Leqing Fan

A large-area light-weight dye-sensitized solar cell based on all titanium substrates with an efficiency of 6.69% outdoors.

Light-weight PEDOT-Pt/Ti mesh and Ti/TiO(2) foil electrodes are prepared. Owing to the PEDOT-Pt/Ti photocathodes high transparency, good electrocatalytic activity, and low resistance; the Ti/TiO(2) anodes large specific area and high conductivity, a light-weight backside illuminated large-area (100 cm(2) ) dye-sensitized solar cell achieves an energy conversion efficiency of 6.69% under an outdoors sunlight irradiation of 55 mW cm(-2) .

A simple and high-effective electrolyte mediated with p-phenylenediamine for supercapacitor

A redox intermedium p-phenylenediamine (PPD) with quick reversible faradaic processes is introduced into KOH electrolyte, referred to as pseudocapacitive effect occurring on the electrode/electrolyte surface. The KOH + PPD electrolyte as potential electrolyte for supercapacitors is investigated by UV-Vis spectroscopy and electrochemical methods. As expected, the supercapacitor with KOH + PPD electrolyte has a much higher electrode specific capacitance (605.225 F g−1) than the one with conventional KOH electrolyte (144.037 F g−1) at the same current density of 1 A g−1. Simultaneously, the supercapacitor with KOH + PPD electrolyte exhibits a much higher energy density (19.862 W h kg−1) than the supercapacitor with conventional KOH electrolyte (4.458 W h kg−1). Furthermore, the supercapacitor with KOH + PPD electrolyte shows superior charge–discharge stability. After 4000 cycles, its capacitive retention ratio is still as high as 94.530%.

Redox-active alkaline electrolyte for carbon-based supercapacitor with pseudocapacitive performance and excellent cyclability

A simple method has been implemented to prepare a stable and effective redox-active alkaline electrolyte by doping m-phenylenediamine into a conventional KOH electrolyte for a carbon-based supercapacitor. The quick electron transfer and reversible Faradic process in the new electrolyte system results in additional pseudocapacitive contribution for a carbon-based supercapacitor. The specific capacitance of the supercapacitor based on the new electrolyte is 78.01 F g−1, which is an increase of 114.16% over that of a supercapacitor based on a conventional KOH electrolyte (36.43 F g−1). Additionally, the supercapacitor exhibits an excellent cyclical stability.

A high performance Pt-free counter electrode of nickel sulfide/multi-wall carbon nanotube/titanium used in dye-sensitized solar cells

Multi-wall carbon nanotubes (MWCNTs) were deposited on a titanium (Ti) foil substrate by using electrophoresis, then a nano-corallines nickel sulfide (NiS) was deposited on the MWCNTs by using a pulse potentiostatic method. The high performance NiS/MWCNT/Ti hybrid film was firstly used as a Pt-free counter electrode (CE) in dye-sensitized solar cells (DSSCs). The surface of MWCNTs was wrapped with a nano-corallines NiS thin film of ∼45 nm in thickness. Under full sunlight illumination (100 mW cm−2, AM 1.5 G), DSSCs with a NiS/MWCNT/Ti CE achieved an enhanced photovoltaic conversion efficiency of 7.90%, while DSSCs with a Pt/Ti CE obtained the efficiency of 6.36%. The characterization of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicated that nano-corallines NiS had high electrocatalytic activity for I3− reduction, MWCNTs had high specific surface area and low resistance, and the synergistic effect of NiS and MWCNTs endowed the superior features of the hybrid film. Therefore, the NiS/MWCNT/Ti CE can be used as a promising alternative CE in low-cost and large-scale DSSCs.

Dual functions of YF3:Eu3+ for improving photovoltaic performance of dye-sensitized solar cells

In order to enhance the photovoltaic performance of dye-sensitized solar cell (DSSC), a novel design is demonstrated by introducing rare-earth compound europium ion doped yttrium fluoride (YF3:Eu3+) in TiO2 film in the DSSC. As a conversion luminescence medium, YF3:Eu3+ transfers ultraviolet light to visible light via down-conversion, and increases incident harvest and photocurrent of DSSC. As a p-type dopant, Eu3+ elevates the Fermi level of TiO2 film and thus heightens photovoltage of the DSSC. The conversion luminescence and p-type doping effect are demonstrated by photoluminescence spectra and Mott-Schottky plots. When the ratio of YF3:Eu3+/TiO2 in the doping layer is optimized as 5 wt.%, the light-to-electric energy conversion efficiency of the DSSC reaches 7.74%, which is increased by 32% compared to that of the DSSC without YF3:Eu3+ doping. Double functions of doped rare-earth compound provide a new route for enhancing the photovoltaic performance of solar cells.

