electrolyte based DSSC when measured using an AM1.5G solar simulator at 100 mW/cm(2) light illumination. Moreover, the long-term stability of the DSSC was greatly improved.     

染料敏化太阳能电池中凝胶电解质的研究

为提高染料敏化太阳能电-池中电解液的稳定性,对凝胶电解质进行了研究.以1,2-二1甲基-3-丙基咪唑碘(DMPII)作为Ⅰ-源,以3甲氧基丙腈作为溶剂,以偏四氟乙烯一六氟丙烯聚合物(P(VDF-HFP))作为胶凝剂,N-甲基苯并咪唑作为添加剂,制备了凝胶电解质.结果表明,随着电解质中DMPII量及碘量的增加,染料敏化太...     

Synthesis and characterization of new dithienosilole-based copolymers for polymer solar cells

A series of dithienosilole-based copolymers, poly [(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-5,5'-diyl] (P1), poly[(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,2'-bithiazole)-5,5'-diyl] (P2), poly[(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2, 6-diyl-alt-(10 -methyl-phenothiazine)-3,7-diyl](P3), poly[(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-9,10-anthracene)-5,5'-diyl] (P4) were synthesized by the Pd-catalyzed Stille polymerization method. Electron-deficient benzothiadiazole and bithiazole units and electron-rich phenothiazine and anthracene moieties were incorporated into the polymer backbone to obtain the broad absorption spectrum and to improve the hole-transporting characteristics, respectively. The polymer solar cell (PSC) was fabricated with a layered structure of ITO/PEDOT:PSS/polymer:C71-PCBM (1:3)/LiF/Al. The best performance of PSC was obtained at P3:C71-PCBM which reaches a power conversion efficiency (PCE) of 1.18%, with a short circuit current density (J(sc)) of 4.75 mA/cm2, an open circuit voltage (V(oc)) of 0.71 V, and a fill factor (FF) of 0.35 under AM 1.5G irradiation (100 mW/cm2).     

End-functional silicone coupling agent modified PEO/P(VDF-HFP)/SiO(2) nanocomposite polymer electrolyte DSSC

The end-functional silicone coupling agent (dodecyl-trimethoxysilane, DTMS for short) was used to modify the PEO/P(VDF-HFP)/SiO(2) nanocomposite polymer electrolyte (CPE) and the different amounts of DTMS modification effects were studied. The experiments showed the silicone coupling agent with hydrophobic alkyl chains (-C(12)H(25)) chemically engineered on the SiO(2) nanoparticles, and formed a Si-O-Si cross-linked network in the new nanocomposite polymer electrolyte. Proper content of DTMS modified CPE exhibited improved ionic conductivity and the connection with the photoanode and counter electrode. However, much higher content of the DTMS modification changed the conformation of the polymer network and reduced the ionic movement. Compared with the performance (3.84%) of the original DSSC, the DSSC with functional silicone coupling agent modified CPE (DTMS:SiO(2) = 2:1, mol ratio) exhibited improved J(sc) (7.94?mA?cm(-2)), V(oc) (0.624?V) and optimal efficiency (5.2%) (measured at AM1.5, light intensity of 58.4?mW?cm(-2)). The V(oc) of the silicone coupling agent modified polymer electrolyte DSSC is obviously improved, which is mainly due to that the hydrophobic alkyl chain end groups formed an insulating layer that retarded the electron recombination at the TiO(2) nanoporous photoanode/polymer electrolyte interface. The DTMS:SiO(2) = 2:1 modified CPE type DSSC exhibited a performance of 6.42% at a light intensity of 32.1?mW?cm(-2) and 4.94% at 99.2?mW?cm(-2).     

