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Structural engineering of the light-harvesting dyes employed in DSSCs (dye-sensitized solar cells) with a systematic choice of the electron-donating and -accepting groups as well as the π-bridge allows the (photo)physical properties of dyes to match the criteria needed for improving the DSSC efficiency. Herein, we report an effective approach of molecular engineering of DSSC sensitizers, aiming to gain insights on the configurational impact of the fluorenyl unit on the optoelectronic properties and photovoltaic performance of DSSCs. Five new organic dyes (GZ116, GZ126, GZ129, MA1116, and MA1118) with a D-A-π-A framework integrated with a fluorenyl moiety were designed and synthesized for DSSCs. The fluorenyl unit is configured as part of the π-spacer for the GZ series, whereas it connected on the electron-deficient quinoxaline motif for the MA series. The devices fabricated from the MA1116 sensitizer produced the best performance under standard AM 1.5 G solar conditions as well as dim-light (300-6000 lx) illumination. The devices fabricated from MA1116 displayed a PCE of 8.68% (Jsc = 15.00 mA cm-2, Voc = 0.82 V, and FF = 0.71) under 1 sun and 26.81% (Jsc = 0.93 mA cm-2, Voc = 0.68 V, and FF = 0.76) under 6000 lx illumination. The device efficiency based on dye MA1116 under 1 sun outperformed that based on the standard N719 dye, whereas a comparable performance between devices based on MA1116 and N719 was achieved under dim-light conditions. A combination of enhancing the charge separation, suppressing dye aggregation, and providing better insulation that prevents the oxidized redox mediator from approaching the TiO2 surface all contribute to the superior performance of DSSCs fabricated based on these light-harvesting dyes. The judicious integration of the fluorenyl unit in a D-A-π-A-based DSSC would be a promising strategy to boost the device performance.

Silicon (Si) on-chip metallization was carried out through surface functionalization and electroless deposition of copper (Cu). Surface functionalization of Si was performed by grafting an amine (N...

Cu(I)/(II) complex redox couples in dye-sensitized solar cell (DSSC) are of particular interest because of their low reorganization energy between Cu(I) and Cu(II), which minimizes the potential lo...

This work demonstrates a general and effective approach to activate inert polymer chains for further reactions through electrochemically driven radical generation and radical transfer reactions. The generated radical-containing polymer chains show capacity for further polymer reactions and preparation of polymer hybrids.

This paper reports a new approach to realize direct selective electroless deposition (ELD) without the requirement of photolithography. This method involves sequential silane-compound modifications in which the first modification creates a hydrophobic surface on the TiO2-coated glass using a fluorine-rich alkoxysilane compound, followed by a laser ablation to create the pattern. Then, the entire substrate is immersed into an aqueous solution containing amino-silane equipped Pd nanoparticles for the second modification. Because most substrate surface is hydrophobic, the amino-silane-equipped Pd catalysts can only graft on the laser-ablated zone to accomplish selective ELD.

In this study, we aim to develop an efficient, eco-friendly and cost-effective electrolyte solvent mixture for Dye-sensitized Solar Cells (DSCs) by using a deep eutectic solvent (DES). A high-purity choline chloride–phenol DES was synthesized and characterized by Fourier-transform infrared and nuclear magnetic resonance spectroscopy; thermogravimetric analysis and differential scanning calorimetry. The resulting product was mixed with acetonitrile, a typical volatile electrolyte solvent, at various ratios for use as electrolyte in DSCs. The photovoltaic parameters (Jsc, Voc, fill factor, efficiency) of these DSC devices were monitored to investigate their long-term performance. The performance of DES-added cells was initially less efficient, but more stable after more than 1000 h, compared to that of the DES-free cells. DES helped to stabilize and improve the photovoltaic performance of DSCs, particularly the short circuit current, due to the effect of the choline and phenol groups of DES binding on the TiO2 surface, as shown by the density functional theory (DFT) calculation. The optimal results were achieved with electrolyte containing 20% DES (efficiency = 6.9% with stable performance for more than 1000 h).

