The Study On Interface Engineering In Electron Transporting Layer For Organic And Perovskite Solar Cells

Solar cells that can directly convert the solar energy to electricity has been acknowledged as a promising approach to deal with the fast-growing energy demands and to address the increasing concerns of environment pollution problem caused by the using of fossil fuels.Particularly,in recent years,organic solar cells(OSCs)and Perovskite solar cells(PSCs)have drawn extensive attention mainly due to their advantages of low-cost,easy to fabricate,light weight and compatible with a flexible substrate,.Recently,through interfacial engineering,optimizing the device fabrication process and the use of appropriate active layer materials,the state-of-the-art power conversion efficiencies(PCEs)of OSCs and PSCs have been rapidly enhanced However,to pave the way for their viable and practical application of OSCs and PSCs,further enhancement in PCEs for the OSCs and PSCs still highly demand.For both OSCs and PSCs,insert an appropriate electro transporting layer(ETLs)between photo-active layer and cathode is essential to achieve high device efficiency.It has been demonstrated that the surface modification of ETLs is highly desirable to achieve a high PCE and good device-stability.In this work,by using the method of interface engineering,through structure regulation and the surface modification of ETLs and thus optimizing the performance of OSCs and PSCs.Detailed research contents inclduing the following three aspects:(1)Doule-sided surface modification of ZnO ETL using ultra-thin reduced graphene oxide(r-GO)and titanium dioxide(TiO2)layers.The interfaces of active layer/ZnO and ZnO/cathode were modified by r-GO and TiO2,repspectively.To optimize the device performance,the effects of the thickness of r-GO and TiO2 layers on device performance were also investigated.We found that the best device performance is achieved using the ZnO ETL modified by r-GO and TiO2 thin layers derived from 0.5 mg mL-1 and 0.1 M,respectively.Compared to the control device based on the pristine ZnO films,the average PCEs of the devices with double-sided modified ZnO ETLs modified by r-GO and TiO2 layers are remarkably enhanced up to 23.6%and 13.3%for P3HT:PC61BM and PTB7:PC71BM blend system,respectively.The PCEs enhancement mainly result from the enhanced electron transportation and collection efficiency,reduced interfacial energy losses,and better energy level alignment.(2)We prepared ZnO nano-rod arrays using a hydrothermal method,and coated an ultra-thin aluminum oxide(Al2O3)coating layer to modifiy the surface of ZnO nanorods.The experimental results shows that the photovotaic performance of the OSCs based on the ZnO nano-arrays coated with Al2O3 has been significantly enhanced.The improvements in device performance mainly own to the increased contact area between the active layer and ZnO nano-rod arrays.(3)We demonstrated a new strategy to adjust the dispersity and spatial distribution of the plasmonic Au NPs in the active layer of OSCs and PSCs via self-assembly and reactive ion etching(RIE)routes.Prior to the RIE treatment,the plasmonics metal NPs are self-assembled on the metal oxide(here is the TiO2)buffer layer first.Then the reactive ion etching(RIE)method is used to construct height adjustable metal NPs arrays.The height adjustable TiO2 rod-Au NPs arrays could be used to control the spatial distribution of the Au NPs in the covered active layers for optimizing the LSPR and scattering effects of Au NPs on the light-absorption of active layer.