Jinghao Huo

An in situ polymerized PEDOT/Fe3O4 composite as a Pt-free counter electrode for highly efficient dye sensitized solar cells

3,4-Ethylenedioxy thiophene (EDOT) precursor solution doped by Fe3O4 was spin-casted onto fluorine doped tin oxide (FTO) glass and formed poly(3,4-ethylenedioxy thiophene) (PEDOT)/Fe3O4 hybrid films by an in situ polyreaction. The films were utilized as the counter electrode in dye sensitized solar cells (DSSCs). Photoelectric conversion efficiency (PCE) for DSSCs based on PEDOT/Fe3O4 varied with the content of Fe3O4 in the precursor solution. When the content of Fe3O4 was 2 mg ml−1 in the precursor solution (PEDOT/Fe3O4-2), the best performance (8.69%) was obtained. In comparison, that of a DSSC with a Pt counter electrode is 8.35%. According to the surface microtopography and electrochemical analysis, large active areas, consecutive electronic transmission channels and lower charge transfer resistance could be responsible for the high PCE.

Hydrothermal synthesis of CoMoO4/Co9S8 hybrid nanotubes based on counter electrodes for highly efficient dye-sensitized solar cells

CoMoO4/Co9S8 hybrid nanotubes were fabricated by a simple two-step hydrothermal method, which was similar to that for preparing Co9S8 nanotubes. Then the CoMoO4/Co9S8 nanotubes were coated onto fluorine-doped tin oxide glass to fabricate a counter electrode (CE) by spin-casting. Field emission scanning electron microscopy images show that the introduction of CoMoO4 to Co9S8 makes the surface of the CoMoO4/Co9S8 nanotubes rougher. Cyclic voltammetry shows that the electrocatalytic activity of the CoMoO4/Co9S8 CE is similar to that of a Pt CE when the (NH4)2MoO4 content was 60 wt%. Meanwhile, the electrochemical impedance spectroscopy and Tafel measurements demonstrated that the CoMoO4/Co9S8 CE had smaller values of Rs and Rct than a Pt CE. The dye-sensitized solar cells assembled with a CoMoO4/Co9S8 CE achieved excellent values of open-circuit voltage (0.743 V), short-circuit current density (17.276 mA cm−2), fill factor (0.670) and a wonderful power conversion efficiency (8.60%), which is higher than that of DSSCs with a Co9S8 CE (7.69%) or a Pt CE (8.13%) under the light intensity of 100 mW cm−2 (AM 1.5 G).

Improving the photovoltaic performance of a dye-sensitized solar cell by using a hierarchical titania bur-like microspheres double layered photoanode

Three-dimensional hierarchical titania bur-like microspheres (TiO2 BMs) composed of nanowires were synthesized by a hydrothermal method, and possess a specific surface area of 114 m2 g−1 and a main pore size of 6 nm. The one-dimensional nanowire ensures faster electron transport and a longer electron recombination time than titania nanoparticles (TiO2 NPs). Therefore, a film based on the TiO2 BMs exhibits excellent light scattering properties and thus enhances light harvesting efficiency. Using a TiO2 BM film as a scattering layer on the top of a compact TiO2 NP film, the double layered dye-sensitized solar cell (DSSC) shows a power conversion efficiency of 7.31%, indicating a 10.2% and 15.1% improvement compared to the DSSCs based on TiO2 NP and TiO2 BM single films, respectively.