In this current work, a bifunctional TiO2 thin film with reduced pin-hole effect and enhanced light trapping capability was successfully fabricated by using a facile galvanostatic anodic deposition route in the presence of Brij-58 soft template (ST). The surface morphology of electrodeposited TiO2 thin film using ST confirmed the formation of nano-sized TiO2 particles with improved porous nature than that of TiO2 thin film electrodeposited in the absence of ST. Compared with the conventional scaffold porous layer (PL) fabricated from commercial mesoporous TiO2 composed of ∼30 nm nanoparticles, the electrodeposited TiO2 film using ST demonstrated the reduced pinhole effect and improved light trapping feature. Owing to the bifunctional behavior of electrodeposited TiO2 using ST, the cell efficiency of the perovskite solar cell was achieved up to 17.06% which was ca.10% higher than those with commercial TiO2 nanoparticles.

Power conversion efficiencies of perovskite solar cells depend heavily on the uniformity, coverage, grain size, and thickness of the perovskite layer. In this study, hybrid perovskite CH3NH3PbI3-xBrx thin films were fabricated from porous PbI2-xBrx layers prepared with a mixture solvent pore generation treatment process. The mixture solvent is composed of two anti-solvents of PbI2-xBrx to promote its crystallization, one with a low boiling point to accelerate the evaporative removal of the solvents of PbI2-xBrx, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and the other with a high boiling point to modulate the evaporative removal of DMF and DMSO to achieve a suitably configured porous structure for the PbI2-xBrx layer. With this fast pore generation treatment, uniform porous PbI2-xBrx layers were obtained within minutes, far more efficient than previously reported pore generation processes. The uniform porous PbI2-xBrx layer enabled formation of hybrid perovskite CH3NH3PbI3-xBrx thin films of low PbI2-xBrx residue, good crystallinity, low defect concentrations, and long charge carrier life times. The champion cell, assembled from the optimal hybrid perovskite thin films fabricated from optimized pore generation treatments, exhibited significantly superior power conversion performances of 19.26 mA/cm2 for the short circuit current density, 1.01 V for the open circuit voltage, 0.68 for the fill factor, and 13.16% for the power conversion efficiency, as compared to the average power conversion efficiency of 10.03% for non-porous PbI2-xBrx layer based cells.

In this study we attempt to develop an unprecedented approach to metallize diamond powder (DP) for diamond wire sawing (DWS) industry using electro less plating of cobalt/nickel (ELP Co/Ni) alloy without the need of additional electroplating step. This single step method allows efficient DP metallization process while maintaining good magnetic property. More importantly, the magnetism of resultant ELP Co/Ni film is easily manipulated by simply controlling the stoichiometry of metal precursors in ELP bath. The morphology, chemical composition and magnetic property of ELP Co/Ni film on the DP are carefully characterized. Tacking-on-density of DP on steel wire is proportional to the magnetism of ELP Co/Ni DP. Our study provides a simple, controllable and cost-effective process for advanced metallization of DP for DWS.

In this work, we pioneer to develop a process that combines a novel polymer-capped Pd nanoparticle as the catalyst in ELP and a special surface treatment which is able to create micro-craters on surface but without largely increasing surface roughness. Specifically, the catalyst agent was synthesized in the laboratory. We synthesized 2-5 nm Pd nanoparticles using polyvinyl alcohol (PVA) as the protecting agent in water. The PVA-Pd activator then work with a novel amine-based surfactant (polyethylenimine, PEI) via a molecular interaction between Pd core and amino-moieties on PEI. Due to this interaction, the adhesion of resultant ELP Cu on substrate is significantly enhanced. T-Peel adhesion of ELP Cu is further enhanced by applying a special surface roughening. This special surface treatment modifies traditional potassium permanganate desmear process but omitting swelling step in order to maintain the backbone structure of PID while mildly sculptures the surface to form micro-craters. Evaluated by water contact angle (WAC), scanning electron microscope (SEM) and surface profiler (alpha step), average T-peel adhesion of ELP-Cu on PID is enhanced from 185 to 571 gf/cm using this process. We believe this process paves a bright way for next generation SAP in advanced PCB application.

The use of molecular modulators to reduce the defect density at the surface and grain boundaries of perovskite materials has been demonstrated to be an effective approach to enhance the photovoltaic performance and device stability of perovskite solar cells. Herein, we employ crown ethers to modulate perovskite films, affording passivation of undercoordinated surface defects. This interaction has been elucidated by solid-state nuclear magnetic resonance and density functional theory calculations. The crown ether hosts induce the formation of host-guest complexes on the surface of the perovskite films, which reduces the concentration of surface electronic defects and suppresses nonradiative recombination by 40%, while minimizing moisture permeation. As a result, we achieved substantially improved photovoltaic performance with power conversion efficiencies exceeding 23%, accompanied by enhanced stability under ambient and operational conditions. This work opens a new avenue to improve the performance and stability of perovskite-based optoelectronic devices through supramolecular chemistry.

