Shaocong Hou

Integrated power fiber for energy conversion and storage

A new type of integrated power fiber that incorporates a dye-sensitized solar cell (DSSC) and a supercapacitor (SC), which can be used for energy conversation and storage, was introduced for the first time. A stainless steel wire coated with polyaniline via anodic deposition is jointly used as the electrode of the fiber DSSC and fiber SC. The overall energy conversion efficiency of the integrated power fiber is as high as 2.1%. Compared with traditional integrated power systems, our integrated power fiber is lightweight, flexible, inexpensive, suitable for special applications, and capable of integrating with cloth.

Nitrogen-doped graphene for dye-sensitized solar cells and the role of nitrogen states in triiodide reduction

Nitrogen-doped graphene was demonstrated as an efficient and alternative metal-free electrocatalyst for dye-sensitized solar cells. Electrochemical measurements showed that the nitrogen-doping process can remarkably improve the catalytic activity of graphene toward triiodide reduction, lower the charge transfer resistance, and thus enhance the corresponding photovoltaic performance. Furthermore, the nitrogen doping levels ranging from 3.5 at% to 18 at%, as well as the nitrogen states (including pyrrolic, pyridinic and quaternary configurations) in graphene, were controlled to interpret the roles of graphene structure in catalytic activity and device performance. The results suggested that the nitrogen states, rather than the total N content, have a significant effect on the catalytic activity. Both pyridinic and quaternary nitrogen states can provide active sites for promoting triiodide reduction reaction, probably due to the shift in redox potential and the lowered adsorption energy.

Transparent conductive oxide-less, flexible, and highly efficient dye-sensitized solar cells with commercialized carbon fiber as the counter electrode

TCO-less, flexible and highly efficient dye-sensitized solar cells are fabricated with commercialized carbon fiber as the counter electrode. 5.8% of conversion efficiency was obtained via modification of the conductivity and catalytic performance of carbon fiber.

Conjunction of fiber solar cells with groovy micro-reflectors as highly efficient energy harvesters

Solar cells are the most effective approach for sustainable energy to meet the worlds increasing needs in energy. However, their large-scale applications have been limited by low cost performance, supply of raw materials, complex preparation processes and the possible pollutions produced during processing. Here we introduce a novel fiber solar cell housed in a simple and low-cost parabolic-shape reflector, which can effectively capture diffuse light from all directions. The maximum efficiency of the fiber based dye-sensitized solar cells alone reached 7.02%. Furthermore, the maximum power output was enhanced by a factor of two and five, respectively, when the fiber was in conjunction with a diffuse reflector or a micro-light concentrating groove.

Graphite and platinum's catalytic selectivity for disulfide/thiolate (T2/T−) and triiodide/iodide (I3−/I−)

Dye-sensitized solar cells (DSSCs) using pure graphite sheet as the substrate and catalytic material were first fabricated based on a disulfide/thiolate (T2/T−) redox couple. It can present up to 4.79% of the power-conversion efficiency (PCE), compared with the 2.33% of triiodide/iodide (I3−/I−) redox couple at the same experimental condition under AM 1.5 illumination (100 mW cm−2). In contrast, when FTO/Pt is used as the counter electrode, PCE values are 3.97% and 7.13% based on the T2/T− and I3−/I−redox couples, respectively. With respect to the above dramatic difference, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) are applied to study the catalytic behavior at electrolyte (T2/T− and I3−/I−)/counter electrode (graphite sheet and FTO/Pt) interface. In particular, EIS indicated that the charge transfer resistance (RCT) (1.1 Ω cm2) of the graphite sheet for T2/T− is less than one-ninth of its RCT (10.2 Ω cm2) for I3−/I−. However, the RCT of FTO/Pt (7.7 Ω cm2) for T2/T− is more than twice the RCT (3.0 Ω cm2) of I3−/I−. This demonstrates the high catalytic selectivity of graphite and platinum (Pt) for the two redox couples. These results show the great potential of carbon materials to replace Pt by using this novel electron-transfer mediator in DSSCs.

Flexible conductive threads for wearable dye-sensitized solar cells

Flexible conductive threads were successfully fabricated on cheap insulating commercial thread substrates using a dip-coating method with conductive polymer PEDOT:PSS. The PEDOT:PSS improved the conductivity and catalytic performance of the threads. For the first time, threads were utilized to fabricate fiber-shaped dye-sensitized solar cells with 4.8% efficiency.

Direct application of commercial fountain pen ink to efficient dye-sensitized solar cells

Fountain pen ink possesses a well-dispersed nature and a relatively large specific surface area of carbon nanoparticles. In the present study, fountain pen ink was systematically studied and developed as cost-efficient counter electrodes (CEs) for planar dye-sensitized solar cells and fiber-shaped DSSCs (FDSSCs), which showed power conversion efficiencies above 6% under AM1.5G (100 mW cm−2). For ink-based planar solar cells, electrochemical impedance spectroscopy (EIS) confirmed that ink CEs had a slightly lower charge-transfer resistance than platinum CEs. EIS also proved that adding TiO2 nanoparticles into the ink could reduce the devices series resistance and the diffusion impedance of the electrolyte through electrode pores. For ink-based FDSSCs, the effects of film thickness, light intensities, and a comparative research of CE catalytic activities toward various electrolytes were discussed.

Dye-sensitized solar cells with vertically aligned TiO2 nanowire arrays grown on carbon fibers.

One-dimensional semiconductor TiO2 nanowires (TNWs) have received widespread attention from solar cell and related optoelectronics scientists. The controllable synthesis of ordered TNW arrays on arbitrary substrates would benefit both fundamental research and practical applications. Herein, vertically aligned TNW arrays in situ grown on carbon fiber (CF) substrates through a facile, controllable, and seed-assisted thermal process is presented. Also, hierarchical TiO2 -nanoparticle/TNW arrays were prepared that favor both the dye loading and depressed charge recombination of the CF/TNW photoanode. An impressive conversion efficiency of 2.48 % (under air mass 1.5 global illumination) and an apparent efficiency of 4.18 % (with a diffuse board) due to the 3D light harvesting of the wire solar cell were achieved. Moreover, efficient and inexpensive wire solar cells made from all-CF electrodes and completely flexible CF-based wire solar cells were demonstrated, taking into account actual application requirements. This work may provide an intriguing avenue for the pursuit of lightweight, cost-effective, and high-performance flexible/wearable solar cells.

Integration of fiber dye-sensitized solar cells with luminescent solar concentrators for high power output

For the first time, a novel solar device has been fabricated by integrating fiber dye-sensitized solar cells (FDSCs) with luminescent solar concentrators (LSCs) via a groove. Optical efficiencies from 8.27% to 22.05% have been achieved by the efficient solar devices. A Pmax up to 10 mW has been reached by fabricating a red solar module (70.56 cm2) with four FDSCs (5.50 cm). The high power output reduced the solar energy cost and showed the good potential application of the proposed device. The effects of electrolyte concentration, illumination area and light intensity were investigated in detail, which could be important in future module design.