Zengze Chu

Conductive mesh based flexible dye-sensitized solar cells

Conductive meshes are used to replace transparent conducting oxides (TCOs), which are commonly used in electrodes of dye-sensitized solar cells (DSSCs). The TCO-less flexible working electrode could be sintered under 400–500°C. A preliminary result that open-circuit voltage (VOC)=650mV, short-circuit current density (ISC)=4.5mA∕cm2, and efficiency (ηAM1.5)=1.49% (100mW∕cm2) is obtained from the liquid-type DSSC. The incident light could be dispersed uniformly inside the electrode. Testing results of the double-counterelectrode cell indicate that the transmission of electrolyte is not the rate-determining step. The dense TiO2 layer is critical in improving the cell’s performances.

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.

Fibrous flexible solid-type dye-sensitized solar cells without transparent conducting oxide

We have explored a type of all-solid fibrous flexible dye-sensitized solar cells without transparent conducting oxide based on a CuI electrolyte. The working electrode’s substrate is a metal wire. Cu wire counterelectrode is twisted with the dye-sensitized and CuI-coated working electrode. The cell’s apparent diameter is about 150μm. The cell’s current-voltage output depends little on the incident angle of light. A 4-cm-long fibrous cell’s open-circuit voltage and short-circuit current generate 304mV and 0.032mA, respectively. The interfacial interaction between the two electrodes has a significant influence on the inner charge transfer of the cell.

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.

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.