In this work, we have synthesized a novel porphyrin dye named SK7, which contains two N, N-diarylamino moieties at two β-positions as electron-donating units and one carboxy phenylethynyl moiety at the meso-position as an electron-withdrawing, anchoring group. This novel dye was tested for the application in dye-sensitized solar cells. The light-harvesting behavior of SK7 and YD2 was investigated using UV-vis absorption and density functional calculation. The electron transport properties at the TiO2/dye/electrolyte interface for SK7- and YD2-based devices were evaluated by electrochemical impedance spectroscopy. X-ray crystallographic characterization was conducted to understand the influence of two N, N-diarylamino units at two β-positions. The power conversion efficiencies of ca. 6.54% under 1 sun illumination (AM 1.5G) and ca. 19.72% under a T5 light source were noted for the SK7 dye. The performance of SK7 is comparable to that of dye YD2, which contains only one N, N-diarylamino moiety at the meso-position (ca. 7.78 and 20.00% under 1 sun and T5 light, respectively).

Amino-terminated silane compound modification was wet-processed on a silicon wafer using four different solvents to investigate the property of the self-assembled monolayer (SAM) and its influence on the adhesion of electroless deposited nickel-phosphorus (Ni-P) films. Analyzed by various tools including dynamic light scattering, the atomic force microscope, X-ray photoelectron spectroscopy, inductively coupled plasma with mass spectroscopy, a proper link between the processing solvent and SAM quality is established. It is found that at least the chemical compatibility, the polarity, and the acidity of solvents can affect the final morphology of the resultant SAM. Unlike toluene and ethanol that are most frequently chosen in literature, we conclude that isopropyl alcohol (IPA) is a superior solvent for amino-terminated silane compounds. Owing to the good SAM quality formed in IPA, the adhesion of electroless deposited Ni-P films is largely strengthened, even as high as the bulk strength of silicon wafers.

Selenium (Se) is one of the potential candidates as photodetector because of its outstanding properties such as high photoconductivity (∼8 × 104 S cm–1), piezoelectricity, thermoelectricity, and nonlinear optical responses. Solution phase synthesis becomes an efficient way to produce Se, but a contamination issue that could deteriorate the electric characteristic of Se should be taken into account. In this work, a facile, controllable approach of synthesizing Se nanowires (NWs)/films via a plasma-assisted growth process was demonstrated at the low substrate temperature of 100 °C. The detailed formation mechanisms of nanowires arrays to thin films at different plasma powers were investigated. Moreover, indium (In) layer was used to enhance the adhesive strength with 50% improvement on a SiO2/Si substrate by mechanical interlocking and surface alloying between Se and In layers, indicating great tolerance for mechanical stress for future wearable devices applications. Furthermore, the direct growth of Se NWs...

In this study, we report a facile method to sequentially electrodeposit a TiO2 compact layer and a mesoporous scaffold from a single solution. This bilayer TiO2 structure offers good controllability on the thickness and morphology by simply adjusting the depositing parameters. Currently, perovskite solar cell containing an electrodeposited TiO2 bilayer exhibits similar power conversion efficiency when compared with the one using double spin-coating techniques, showing great potential to replace conventional tedious TiO2 film fabrication.

Solvent engineering with dimethylsulfoxide (DMSO) has been shown to achieve high quality methylammonium lead iodide (MAPbI3) films for high performance perovskite solar cells (PSC). The morphology and composition of the intermediate PbI2-DMSO films play the key role for the success. The coordination and crystal growth of the PbI2–DMSO film however remain un-exploited. We study the way and extent of DMSO coordination and subsequent crystal growth of the PbI2-DMSO film to fabricate high quality perovskite films for enhancement of the photovoltaic performances of the cells. The DMSO is pre-coordinated or coordinated in-situ with PbI2 at a 1:1 or 2:1 M ratio. The PbI2-DMSO film from pre-coordination at 1:1 M ratio gives perovskite films of the best quality, being dense and possessing uniform size grains, high light absorption, and long charge carrier life times, among all investigated. The champion PSC achieves a high power conversion efficiency of 15.2%, significantly outperforming 13.0% of PSC based on PbI2-DMSO films from in-situ coordination at 1:1 M ratio, and 11.7% of PSC based on plain PbI2 films.

