Zhibin Lv

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.

Influence of Electrolyte Refreshing on the Photoelectrochemical Performance of Fiber-Shaped Dye-Sensitized Solar Cells

Given the convenient sealing of fiber-shaped dye-sensitized solar cells (FDSSCs), the electrolyte refreshing effect on the photo-electrochemical performance of FDSSCs was studied. The electron transport and interfacial recombination kinetics were also systematically investigated by electrochemical impedance spectroscopy. With increased electrolyte refreshing times from 0 to 10, the open-circuit voltage (Voc) and fill factor (FF) increased, whereas the photocurrent density (Jsc) and power conversion efficiency (PCE) significantly decreased. The increased Voc was mainly ascribed to the electron recombination resistance (Rct, WE) at the TiO2/electrolyte interface and electron lifetime. The decreased Jsc and PCE were due to dye desorption and the increase of series resistance. Further investigation proved that Li

Fiber Solar Cells

Flexible solar cells with the advantages of lightweight, foldability, and low cost, and extensive applications have attracted much academic interest and industrial attention during the last decades. The superiority of fiber cell is the most significant advantage of all non-flat-structured solar cells: 1. The non-flat structured solar cell gets rid of the dependence on transparent conductive oxide. 2.The fiber cell, which has a three-dimensional (3-D) structure, can catch photons from all directions to increase the power output of cells for improved optical structure capability. Meanwhile, the fiber cell has very low dependence on incident light angle and can gather diffused reflected light to maintain weatherproof and stable power output. 3. The fiber cell is a macro 1-D structure and has a smaller package area ratio than the 2-D structure. Making a larger cell requires only increasing the length of the cell. 4. The flexible fiber cell can directly adopt traditional preparation technology, whereas special technologies must be adopted to make all kinds of traditional flexible flat cells (like OPV and DSSC) to ensure that the flexible substrate will not be damaged during the preparation process, such as by low temperature. 5. Existing textile techniques can be directly used in weaving for mass production of fiber cells, another further improvement of the traditional roll-to-roll technology for producing flexible electrical devices. This chapter reviews the various types of fiber-shaped flexible solar cells and their characteristics.