Study On Photoelectrical Properties Of Quantum Dots Sensitized Solar Cell In Magnetic Field

It is clear that access to economically viable renewable energy sources is essential for thedevelopment of a globally sustainable society. Dye-sensitized solar cell （DSSC） as a newphotovoltaic solar cell has been an active research project because of their simple preparationprocess and low cost. However, its low light-to-energy conversion efficiency and poorlong-term reliability limit its large-scale application.The basic electron transfer processes in a DSSC consist the generation, recombination andinterface migration of photo-induced carrier in semiconductors. During these processes, theact of electrons and holes plays a significant role, which would be easily influenced by themagnetic field. Therefore, we considered that the magnetic field might affect the cell’sphotoelectrical properties and quantum efficiency via the influence on the behavior ofelectrons and holes. In the present works, some undesirable problems still exist in DSSC, suchas low transfer rate of photo-anode electronic mobility and serious recombination of electronsand holes. In order to accelerate the DSSC conversion, an external magnetic field wasintroduced to improve the electron-hole separation process by the effects of Lorenz force.In this paper, we researched the influence of external magnetic field on the photoelectricalproperties of DSSCs, whose photo-anodes are sensitized TiO₂and ZnO nanorod-array by CdS,PbS, CdSe quantum dots （QDs） and N719dye. The results showed that the present of externalmagnetic field improves the Jsc （8.32mA/cm²-10mA/cm²） and efficiency （4.68%-5%） ofmesoporous TiO₂solar cells sensitized with N719dye. An evident improvement of Jsc（1.92mA/cm²-2.66mA/cm²）, and efficiency （0.34%-0.55%） on the ZnO solar cells, sensitizedwith CdS QDs, was also achieved. Base on the date of photoanode film resistance and thedark current with and without external magnetic field, it was found that the Lorenz forcechange the movement-direction of the photo-induced electrons and holes, which promoted theseparation of photo-induced electrons and holes, resulting in an increase of the cell efficiency.This facile method would be an effective approach to improve the efficiency of DSSCs.A template-free hydrothermal method is used to prepare large-scale ZnO hollowmicrospheres with core/shell structures.This structure has high surface area that wouldincrease the amount of dye adsorption.It also has scattering effect for incident light whichextend the transmission path of the light in the photoanode and ultimately improve theefficiency of the DSSC.