New D–A′–π–A type (D = electron donor, A′ = auxiliary acceptor, π = π-conjugated bridge, and A = electron acceptor/anchor) sensitizers with two bis(alkoxy)phenyl substituents incorporating thieno[3,4-b]pyrazines (TP) or a benzo[3,4-b]pyrazine (BP) entity as the auxiliary acceptor have been synthesized for application in dye-sensitized solar cells (DSSCs). Under 1 sun illumination, the DSSCs fabricated from the two BP dyes with a co-adsorbent have efficiencies of 8.39% and 9.03%, respectively. The latter surpasses that of the standard N719 dye (8.87%). Under dim light conditions MD7 exhibited a power conversion efficiency of 18.95% and 27.17% under 300 lux and 6000 lux irradiance, respectively.

The need for low-cost and highly efficient dyes for dye-sensitized solar cells under both the sunlight and dim light environments is growing. We have devised GJ-series push–pull organic dyes which require only four synthesis steps. These dyes feature a linear molecular structure of donor–perylene–ethynylene–arylcarboxylic acid, where donor represents N,N-diarylamino group and arylcarboxylic groups represent benzoic, thienocarboxylic, 2-cyano-3-phenylacrylic, 2-cyano-3-thienoacrylic, and 4-benzo[c][1,2,5]thiadiazol-4-yl-benzoic groups. In this study, we demonstrated that a dye without tedious and time-consuming synthesis efforts can perform efficiently. Under the illumination of AM1.5G simulated sunlight, the benzothiadiazole-benzoic-containing GJ-BP dye shows the best power conversion efficiency (PCE) of 6.16% with VOC of 0.70 V and JSC of 11.88 mA cm–2 using liquid iodide-based electrolyte. It also shows high performance in converting light of 6000 lx light intensity, that is, incident power of ca. 1.75 ...

The electrochemical reduction of CO2 is strongly influenced by both the applied potential and the surface adsorption status of the catalyst. In this work a gas diffusion electrode (GDE) coated with Pd nanoparticles/carbon black (Pd/XC72) was used to study the electrochemical reduction of CO2. Cyclic voltammetric (CV) analysis of Pd/XC72 between 1.5V and −0.6V (vs. RHE) shows the formation of intermediates and the blocking of hydrogen absorption on the Pd nanoparticles (NPs) under a CO2 atmosphere. The relationships between the Faradaic efficiency/current density and the applied potential reveal that the onset potential of CO formation is around −0.4V. Moreover, the presence of adsorbed CO was confirmed through CV analysis of Pd/XC72 under CO2 and CO/He atmospheres. This demonstrates that H atoms and CO intermediates co-adsorb on the surface of the Pd NPs at an applied potential of around −0.4V. When the applied potential is more negative than −0.6V, adsorption of CO intermediates on the surface of the Pd NPs becomes dominant. Keywords: Palladium nanoparticles, Applied potential, Carbon monoxide, Electrochemical reduction of carbon dioxide

Crystal morphology and structure are important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electronic, and photovoltaic devices. In particular, crystal growth and dissolution are two major phenomena in determining the morphology of methylammonium lead iodide perovskite in the sequential deposition method for fabricating a perovskite solar cell. In this report, the effect of immersion time in the second step, i.e., methlyammonium iodide immersion in the morphological, structural, optical, and photovoltaic evolution, is extensively investigated. Supported by experimental evidence, a five-staged, time-dependent evolution of the morphology of methylammonium lead iodide perovskite crystals is established and is well connected to the photovoltaic performance. This result is beneficial for engineering optimal time for methylammonium iodide immersion and converging the solar cell performance in the sequential deposition route. Meanwhile, our result suggests that large, well-faceted methylammonium lead iodide perovskite single crystal may be incubated by solution process. This offers a low cost route for synthesizing perovskite single crystal.