High-efficiency, solid-state, dye-sensitized solar cells using hierarchically structured TiO₂ nanofibers

High-performance, room-temperature (RT), solid-state dye-sensitized solar cells (DSSCs) were fabricated using hierarchically structured TiO? nanofiber (HS-NF) electrodes and plastic crystal (PC)-based solid-state electrolytes. The electrospun HS-NF photoelectrodes possessed a unique morphology in which submicrometer-scale core fibers are interconnected and the nanorods are dendrited onto the fibers. This nanorod-in-nanofiber morphology yielded porosity at both the mesopore and macropore level. The macropores, steming from the interfiber space, afforded high pore volumes to facilitate the infiltration of the PC electrolytes, whereas the mesoporous nanorod dendrites offered high surface area for enhanced dye loading. The solid-state DSSCs using HS-NFs (DSSC-NF) demonstrated improved power conversion efficiency (PCE) compared to conventional TiO? nanoparticle (NP) based DSSCs (DSSC-NP). The improved performance (>2-fold) of the DSSC-NFs was due to the reduced internal series resistance (R(s)) and the enhanced charge recombination lifetime (τ(r)) determined by electrochemical impedance spectroscopy and intensity modulated photocurrent/photovoltage spectroscopy. The easy penetration of the PC electrolytes into HS-NF layers via the macropores reduces R(s) significantly, improving the fill factor (FF) of the resulting DSSC-NFs. The τ(r) difference between the DSSC-NF and DSSC-NP in the PC electrolytes was extraordinary (~14 times) compared to reported results in conventional organic liquid electrolytes. The optimized PCE of DSSC-NF using the PC electrolytes was 6.54, 7.69, and 7.93% at the light intensity of 100, 50, and 30 mW cm?2, respectively, with increased charge collection efficiency (>40%). This is the best performing RT solid-state DSSC using a PC electrolyte. Considering the fact that most reported quasi-solid state or nonvolatile electrolytes require higher iodine contents for efficient ion transport, our HS-NFs are a promising morphology for such electrolytes that have limited ion mass transport.     

Organic photovoltaic devices based on an acceptor of solution-processable functionalized graphene

We prepared the exfoliation of graphite, which was necessary for the production of graphene sheets that are desirable for the fabrication of nano-composites. Then a Solution-Processable Functionalized Graphene (SPFGraphene) with functionalization groups doped with P3HT hybrid thin film-based organic photovoltaic cells (OPVCs) was systematically identified using a general device structure of, ITO/PEDOT:PSS/P3HT:SPFGraphene/LiF/Al. The effect of annealing on the photoelectric properties of the SPFGraphene was analyzed by Fourier transform infrared FT-IR spectroscopy and solar cell performance. After treatment at different annealing temperatures, with an increase in the SPFGraphene content, the short-circuit current density J(SC) and power conversion efficiency PCE of the hybrid devices increased first, reaching the peak efficiency for the 10 wt% SPFGraphene content, and then decreased. After annealing at 160 degrees C, the device containing 10 wt% SPFGraphene showed the open-circuit voltage V(OC) of 0.73 V, the J(SC) value of 3.98 mA cm(-2), fill factor (FF) value of 0.36, the PCE value of 1.046%. After thermal annealing at 210 degrees C, with the removal of the functional groups and recovery of the pi-conjugated areas, the conductivity of the graphene sheet and the charge carrier-transport mobility increased greatly, the J(SC) value of the 10 wt% SPFGraphene content device increased to 4.2 mA cm(-2), the V(OC) value decreased to 0.59 V, which may be attributed to the altered work-function value of the functionalized graphene and low quasi-Fermi levels for electrons and holes, the FF value was 0.27, and the PCE was 0.669%, which is lower than the former one. The results indicated that annealing at the appropriate temperature can improve the device performance greatly, and the functionalized graphene is expected to be a competitive candidate in organic photovoltaic applications because it is soluble, cheap, easily prepared, stable, and inert against the ambient conditions.     

