Application Of Quinacridone Derivatives As Cathode Interlayer In Nonfullerene Organic Solar Cells

Organic solar cells（OSCs）are green energy technologies with great development prospects,which have great advantages in low cost,light weight,mechanical flexibility,semitransparency and large-area printing.In recent years,OSCs have developed rapidly,and the power conversion efficiency（PCE）of single-junction OSCs has exceeded 19%.This is related to the synthesis of new materials,the optimization of device structures,the regulation of active layer morphology,and the modification of interlayers.Among them,adding cathode interlayer（CIL）between the cathode and the active layer can reduce the electron extraction potential barrier,improve the ohmic contact between the active layer and the cathode,and then improve the device performance.With the commercialization of OSCs continues to advance,and the development of cathode interlayer materials with high conductivity and thick film processing has become one of the important challenges for the commercialization of OSCs.The development of cathode interlayer materials with high conductivity and thick film fabrication is one of the important challenges in the industrial production of OSCs.Although water/alcohol-soluble cathode interlayer materials can effectively improve the PCE of OSCs and are easy to process,most of them have low electrical conductivity,leading to their low thickness as CILs,which cannot meet the needs of large-area production.Therefore,it is very important to develop cathode interlayer materials with high conductivity and thick film processing.In this paper,the quinacridone derivative DCNQA-Py Br was used as the cathode interlayer to obtain high device efficiency in a wide thickness range of 5-88 nm,and the effects of quinacridone derivatives as CILs on the device performance of non-fullerene organic solar cells（NF-OSCs）were also investigated.To further improve the device efficiency,we use acridine orange base（AOB）n-doped DCNQA-Py Br and investigated the effect of doping on the device performance of OSCs.In the first chapter,the introduction part mainly introduces the development history,working principle,main parameters of OSCs device performance,the research progress of OSCs active layer and interlayer materials,and the research progress of OSCs doping.In the second chapter,the effects of quinacridone derivatives（DCNQA-Py Br and QA-Py Br）as CILs on the device performance of NF-OSCs have been investigated.We made NF-OSCs devices with DCNQA-Py Br and QA-Py Br as CILs and PBDBT:ITIC and PM6:Y6 as active layers.In OSCs with PM6:Y6 as the active layer,the PCE is15.52%when the thickness of DCNQA-Py Br is 18 nm,and when the thickness of DCNQA-Py Br reach 88 nm,PCE is 12.88%.DCNQA-Py Br exhibits great thickness tolerance,is suitable for realizing large-area roll-to-roll（R2R）printing in industry.Capacitance-voltage（C-V）curve,photocurrent density-effictive voltage(J_ph-V_eff)curve,dark current density-voltage(J_dark-V)curve,variation curves of short-circuit current density(J_SC)and open-circuit voltage(V_OC)on light intensity and electron mobility test results shown that the containing DCNQA-Py Br as CIL has higher built-in potential and carrier concentration,higher exciton dissociation and charge collection ability,lower carrier recombination and better electron transport capability than QA-Py Br as CIL.Conductivity tests show that DCNQA-Py Br has higher conductivity than QA-Py Br.It can be found that solid-state DCNQA-Py Br has stronger self-doping behavior than QA-Py Br by electron paramagnetic resonance（EPR）.In addition,atomic force microscopy（AFM）imaging shows that the surface roughness（RMS）of the active layer decreases with the increase of the thickness of DCNQA-Py Br,forming a relatively smooth surface morphology.In the third chapter,The effect of AOB doped quinacridone derivatives as CILs on the performance of OSCs was investigated.We made OSCs devices with DCNQA-Py Br:AOB as CILs.When the cathode is Ag,the PCE of OSCs whose active layer is PM6:Y6 can reach 16.30%.C-V curves,J_ph-V_eff curves,J_dark-V curves,and the variation curves of J_SC and V_OC with light intensity show that AOB doping can improve the built-in potential,carrier concentration,excitons dissociation and charge collection efficiency of the device,reducing carrier recombination.Electron mobility measurements indicate that AOB-doped DCNQA-Py Br enhances the electron mobility of the device.Conductivity measurements show that AOB doping can enhance the conductivity of DCNQA-Py Br.The EPR results indicated that charge transfer occurred between AOB and DCNQA-Py Br.AFM results show that AOB doping does not destroy the surface morphology of the active layer,and even slightly improves it.