We present a facile and scalable method for preparing water-dispersed polyvinylpyrrolidone-capped graphene (PVP-graphene) nanoplatelets from an ordinary graphite powder. Three-dimensional hydrophobic graphite powder was exfoliated into two-dimensional hydrophilic PVP-graphene nanoplatelets by inducing intercalation by PVP chains and through high-powered sonication. The nanoplatelets were characterized through X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, and they were found to be nonoxidative and to have dimensions of a few hundred nanometers. The suitability of PVP-graphene as a catalyst for a cobalt(II)/(III) redox couple was evaluated by coating the prepared PVP-graphene nanoplatelets on fluorine-doped tin oxide glass through a unique two-step dipping method. The coated nanoplatelets were examined through electrochemical impedance spectroscopy, UV-vis spectroscopy, and current-voltage curve analysis, and it was observed that PVP-graphene exhibited high catalytic effect because the charge transfer resistance from cobalt(III) to cobalt(II) was as low as 1.17 Ω·cm2. A porphyrin-sensitized solar cell with this counter electrode and an efficiency of 8.95% was demonstrated.

Exploiting highly electrocatalytic and cost-effectiveness counter electrodes (CEs) in dye-sensitized solar cells (DSCs) has been regarded as a persistent objective. In this work, we proposed a facile low-cost solution approach for scalable fabrication of NiCo 2 S 4 (NCS) CEs in Pt-free DSCs. Firstly, NCS particles were synthesized by means of a solvothermal method. Afterwards, the NCS particles were successfully immobilized on fluorine-doped tin oxide (FTO) glass substrate and indium doped tin oxide polyethylene naphthalate (ITO/PEN) flexible substrate as NCS CE and flexible NCS CE, respectively, by using series of dip-coating processes. On the basis of extensive electrochemical characterizations, the NCS CEs displayed Pt-like electrocatalytic activity for I 3 − reduction. The DSC based on the NCS CE achieved an impressive cell efficiency of 8.94%, which was higher than that of the cell with the conventional Pt CE (8.51%). More interesting, the DSC using the flexible NCS CE still demonstrated an acceptable cell performance of 8.62% (or 8.57% with the bended flexible NCS CE).

A novel low-temperature augmentation of TiO2 using aqueous TiI4 solution is introduced for perovskite solar cells. The device based on TiO2 augmented with TiI4 electron transporting layer shows higher power conversion efficiency of 19.4% compared to 18.4% for standard TiO2 with an additional gain in device reproducibility. Covering the surface of TiO2 with iodide ions tunes its work function and shifts its conduction band increasing the open- circuit voltage of the photovoltaic device. Moreover, the mean particle size of perovskite material on the TiI4-augmented TiO2 increased from ~750 nm to ~950 nm. Augmentation of the electron transporting layer provides an effective route for efficient perovskite solar cells and other applications where surface modification is required.

In this study, a process for wet metallization on glass substrate involving adhesive electroless plating (ELP) is developed by integrating two material innovations. The first involves functionalizing a polymer-capped Pd nanocluster with amino silane compound to strengthen the adhesion between the ELP metal film and substrate. The second involves an additional nanoscaled TiO2 layer serving as the adhesion promoting layer (APL) coated on glass before metallization. After investigation with various tools, ELP metal film was observed to penetrate the mesoporous structure of TiO2 APL, reinforcing the adhesion of metallized film on glass through the mechanical anchoring effect. The formation of an interlayer between TiO2 APL and glass is not observed. A T-peel strength of 325 N m−1 is achieved. According to fracture analysis, the metal film/TiO2/glass structure breaks inside TiO2 APL, not TiO2 APL/glass, suggesting that further engineering developments are required to improve TiO2 APL coating.

In the last decade, inorganic–organic hybrid perovskites have demonstrated a dramatic increase in photoconversion efficiency by engineering the perovskite composition, as well as adjusting the properties of the charge transporting materials. The nucleation and growth of the perovskite layer are governed by the surface properties of the substrate and depend on its wetting properties defined by the roughness and the species adsorbed. Fixing all fabrication conditions of a PSC but only changing the wettability of the substrate is practically difficult because varying the surface hydrophilicity can contribute side effects such as chemical identity change or adsorption of new species on the surface. Herein, we studied a double-layered TiO2/SnO2 ETL for perovskite deposition and we changed the hydrophilicity of the samples using hydrophobic recovery after UV exposure. Thus, the effect of wettability of the substrate on nucleation and growth of the perovskite layer was elucidated under minimized interference. It was found that the influence of the wetting properties of the substrate on the growth of perovskite can be exaggerated in the literature since the increase in the grain size of the perovskite layer is just 14% bigger if the water contact angle of the substrate increases from 3° to 72°.