Novel photoactive fluorene-based terpolymers incorporating carbazole for photovoltaic application

A series of novel photoactive conjugated terpolymers based on N-alkyl carbazole, 9,9-didecylfluorene, and bis(thienyl)benzothiadiazole were synthesized by the Pd-catalyzed Suzuki polymerization method with various molar ratios of the carbazole derivatives. Electron-deficient benzothiadiazole and electron-rich carbazole moieties were incorporated into the polymer backbone to obtain the broad absorption spectrum and to improve the hole-transporting characteristics, respectively. The polymer solar cell (PSC) was fabricated with a layered structure of ITO/PEDOT: PSS/polymer:C71-PCBM (1:3)/LiF/Al. The best performance of PSC was obtained at P1:C71-PCBM whose reaches a power conversion efficiency (PCE) of 2.62%, with a short circuit current density (J(SC)) of 8.61 mA/cm2, an open circuit voltage (V(OC)) of 0.82 V, and a fill factor (FF) of 0.37 under AM 1.5 G irradiation (100 mW/cm2).     

Enhancement of photocurrent of dye-sensitized solar cell by composite liquid electrolyte including NiO nanosheets

A novel composite electrolyte incorporating inorganic NiO nanosheets into iodide/triiodide liquid electrolyte containing 4-tert-butylpyridine (TBP) for dye-sensitized solar cells (DSCs) was reported herein for the first time. The hydrothermally prepared NiO nanosheets showed a high aspect ratio, confirmed by field emission scanning electron microscopy (FESEM). DSCs assembled with such nanosheet-based composite electrolytes showed more than 15% increased photocurrent, and hence significantly promoted light-to-energy conversion efficiency relative to reference one. The enhancement of photocurrent is primarily due to the light-scattering effect which is brought by the incorporating of inorganic nanosheets. Also, electrochemical impedance spectroscopy (EIS) was employed to investigate the charge-transfer kinetics at the interface between the counter electrode and the composite electrolyte of DSCs. The symmetrical cells (TCO/Pt/electrolyte/Pt/TCO) assembled with such nanosheet-based composite electrolyte showed a decreased charge-transfer resistance (R(ct)). The optimum DSC including NiO nanosheets showed a short-circuit current of 14.01 mA/cm2, an open-circuit voltage of 0.73 V, a fill factor of 0.54, and an overall conversion efficiency of 5.44% at 100 mW/cm2.     

Graphene supported platinum nanoparticle counter-electrode for enhanced performance of dye-sensitized solar cells

Composites of few layered graphene (G) and platinum (Pt) nanoparticles (NP) with different loadings of Pt were used as counter electrode (CE) in dye-sensitized solar cell (DSSC). NPs were deposited directly on to G using pulsed laser ablation method (PLD). DSSCs formed using the composite CEs show improved performance compared to conventional Pt thin film electrode (Std Pt) and unsupported Pt NPs. Composite with 27% loading of Pt shows 45% higher efficiency (η = 2.9%), greater short circuit current (J(sc) = 6.67 mA cm(-2)), and open circuit voltage (V(oc) = 0.74 V) without any loss of the fill factor (FF = 58%) as compared to the cells fabricated using Std Pt electrodes. Values of η, J(sc) and V(oc) for DSSC using Std Pt CE were 2%, 5.05 mA cm(-2) and 0.68 V, respectively. Electrochemical impedance spectroscopy using I(-)(3)/I(-) redox couple confirm lower values of charge transfer resistance for the composite electrodes, e.g., 2.36 Ω cm(2) as opposed to 7.73 Ω cm(2) of Std Pt. The better catalytic activity of these composite materials is also reflected in the stronger I(-)(3) reduction peaks in cyclic voltammetry scans.     

