Modification Of Interface Materials And Their Application In Polymer Solar Cells

Among various devices using solar energy,polymer solar cells?PSCs?have become the hot issues because of the low-cost,easy-processing and light weight.Currently,the photoelectric conversion efficiency?PCE?of the PSCs has reached 15%,but the PCE is far below the theoretical value originating from the limitations of existing technologies.There are two kinds of PSCs structures,including conventional polymer solar cells and inverted polymer solar cell.PCE and stability of both PSCs devices can be efficiently enhanced by the addition of interfacial modification layer,which leads to the study of interfacial modification materials.With high conductivity and light transmittance,PEDOT:PSS becomes one of the most common anode interface layers?AILs?whereas n-type semiconductor Zinc oxide?ZnO?is widely used as canode interface layers?CILs?.In this paper,the characteristics of the interface layers/organic active layer are regulated through the study of PEDOT:PSS and ZnO to improve the performance of PSCs devices.The specific contents are as follows:?1?We find that acid treatment,including trifluoroacetic acid?TFA?and oxymuriatic acid?HAuCl₄?,can arouse phase segregation of the conductive PEDOT and insulted PSS to modulate the chemical structure of PEDOT:PSS.The enhanced conductivity and work function?Wf?can be obtained.And oxymuriatic acid?HAuCl₄?modification can synthesizing Au nanoparticles?Au NPs?in the meanwhile.Therefore,the champion P3HT:PC₆₁BM based devices PCE reaches to 4.08%and in PTB7:ICBA based PSCs,we can obtain the best device performance with the PCE of 8.05%.?2?We successfully synthesized controllable ZnO nanoarrays?ZnO NRAs?by solution growth method,and Bi₂S₃ were coated on the ZnO NRAs through successive ionic layer adsorption and reaction method?SILAR?,after which the ZnO NRAs and ZnO NRAs/Bi₂S₃are applied as cathode interfacial layer?CILs?,respectively.Bi₂S₃ coated can increase ZnO crystallinity,lower the surface defects and increase the crystallinity of the active layer,the light absorption and exciton dissociation are thereby enhanced.Here,the best PCE of P3HT:PC₆₁BM based IPSCs is 3.57%when ZnO NRAs/Bi₂S₃ is used as CILs,and when this method is applied in PTB7:PC₇₁BM based IPSCs,the champion devices PCE is 6.35%.?3?We use n-type semiconductor Bi₂O₂S to manipulate ZnO NRAs surface for the first time,and the surface defects are significantly suppressed.The increased coupling of the treated ZnO NRAs/active layer is beneficial for the IPSCs when the pristine ZnO NRAs and ZnO/Bi₂O₂S are used as CILs.The results show that the series resistance is reduced and the crystallinity of the active layer is enhanced,so the highest P3HT:PC₆₁BM based PCE reaches to 3.61%and PCE of the ITIC:PDBD-T based IPSCs can be increased by 27.5%?from 7.76%to 9.89%?.?4?We have successfully fabricated nanoripple-like ZnO nanorod arrays?R-ZnO NRAs?and used narrow bandgap n-type semiconductor Bi₂OS₂ to modify the surface of R-ZnO NRAs for the first time.After Bi₂OS₂ modification,pristine R-ZnO NRAs and ZnO NRAs/Bi₂OS₂ are applied as CILs in IPSCs,and the results show that the reduced hydrophilicity of R-ZnO NRAs and the enhanced crystallinity of PTB7 lead to the enhanced light absorption and exciton dissociation.Compared to the untreated devices?PCE=5.51%?,the highest PCE of PTB7:PC₇₁BM based IPSCs can reach to 7.31%after Bi₂OS₂ modification,and PCE of ITIC:PBDB-T based IPSCs increased by 23.8%?from 8.03%to 9.94%?.