Addition of carbonaceous materials into transition metal sulfide counter electrode (CE) of a dye-sensitized solar cell (DSSC) is a common method to improve the performance of the CE and consequent photovoltaic performance. This improvement is almost without exception attributed to the improvement of overall conductivity after the carbonaceous material addition; however, the root function of these carbonaceous materials in promoting the solar cell efficiency is seldom discussed. In this study, highly crystallized nickel cobalt sulfide (NCS) micro-particles were mixed with a small portion of home-made reduced graphene oxide (rGO) nano-flakes. This NCS/rGO hybrid is subjected to extensive characterizations including X-ray diffraction, Raman spectroscopy, field emission scanning microscopy and electrochemical impedance spectroscopy. It is found that the rGO acts bi-functionally including a co-catalyst in accelerating the tri-iodide reduction for the main NCS catalysts, conductivity promotor to decrease the series resistance of the CE. Proved by electrochemical impedance spectroscopy, it is confirmed that the decrease in series resistance is less insignificant than that in charge transfer resistance, indicating rGO functions more profoundly as a co-catalyst than as a conductivity promotor. Moreover, an argument to highlight the requirement of a CE in a dim-light optimized DSSC is also proposed.

In this study, ultrasmall and ultrafine TiO 2 quantum dots (QDs) were prepared and used as a high-performance compact layer (CL) in dye-sensitized solar cells (DSCs). We systematically investigated the performance of TiO 2 CL under both low-intensity light and indoor fluorescent light illumination and found that the efficiency of DSCs with the insertion of optimal TiO 2 QDs-CL was increased up to 18.3% under indoor T5 fluorescent light illumination (7000 lux). We clarified the controversy over the blocking effect of TiO 2 CL for the efficiency increment and confirmed that the TiO 2 QDs-CL performed significantly better under low-intensity illumination due to the efficient suppression of electron recombination at the FTO/electrolyte interface. We, for the first time, demonstrate this potential for the application of the DSCs with TiO 2 QDs-CL in the low-intensity light and indoor fluorescent light illumination.

Front-side metallization of a Si wafer was carried out using electroless deposition of nickel-phosphorus (Ni-P) catalyzed by polyvinylpyrrolidone-capped palladium nanoclusters (PVP-nPd). A 3-[2-(2-Aminoethylamino)ethylamino] propyl-trimethoxysilane (ETAS) layer was covalently bonded on the Si surface as bridge linker to the Pd cores of PVP-nPd clusters for improving adhesion between the Ni-P layer and the Si surface. To investigate the effects of an interfacial ETAS layer on the Ni silicide formation at the Ni-P/Si contact, the Ni-P-coated Si samples were thermally annealed via rapid thermal annealing (RTA) from 500°C to 900°C for 2 min. To compare with the ETAS sample, the sputtered Ni layer on Si and electroless Ni-P layer on ion-Pd-catalyzed Si (both are standard processes) were also investigated. The microstructural characterizations for the Ni-P or Ni layer deposited on the Si wafer were performed using x-ray diffractometer, scanning electron microscopy, and transmission electron microscopy. Our results showed that the ETAS layer acted as a barrier to slow the atomic diffusion of Ni toward the Si side. Although the formation of Ni silicides required a higher annealing temperature, the adhesion strength and contact resistivity measurements of annealed Ni-P/Si contacts showed satisfactory results, which were essential to the device performance and reliability during thermal annealing.

We have devised a new porphyrin dye Y1A1 for photovoltaic applications under both light sources of AM1.5G standard conditions and low light intensity at 300–2400 lux. The dye Y1A1 is tailored with two 3,5-di-tert-butyl-4-methoxyphenyl groups at meso-10,20-positions which helps the solubility of the molecule in solvents and avoids involvement of the hazardous chemical n-butyllithium, which is used during the synthesis of some typical high efficiency porphyrins such as YD2-o-C8 and LD-series dyes. The dye is also structurally simple so that large-scale synthesis for future industrial applications becomes feasible. The Y1A1-based cells were found to exhibit higher performance using I−/I3− rather than Co2+/3+ electrolytes in the presence of CDCA co-adsorbent. The addition of Li+ additive to the GuSCN-free electrolyte benefits the performance in terms of higher capacitance at the compensation of surface charge recombination and electron lifetime. The optimized cells based on Y1A1 showed a power conversion efficiency of 9.22% under AM1.5G conditions and as high as 19.5% when illuminated under 350 lux of LED light.