Performance characteristics of guanine incorporated PVDF-HFP/PEO polymer blend electrolytes with binary iodide salts for dye-sensitized solar cells

In this work, we have investigated the influence of guanine as an organic dopant in dye-sensitized solar cell (DSSC) based on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) polymer blend electrolyte along with binary iodide salts (potassium iodide (KI) and tetrabutylammonium iodide (TBAI)) and iodine (I₂). The PVDF-HFP/KI + TBAI/I₂, PVDF-HFP/PEO/KI + TBAI/I₂ and guanine incorporated PVDF-HFP/PEO/KI + TBAI/I₂ electrolytes were prepared by solution casting technique using DMF as solvent. The PVDF-HFP/KI + TBAI/I₂ electrolyte showed an ionic conductivity value of 9.99 × 10⁻⁵ Scm⁻¹, whereas, it was found to be increased to 4.53 × 10⁻⁵ Scm⁻¹ when PEO was blended with PVDF-HFP/KI + TBAI/I₂ electrolyte. However, a maximum ionic conductivity value of 3.67 × 10⁻⁴ Scm⁻¹ was obtained for guanine incorporated PVDF-HFP/PEO/KI + TBAI/I₂ blend electrolyte. The photovoltaic properties of all these polymer electrolytes in DSSCs were characterized. As a consequence, the power conversion efficiency of the guanine incorporated PVDF-HFP/PEO/KI + TBAI/I₂ electrolyte based DSSC was significantly improved to 4.98% compared with PVDF-HFP/PEO/KI + TBAI/I₂ electrolyte based DSSC (2.46%). These results revealed that the guanine can be an effective organic dopant to enhance the performance of DSSCs.     

具有2D-EDAPbI4薄覆盖层的环境稳定的FAPbI3基钙钛矿太阳能电池（英文）

二维(2D)卤化铅钙钛矿材料是钙钛矿太阳能电池(PSC)中最有前途的吸光材料之一,具有优异的稳定性和缺陷钝化作用.然而,这些稳定的二维PSC的转换效率仍远远落后于三维钙钛矿电池.在本文中我们通过原位生长的方法将2D EDAPbI4层成功制备在3D FAPbI3层表面。这种合理设计的2D-3D钙钛矿薄膜分层结构可以明显提高电池的效率.另外,由于EDAPbI4层的高抗湿性和抑制迁移, 2D-3D电池器件显示出明显增强的长期稳定性,在200 h内一直保持初始转换效率,甚至在500 h后仍能保持其初始转化效率的90%.     

End-group functionalization of poly(3-hexylthiophene) as an efficient route to photosensitize nanocrystalline TiO2 films for photovoltaic applications

Bulk heterojunction (BHJ) and dye-sensitized solar cells (DSSCs) have seen increased popularity over recent years and each technology has experienced tremendous improvements in power conversion efficiencies (PCEs), reaching 8 and 12%, respectively. The two technologies have been on independent improvement pathways, and this work establishes a link between them by using the archetypical hole conductor (poly-3-hexylthiophene, P3HT) in BHJs as a sensitizer on TiO(2) for DSSC applications. Three polymers were synthesized and examined as potential TiO(2) sensitizers in DSSCs under AM1.5 solar radiation. Using Grignard metathesis, regioregular P3HT was synthesized then functionalized with either one or two cyanoacrylic acid linker moieties to bind to the TiO(2) surface. End-group modification resulted in minimal changes to the optical and electronic properties as compared to pristine P3HT. Cyclic voltammetry (CV) experiments at anodic potentials of adsorbed sensitizer quantified the amount of alkylthiophene adsorbed on the TiO(2), whereas under reductive sweeps, cyanoacrylic acid end-group binding was determined. CVs of each polymer indicated that loading was drastically different as compared to pristine P3HT with the lowest loading on TiO(2) and monofunctionalized P3HT exhibited the highest loading. The DSSCs showed power conversion efficiencies (PCEs) of 0.1%, 0.2 and 2.2% for the polymer-sensitized TiO(2) of the unfunctionalized, monofunctionalized and difunctionalized polymers, respectively. DSSCs were then subjected to electrochemical impedance spectroscopy (EIS) in the dark and under monochromatic light radiation. The large variance in performance for the functionalized-P3HT sensitizers is attributed to differences in the adsorption modes of sensitizer on the TiO(2) surface, which in the difunctionalized case limits electrolyte recombination and favors forward charge transfer reactions.     