Glucose aided preparation of tungsten sulfide/multi-wall carbon nanotube hybrid and use as counter electrode in dye-sensitized solar cells.

The tungsten sulfide/multi-wall carbon nanotube (WS(2)/MWCNT) hybrid was prepared in the presence of glucose by the hydrothermal route. The hybrid materials were used as counter electrode in the dye-sensitized solar cell (DSSC). The results of cyclic voltammetry measurement and electrochemical impedance spectroscopy indicated that the glucose aided prepared (G-A) WS(2)/MWCNT electrode had low charge-transfer resistance (R(ct)) and high electrocatalytic activity for triiodide reduction. The excellent electrochemical properties for (G-A) WS(2)/MWCNT electrode is due to the synergistic effects of WS(2) and MWCNTs, as well as amorphous carbon introduced by glucose. The DSSC based on the G-A WS(2)/MWCNT counter electrode achieved a high power conversion efficiency of 7.36%, which is comparable with the performance of the DSSC using Pt counter electrode (7.54%).

An ultraviolet responsive hybrid solar cell based on titania/poly(3-hexylthiophene)

Here we present an ultraviolet responsive inorganic-organic hybrid solar cell based on titania/poly(3-hexylthiophene) (TiO2/P3HT) heterojuction. In this solar cell, TiO2 is an ultraviolet light absorber and electronic conductor, P3HT is a hole conductor, the light-to-electrical conversion is realized by the cooperation for these two components. Doping ionic salt in P3HT polymer can improve the photovoltaic performance of the solar cell. Under ultraviolet light irradiation with intensity of 100 mW·cm−2, the hybrid solar cell doped with 1.0 wt.% lithium iodide achieves an energy conversion efficiency of 1.28%, which is increased by 33.3% compared to that of the hybrid solar cell without lithium iodide doping. Our results open a novel sunlight irradiation field for solar energy utilization, demonstrate the feasibility of ultraviolet responsive solar cells, and provide a new route for enhancing the photovoltaic performance of solar cells.

Improving the energy density of quasi-solid-state electric double-layer capacitors by introducing redox additives into gel polymer electrolytes

A redox-active gel polymer electrolyte was prepared by introducing KI/VOSO4 redox additives into a polyvinyl alcohol–H2SO4 gel electrolyte for application in a quasi-solid-state electric double-layer capacitor (EDLC) based on activated carbon. The EDLC obtained had a high electrode-specific capacitance of 1232.8 F g−1 and a high energy density of 25.4 W h kg−1; these values are higher than that of an EDLC with a conventional gel electrolyte. The improved energy storage is attributed to Faradaic pseudocapacitance related to the redox-active ions in the gel polymer electrolyte.

Application of a novel redox-active electrolyte in MnO 2 -based supercapacitors

This paper reports a novel strategy for preparing redox-active electrolyte through introducing a redox-mediator (p-phenylenediamine, PPD) into KOH electrolyte for the application of ball-milled MnO2-based supercapacitors. The morphology and compositions of ball-milled MnO2 were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical properties of the supercapacitor were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The introduction of p-phenylenediamine significantly improves the performance of the supercapacitor. The electrode specific capacitance of the supercapacitor is 325.24 F g−1, increased by 6.25 folds compared with that of the unmodified system (44.87 F g−1) at the same current density, and the energy density has nearly a 10-fold increase, reaching 10.12 Wh Kg−1. In addition, the supercapacitor exhibits good cycle-life stability.

A Reversible Redox Strategy for SWCNT‐Based Supercapacitors Using a High‐Performance Electrolyte

In order to achieve pesudocapacitive performance of single-wall carbon nanotube (SWCNT) electrodes, a high-efficient and reversible redox strategy utilizing a redox-mediated electrolyte for SWCNT-based supercapacitors is reported. In this novel redox-mediated electrolyte, the single-electrode specific capacitance of the supercapacitor is heightened four times, reaching C=162.66 F g(-1) at 1 A g(-1). The quick charge-discharge ability of the supercapacitor is also enhanced, and the relaxation time is as low as 0.58 s. Furthermore, the supercapacitor shows an excellent cycling performance of 96.51 % retention after 4000 cycles. The remarkable results presented here illustrate that the redox strategy is a facile and straightforward approach to improve the performances of SWCNT electrodes.