Dye-sensitized solar cells (DSSCs) have attracted extensive attention for serving as potential low-cost alternatives to silicon-based solar cells. As a vital role of a typical DSSC, the counter electrode (CE) is generally employed to collect electrons via the external circuit and speed up the reduction reaction ofI3-toI-in the redox electrolyte. The noble Pt is usually deposited on a conductive glass substrate as CE material due to its excellent electrical conductivity, electrocatalytic activity, and electrochemical stability. To achieve cost-efficient DSSCs, reasonable efforts have been made to explore Pt-free alternatives. Recently, the graphene-based CEs have been intensively investigated to replace the high-cost noble Pt CE. In this paper, we provided an overview of studies on the electrochemical and photovoltaic characteristics of graphene-based CEs, including graphene, graphene/Pt, graphene/carbon materials, graphene/conducting polymers, and graphene/inorganic compounds. We also summarize the design and advantages of each graphene-based material and provide the possible directions for designing new graphene-based catalysts in future research for high-performance and low-cost DSSCs.

We have investigated the binding of two electrolyte additives, 4-tert-butylpyridine (4-TBP) and 2,2′-bipyridine (bipy), to the surface of TiO2 photo-anode by attenuated total reflection – Fourier transform infrared spectroscopy (ATR-FTIR); X-ray photoelectron spectroscopy (XPS); zeta potential; cyclic voltammetry analyses, and explained how the adsorption affects photovoltaic performance of dye-sensitized solar cell (DSC). To clarify whether the adsorption of 4-TBP/bipy on TiO2 surface affects the DSC performance, DSC devices were fabricated with non-grafted and 4-TBP or bipy grafted TiO2 photo-anodes, with application of two types of electrolytes with and without the nitrogen additives. Furthermore, the interaction between 4-TBP or bipy with the electrolyte mediator I−/I3− was investigated by cyclic voltammetry. The results showed that 4-TBP and bipy were able to bind chemically to TiO2 surface at elevated temperatures. DSC prepared with N-additive grafted TiO2 photo-anodes had lower short current and efficiencies than non-grafted cells. The open circuit voltage (Voc) was, however, increased 110 mV for 4-TBP grafted cells with 0.5 M 4-TBP in the electrolyte. One third of the overall increase in Voc was estimated to be due to the adsorption of the 4-TBP to the TiO2 surface. The remaining Voc increase was due to effects of 4-TBP on the electrolyte mediator.

This paper describes a unique and facile wet process to realize directly selective electroless deposition (ELD) on glass by controlling surface hydrophilicity and applying silane-compound equipped Pd nano-particles. In particular, 1H,1H,2H,2H- perfluorooctyltriethoxysilane (PFOTES) is formed to create a superhydrophobic surface on glass. Then the super hydrophobic surface is laser-patterned to allow partial glass surface naked. These exposed area is then activated by a self-attachable Pd nanoparticles because they are surrounded by amino-silane compound. Finally the Pd-activated area is metallized via ELD. Characterized by atomic force microscopy (AFM), water contact angle (WCA), optical microscope (OM), and X-ray photoelectron spectroscopic (XPS), it is found when the glass is coated with a thin 300 μm- TiO 2 (Ti-300) film and grafted with PFOTES, the WCA could exceeds 150°, while the WCA of the surface formed by small TiO 2 particles and PFOTES grafting lie between 110° to 140°. The superhydrophobic surface can repel Pd activators and thus result in no ghost plating. By contract, in the samples with less hydrophobic surface, ELD can occur randomly on unwanted area.

In this study, we renovated the sequential deposition route to fabricate a high-quality methylammonium lead iodide (MAPbI3) capping layer in scaffold-type PSCs from a low-toxicity aqueous lead nitrate precursor system. Through interpretation of the slow and stepwise conversion mechanism from lead nitrate to MAPbI3 in a methylammonium iodide bath, two key innovations, namely chloride inclusion in the methylammonium iodide bath and multiple-cycle immersion, were applied to remedy the flaws in the original MAPbI3 film. The PSC fabricated from the aqueous lead nitrate precursor through this renovated process showed remarkable stability over 55 days in an ambient dark chamber. Our work clearly indicates that using water as a processing solvent is irrelevant to the conversion efficiency or stability of a PSC and demonstrates no difference in the quality of PSC made by PbI2 /DMF protocol. This water-processed, environmentally friendly precursor system lights a direction of clean production of PSC using a minimal quantity of harmful organic solvents .