Study On Hybrid Solar Cell Based On Titanium Dioxide Nanorods Array

In this article, P3HT-CdS-TiO2orderly one-dimensional nanostructure hybridsensitized solar cells and Au-P3HT-CdTe-TiO2orderly one-dimensional nanostucture solidhybrid solar cells were fabricated based on the TiO2nanorods array from a hydrothermalmethod, and their energy conversion efficiencys are1.38%and0.91%respectively. Somefactors of the influence on the properties of hybrid solar cells are considered. The mainvaluable results and methods are listed as follows:First, TiO2nanorods arrays were prepared on the FTO conductive glass byhydrothermal method. The SEM analysis results showed that the microstructure of TiO2was nanorods arrays, the diameter of the nanorods arrays was about80nm, the length wasabout2.5microns; the XRD analysis result showed that the crystal type of the TiO2nanorods was rutile type; the transient photocurrent test showed that the wavelength of thelargest light response of the TiO2nanorods arrays was410nm. And the photon energy of410nm wavelength was about3.0eV. It was close to the forbidden band width of theexpected TiO2. It was suitable as the hybrid solar cells material of the latter experiment.Then, CdS nanoshells were prepared on the TiO2nanorods arrays byelectrodeposition, and the CdS-TiO2shell-core nanorods arrays were formed. The SEManalysis results showed that the diameter of the nanorods increased as the deposition time,after deposition of25min, the gaps among nanorods were almost disappeared, so it wasprobably not suitable for the later experiment; the XRD analysis proved that the addedmaterial on the nanorods arrays was CdS; the UV-visible absorption spectra showed thatthe absorption spectrum of the CdS-TiO2shell-core nanorods arrays was extended relativeto the TiO2nanorods arrays, the largest wavelength of the absorption spectrum is530nm,And the photon energy of530nm wavelength was about2.3eV. It was close to theforbidden band width of CdS. The CdS shell was suitable for the latter experiment.After that, a P3HT shell was deposited by electrodeposition on the CdS-TiO2shell-core nanorods arrays, and the P3HT-CdS-TiO2shell-core nanorods arrays wereformed. And the P3HT-CdS-TiO2one-dimensional orderly nanostructures hybridsensitized solar cells were form based on them, and the energy conversion efficiency wasdetermined. The SEM analysis results showed that P3HT was successfully coated on theCdS-TiO2shell-core nanorods arrays; the UV-visible absorption spectra showed that the absorption spectrum of the P3HT-CdS-TiO2nanostructure was extended a little relative tothe CdS-TiO2shell-core nanorods arrays, and the absorption intensity was improvedsignificantly; the open circuit voltage, short circuit current and the photoelectricconversion efficiency of the P3HT-CdS-TiO2hybrid sensitized solar cell was improvedsignificantly related to the CdS-TiO2semiconductor sensitized solar cell, it showed thatp-n hybrid sensitized structure has better photoelectric performance than the n typesemiconductor sensitized structure.In addition, CdTe narrow band gap semiconductor coated TiO2nanorods array wasformed by electrodeposition of CdTe nanocrystalline on the TiO2nanorods arrays. TheSEM analysis results showed that the CdTe was successfully coated on the TiO2nanorodsarray, but the gaps between the TiO2nanorods were filled up by the CdTe shell when thedeposition time of CdTe was as long as3h; the analysis results of XRD and EDS provedthat the new added material on the TiO2nanorods array was CdTe, and the proportions oftheir elements were good. The results of transient photocurrent tests showed that thephotoelectric performance of the CdTe-TiO2shell-core nanostructures is better than that ofTiO2nanorods arrays, and it grew as the deposition time grew, until3h. It may be due tothe enhancement of the thickness of the CdTe shell as deposition time grew, and thephoto-generated charge carriers cannot reach the solid-liquid separation for the too thicklyCdTe shell.Finally, the P3HT-CdTe-TiO2one-dimensional shell-core nanostructures was formedby spin-coating P3HT on the CdTe-TiO2shell-core nanorods arrays, and Au film wassputtered as cathode collector. Then, the photoelectric conversion performance wasmeasured, after the solid hybrid solar cell was formed with the P3HT-CdTe-TiO2nanostructure and copper foil sputtering gold. The analysis results of SEM showed that theP3HT was successfully coated on the CdTe-TiO2nanorods, and the Au film was filled thegap among the P3HT-CdTe-TiO2shell-core nanorods; the result of the transientphotocurrent tests of the P3HT-CdTe-TiO2nanostructure showed stability obviouslyanodic photocurrent under the electrode potential of0.2V, and showed cathodephotocurrent under the electrode potential of-1.4V. They showed p-type and n-typesemiconductor photoelectric properties,respectively. And it proved the existence of thep-n interface; the result of linear scanning in dark of the P3HT-CdTe-TiO2nanostructureshowed the unilateral conductivity of the p-n interface, and the result of linear scanningunder light showed the largest charge carrier mobility of these semiconductors(themaximum current), the reverse photocurrent phenomenon of the p-n interface under different voltage, they can reveal the direction how to optimize the solid inorganic-organichybrid solar cells.