Research On Titanium Dioxide Micro/Nano-Structure Modification And Its Photoelectric Properties

Energy is an important pillar for the social and economic development.While traditional fossil energy promotes economic development,it causes many problems to the environment,climate and human health.As a result,the research about renewable energy has attracted much attention all over the world.Solar energy has become a research hotspot in the field of new energy due to its advantages of cleanliness,convenience,inexhaustibility and low maintenance cost.Dye-sensitized solar cell?DSSC?and perovskite solar cell?PSC?,as the third generation of solar cells,have rapidly become a research hotspot for scientists.Both of them have the advantages of simple structure and process,low cost,transparency and flexible preparation.PSC is evolved from DSSC that both of the PSC and DSSC with sandwich structure.Semiconductor oxides are used as electron transport materials to extract and transport electrons excited by organic dyes and inorganic perovskite photosensitive materials.Therefore,the electronic transmission ability of photoanode plays an important role in the photoelectric performance of these batteries.The most commonly used semiconductor oxide of photoanodes is titanium dioxide.Among various morphologies of titanium dioxide nanomaterials,one-dimensional and two-dimensional nano-titanium dioxide has excellent electronic transmission ability,and is often used as photoanode materials in DSSC and PSC.In order to achieve higher photoelectric conversion efficiency,researchers have adopted various methods to improve the electronic transmission ability of the photoanode.This paper aims to improve the photoelectric conversion efficiency of solar cells by optimizing the structure and composition of DSSC and PSSC photoanodes and to analyze their mechanism.This paper has mainly investigated the following four aspects:?1?Effect of annealing atmosphere on photoelectric properties of titanium dioxide nanorod arraySingle crystal nanorod array of TiO₂ were prepared on FTO transparent conductive substrates by a simple hydrothermal synthesis.The structure,morphology,absorption and photoelectric properties of the nanorod array were investigated by annealing in air,argon and vacuum.The photocurrent,electrochemical impedance spectroscopy?EIS?and M-S Mott-Schottky characteristics of PEC with nanorods as photoanodes in different annealing atmospheres were studied.The results show that the depletion layer width of nanorods in different annealing atmosphere has the same trend with the performance of DSSC,which explains to some extent the effect of annealing on the performance of DSSC.Among them,air atmosphere is most conducive to the improvement the photoelectric conversion efficiency of DSSC,which is t from 0.98%to 4.4%.?2?Effect of carbon doped bonding layer on the photoelectric properties with TiO₂ nanotube array as photoanodeTiO₂ nanotube array were prepared on titanium sheets by anodic oxidation,and stripped from Ti substrates.Then the nanotube array were bonded to transparent conductive FTO substrates by using porous TiO₂ films.The graphene was prepared by Hummers method,and the mixture of graphene and acidified carbon nanotube was used as carbon source and doped into the porous film bonding layer to improve the electronic transmission ability of the bonding layer.The structure,morphology and photoelectric properties of the bonding layer before and after doping were studied.The experimental results show that incorporation of appropriate carbon materials can reduce the electronic transmission impedance of the photoanode and improve the photoelectric conversion efficiency of DSSC.When the doping amount is 0.1wt%,The PCE reaches a high point,which improved from 4.87%to 6.17%.?3?Effect of porous layer doped with TiO₂ nanosheet/nanotube on the performance of PSCNanosheet were stripped from TiO₂ nanoparticles by hydrothermal synthesis in alkaline solution.The nanosheet were curled into nanotube by changing the alkaline concentration.The structure,morphology and photoelectric properties of porous films doped with nanosheet/nanotube were studied.The experimental results show that the absorption ability of perovskite layer is improved after doping nanosheet/nanotube,and the photoelectric conversion efficiency of PSC is improved.When the doping amount of nanosheets or nanotubes is 1%,the efficienciy is increased from 13.2%to15.58%and 15.03%,respectively.?4?Effect of Nb/Ta doping porous layer on performance of PSC.Effect of Nb/Ta doping on the morphology,absorption spectra and PL spectra of porous and perovskite layers was studied.The experimental results show that the entry of Nb/Ta elements can not only improve the electronic transmission ability of the photoanode,but also improve the morphology of the perovskite layer,and enhance the photoelectric conversion efficiency of PSC.When the doping amount of Nb is 0.3wt%,The highist PCE improved from 13.74%to 14.82%.Similarly,When the doping amount of Ta is 0.5wt%,The highist PCE improved from 13.74%to14.95%.The electronic transmission performance of the porous layer is improved by doping carbon materialsor Nb/Ta element.The absorption efficiency for incident light and PCE of the solar cell is improved by doping the porous layer.It provides theoretical and technical support for the application of new solar cells.