Application Of Composite Transparent Electrodes Based On Silver Nanowires In Amorphous Silicon Solar Cells

Transparent conducting oxide?TCO?films not only have high optical transmittance in the visible light wavelength range but also have high conductive properties comparable to metal thin films,and consequently are widely used in various electronic devices.Up to now,it is known that many types of TCO are currently used in commercial silicon thin-film solar cells,such as:indium tin oxide?ITO?,tin oxide?SnO₂?,and zinc oxide?ZnO?.etc.Indium tin oxide films as a kind of high degenerate semiconductors with wide band gaps?band gap value range within 3.5-4.3 eV?,compared with other types of conductive films have better conductivity and higher visible light transmittance.However,in practical applications,indium tin oxide thin films will meet the following problems:?1?the main component of indium tin oxides is indium,which is a rare metal.With the increase in demand,their market price rises sharply;?2?some devices require the indium tin oxide films having a very low surface resistance.The ITO films need to increase their thickness under the same manufacturing process to reduce the surface resistance.When the film thickness exceeds 500 nm,the optical transmittance drops sharply,and the effect of the near infrared band is particularly obvious;?3?indium tin oxide films have poor mechanical elasticity and are not easy to bend.The films are easy to crack or even detach from the substrates under the action of external forces.They are not suitable as transparent electrodes for flexible devices.In order to solve the above problems,the following three aspects have been studied in this thesis:?1?Using ultrasonic spray coating technology,a layer of grid-shaped silver nanowire?Ag NW?thin film was prepared on a fluorine-doped tin oxide?FTO?conductive substrate.This thesis explores the effect of Ag NW mesh films with different coverage on the performance of FTO films.The tested results showed that the addition of Ag NW layer does not significantly affect the optical transmittance of the FTO film,but the surface resistance was significantly reduced,the lowest value is 7.28?/sq,and the reduction rate is 8.2%.The thin film mechanism analysis proved that the addition of Ag NW layer will enhance the carrier transport characteristics.The optimized parameters of the amorphous silicon solar cell are:(1_oc=889 mV,_sc=14.52mA/cm²,=63.3%,?(_ff)=7.9%.Among them,the short-circuit current increased by 11%,and the conversion efficiency increased by 20%.?2?Combined with radio frequency magnetron sputtering and ultrasonic spraying,a flexible transparent conductive ITO/Ag NW double-layer film was prepared on a polyethylene terephthalate?PET?substrate.The tested results showed that the Ag NW layer can protect the ITO film from cracking after bending.The mechanical flexibility of ITO/Ag NW double-layer films is superior to that of single-layer ITO films,and the former are more suitable as substrates for flexible devices.The functional layer of amorphous silicon solar cells was prepared on the front electrode of ITO/Ag NW by plasma enhanced chemical vapor deposition?PECVD?.Then the amorphous silicon absorber layer was optimized to be thinned as 100 nm.In this way,an ultra-thin translucent flexible amorphous silicon solar cell with a photoelectric conversion efficiency of 5.32%was prepared.?3?Three-layer conductive films of ITO/Ag NW/ITO with proper optical and electrical properties were prepared by combining the magnetron sputtering and ultrasonic spraying.