Application Of Polyaniline In Sb₂S₃/SnS Sensitized Solar Cells

Due to the reserved limitation of the conventional fossil fuels in earch, the fossilfuels will be utterly consumed in the21st century. So seeking for clean and renewableenergy has caused the world wide concern, and we must solve this problem. The solarenergy is clean and will be never used up. Making one kind of photoelectrochemicalsolar cell with low cost and relatively high energy conversation efficiency is one ofmain way to use solar energy.Dye-sensitized solar cells have become a major research and development topicas a new type of photovoltaic solar cells during the past two decades. Instead of usinga molecular dye, a semiconductor absorber can also be used as light absorber. Suchsemiconductor sensitized solar cells either named as extremely thin absorber solar cells orquantum dot sensitized solar cells are much less studied than dye-sensitized solarcells but are attracting increasing interest. Some kinds of metal chalcogenidesemiconductor absorbers such as CdS, CdSe, PbS, PbSe, Sb₂S₃and so on have beenused in quantum dot sensitized or extremely thin absorber solar cells. Thecontinuously increased power conversion efficiency of these devices is obtained. Thispaper used PAn as a kind of solid state electrolyte and a catalytist in counterelectrodes in the solar cells, respectively. The paper mainly obtained the followingconclusions.1) The synthesis of various materials such as Sb₂S₃-sensitized TiO₂films、SnSsensitized nanocrystallite TiO₂photoanodes and polyaniline:Chemical bath deposition （CBD） method was used to fabricate Sb₂S₃sensitizednanocrystallite TiO₂photoanodes. Their surface morphology and light adsorptionwere measured with SEM, TEM and UV-vis adsorption spectra, respectively. Byoptimizing the preparation conditions, it was found that the Sb₂S₃-sensitized TiO₂photoanode prepared with CBD method in the solution containing acetic acidshowed higher light absorption in short-wavelength region compared with that ofthe one prepared with CBD method in the solution containing acetone. Byoptimizing CBD solution concentration and optimizing CBD duration in the timeof2.5h, it was found that the Sb₂S₃-sensitized layer in the photoanode is nanostructure, as that of the traditional quantum dot, the photoactive electrodewith the thin Sb₂S₃-sensitized layer shows higher light absorption compared withthat of the one with the thick Sb₂S₃-sensitized layer. SnS-sensitized TiO₂filmswere prepared with successive ionic layer adsorption and reaction （SILAR）method. It was found that the cell assembled with the photoanode fabricated by9times of SILAR circulation, showed higher light absorption. It is seen that thedried PAn aqueous dispersion on the Sb₂S₃-sensitized TiO₂film can form a wellconnected porous network-like PAn layer originating from its nanobeltmorphology, which is beneficial to be used as hole transporter in the Sb₂S₃-sensitized solar cells.2) Research on the solar cells with Sb₂S₃-sensitized layers and polyaniline solidstate electrolyte：In order to investigate the photovoltaic performance of these Sb₂S₃-sensitizedTiO₂films, a photoelectrochemical solar cell containing a Sb₂S₃-sensitized TiO₂photoanode, polyaniline hole-transporter, and a Pt counter electrode wasprepared. Their photovoltaic performance was measured. The cells assembledwith these different components showed different photovoltaic performance. Itwas found that the Sb₂S₃-sensitized TiO₂photoanode prepared with CBDmethod in the solution containing acetic acid showed lower charge transferresistance and longer electron lifetime compared with that of the one preparedwith CBD method in the solution containing acetone, resulting in betterphotovoltaic performance. The power conversion efficiency of the cells is0.71%and0.88%, respectively. In order to improve the power conversionefficiency, the concentration of CBD solution and CBD duration time wereoptimized. It was found that when using low concentration of the solution andselected2.5h of CBD duration time, the performance of the cell could beimproved due to the decreased charge transfer resistance and longer electronlifetime compared with that of the one with the thick Sb₂S₃-sensitized layer. Thecell could obtain6.92mA·cm-2short-circuit current density,1.098Vopen-circuit voltage,0.497fill factor, and3.78%power conversion efficiency.3) Research on the solar cells with SnS sensitized layers and polyaniline counter electrodes:A method of successive ionic layer adsorption and reaction （SILAR） was used tofabricate SnS sensitized nanocrystallite TiO₂photoanodes. Their surfacemorphology, crystal structure, UV-vis adsorption and diffusion properties weremeasured with XRD, TEM, UV-vis adsorption and diffusion spectra, respectively.The photovoltaic performance of photoanodes were measured throughassembling SnS sensitized solar cells with these photoanodes, counter electrodescontaining polyaniline or platinum catalyst, liquid electrolyte containing iodineor sulfur redox couple. The cells assembled with these different componentsshowed different photovoltaic performance. It was found that the cell assembledwith the photoanode fabricated by9times of SILAR circulation, the counterelectrode of polyaniline-stainless steel net, and the liquid electrolyte containingsulfur redox couple showed the highest photovoltaic performance. Theshort-circuit current density, open-circuit voltage, fill factor, and powerconversion ef-ficiency could attain to4.59mA·cm-2,0.547V,0.505and1.27%,respectively...