Synthesis and optimization of P(MMA-BA-MAA)/PEG-based polymer gel electrolytes

A polymer gel electrolyte based on poly(methyl methacrylate-butyl acrylate-methacrylic acid)/polyethylene glycol 400 blend (P(MMA-BA-MAA)/PEG400) was successfully prepared by a simple and efficient procedure. The optimal ionic conductivity was achieved to be 3.12 mS cm^?1 at the temperature of 30 °C when the electrolyte has the composition of 20 wt% P(MMA-BA-MAA)/PEG400 blend, 0.6 M NaI, and 0.06 M I₂ in the solvent γ-butyrolactone (GBL). For tuning the ionic conductivity, various additives were introduced into the polymer gel electrolytes. The measured values of open circuit voltage, short circuit current, and total photovoltaic efficiency indicates that the adding of pyridine (PY) leads to better performance of the final dye-sensitized solar cells (DSSCs), while the adding of Guanidine thiocyante (GuSCN) leads to a worse one. 4-Tert-butylpyridine (TBP) additive takes a more complex effect on the performance of the final DSSCs. For polymer gel electrolyte with 0.5 M pyridine, the final fabricated dye-sensitized solar cell has overall energy conversion efficiency (η) of 3.63 % (0.16 cm² active area) under AM 1.5 at irradiation of 100 mW cm^?2, which reached the level of the liquid electrolyte based device (η = 3.83 % at 0.16 cm² active area). Meanwhile, this gel electrolyte exhibits well long-term stability. The mechanism analysis revealed the dependences of ionic conductivity on the concentration of polymer and NaI and the temperatures.     

Enhancement of photovoltaic performance in dye-sensitized solar cells with the spin-coated TiO2 blocking layer

The TiO2 thin film layers were introduced with the spin-coating method between FTO electrode and TiO2 photoanode in dye sensitized solar cell (DSSC) to prevent electron back migration from the FTO electrode to electrolyte. The DSSC containg different thickness of TiO2 thin film (10-30, 40-60 and 120-150 nm) were prepared and photovoltaic performances were analysed with /-Vcurves and electrochemical impedance spectroscopy. The maximum cell performance was observed in DSSC with 10-30 nm of TiO2 thin film thickness (11.92 mA/cm2, 0.74 V, 64%, and 5.62%) to compare with that of pristine DSSC (11.09 mA/cm2, 0.65 V, 62%, and 4.43%). The variation of photoelectric conversion efficiency of the DSSCs with different TiO2 thin film thickness was discussed with the analysis of crystallographic and microstructural properties of TiO2 thin films.     

The remediation performance of a specific electrokinetics integrated with zero-valent metals for perchloroethylene contaminated soils

This research was conducted to evaluate an integrated technique, combination of the electrokinetics (EK) and zero-valent metal (ZVM), for remediation of the perchloroethylene (PCE) contaminated soils. Various experimental conditions were controlled such as different voltage gradients, the position of ZVM, and ZVM species. The appropriate operational parameters are concluded as follows: (1) 0.01 M sodium carbonate serves as the working solution; (2) the voltage gradient is controlled at 1.0 V/cm; (3) ZVM wall is settled close to the anode. Based on the above operation conditions, the pH value of working solution can maintain at neutral range for avoiding the soil acidification. Neutral pH also causes the system to stay at a stable status of electricity consumption. The removal efficiency reaches 99% and 90% for decontaminating the PCE in the pore-water and the soil, respectively, after a 10-day treatment. The zero-valent zinc performs better PCE degradation than zero-valent iron. Moreover, the soils treated by EK+ZVM still possess their original properties.