The Research On High Efficiency Organic Solar Cells Based On Interface Control

Finding enough clean energy has become a key issue related to the sustainable and healthy development of human society.Solar energy,which accounts for 99% of the total energy of the earth,has undoubtedly become the best choice for people.Organic solar cells have attracted extensive attention due to their excellent photoelectric properties.In particular,a large number of high-performance organic photovoltaic materials have been synthesised in recent years,the power conversion efficiency(PCE)of binary organic solar cells has exceeded 15%.In this paper,we mainly through interface control to improves the device performance of organic solar cells.The main research contents are as follows:(1)In this paper,a novel small-molecule zwitterionic electrolyte(S1)was introduced as the interface modification layer of electron-transporting layer(ZnO).The experimental results show that the zwitterionic side chains of S1 create a double dipole at the interface induced by the electrostatic realignment.So that the S1/ZnO layer has an ultra-low work function of 3.6 eV.Adding S1 interfacial modification layer can form better energy level matching,improve the ability of charge extraction,inhibit the compound loss of charge and reduce the series resistance of active layer/electrode.Compared with the PCE of standard devices(7.4%),the PCE of devices modified by S1 increased by 20% to 8.89%.(2)At present,it is difficult to control the interface structure of ternary blend film,which limits the further development of ternary organic solar cells.In this work,we introduce high crystalline polymer N2200 as the third component to construct ternary organic solar cells.The addition of 10 wt% N2200 not only expands the spectral absorption range of the device,but also increases the charge extraction ability of the device and the dissociation efficiency of excitons,compared with binary organic solar cell,the PCE of the ternary organic solar cell increases from 10.09% to 11.18%.The experimental results show that N2200 enhances the crystallization of ternary blendfilms,increases the phase separation degree of donor and acceptor,and optimizes the interface structure of ternary blend films.However,with the proportion of N2200 continues to increase,the PCE gradually decreases,which is due to the degree of phase separation is too large,which has a negative impact on the exciton dissociation and charge transport.