Study On The Performance Improvement Of Polymer Solar Cells Based On Interface Modification

Solar energy plays a vital role in alleviating environmental pollution and solving energy supply problems.Clean,renewable,low-cost and high-efficiency photovoltaic technology is the consistent goal of academia and industry.For solution processing,polymer solar cells with a wide range of materials,low cost,flexible preparation,and large area printing have received extensive attention and systematic research.According to reports in 2020,the power conversion efficiency of a single junction of polymer solar cells has exceeded 18%.However,we still need to continue to make efforts in terms of efficiency and stability to apply it to actual life and production.In this work,polymer solar cells based on double anode charge transport layer PEDOT:PSS/BCF and cathode charge transport layer zinc oxide doped HTAB were prepared respectively by selecting suitable interface modification materials and using reasonable experimental methods.Combining a series of photoelectric test methods,the influence of interface layer modification on the performance of polymer solar cells on the work function,mobility,conductivity,film roughness and wettability of the polymer solar cells is discussed in detail.This paper mainly includes the following two aspects:(1)Hole transport layer formed by stacking strong Lewis acid tris(pentafluorophenyl)borane(BCF)and PEDOT:PSS is applied to the fullerene-based polymer solar cell.The prepared device structure is ITO/PEDOT:PSS/BCF/PCDTBT:PC₇₁BM/Li F/Al.Firstly,using different concentrations of BCF isopropanol solution as a modified layer spin-coating on the PEDOT:PSS layer to explore the role of the BCF layer.The results show that the introduction of BCF layer can increase the surface work function of PEDOT:PSS,improve the energy level alignment problem with the active layer,increase the open circuit voltage and hole mobility at the same time.In addition,BCF solution spin-coated on the PEDOT:PSS film can smooth the surface of the PEDOT:PSS,reduce the roughness,passivate the surface traps,reduce the number of pinholes and the leakage current;improve the hydrophobicity of the PCDTBT:PC₇₁BM layer Compatibility with hydrophilic PEDOT:PSS layer.The efficiency increased 29.7%(from 5.889%to 7.642%)by using PEDOT:PSS/BCF in the PCDTBT:PC₇₁BM based positive cells compared with the original basic device.(2)Firstly,synthesize zinc oxide nanoparticles,then add broadband halide(1-hexyl)trimethylammonium bromide(HTAB)to the Zn O-NP dispersion to obtain an electron transport layer(Zn O:HTAB),and complete the structure as ITO/Zn O:HTAB/P3HT:PC₆₁BM/Mo O₃/Ag device preparation.The PCE of the device that P3HT:PC₆₁BM as the active layer has been increased from 3.48%to 4.44%,and the fill factor improved mostly significant(from 56.68%to 70.38%).According to the device characterization results,it can be concluded that the doping of HTAB reduced the work function of Zn O,enhanced built-in electric field,provided a stronger charge driving force and accelerated the extraction and transport of carriers.Compared with Zn O,Zn O:HTAB also has a significant increasing in electron mobility.Zn O doped HTAB improved the performance of the device,which is also reflected in the reduction of Zn O surface cracks after the film annealed,indicating that HTAB has the function of passivating surface traps and reducing leakage;At the same time,the introduction of HTAB changes the wettability of the surface of Zn O and improves the compatibility between electron transport layer and hydrophobic active layer.