Interface Engineering Of PM6:Y6 Non-fullerene Organic Solar Cells

Organic solar cell（OSCs）has attracted great attention and extensive research because of its light weight,flexibility and potential fabrication by roll-to-roll techniques in mass production.With the development of photoactive materials and interface materials,the power conversion efficiency（PCE）of non-fullerene OSCs（NF-OSCs）with conventional structure has exceeded 18%.However,due to the high acidity and hydrophilicity of PEDOT:PSS in the OSCs in conventional configuration,the long-term stability of the OSCs in conventional configuration is a key problem.Because of its vertical phase separation and excellent long-term stability,OSCs in inverted configuration has get great interest.Outstanding research to improving the PCE,stability and commercial production of OSCs in inverted configuration through interface engineering of NF-OSCs by select proper cathode interface layers（CILs）.In the thesis,the CIL material zinc oxide（ZnO）is selected,that is widely used in the inverted NF-OSCs.Through the modification and passivation of ZnO,efficient NF-OSCs are fabricated and its stability is improved too.On this basis,CIL materials insensitive to modification ratio were prepared.The main researches of the thesis include:（1）6-ACA modified ZnO（6-ACA-ZnO）materials were prepared by introducing small organic molecule 6-aminocaproic acid（6-ACA）into sol-gel CIL.When 6-ACA-ZnO is used as the CIL of PM6:Y6-based NF-OSCs,a device with a PCE of 16.50%（average PCE of16.35%）is fabricated,which is much higher than 15.31%of on the pristine ZnO based devices.The application of 6-ACA-ZnO in fullerene OSCs,ternary OSCs and other NF-OSCs also shows excellent device performance.The work function of surface decreases significantly,which effectively reduces interface energy barrier and enhances the carrier transport.At the same time,6-ACA passivated the surface defects of ZnO and inhibited the carrier recombination.These are the reasons for the improvement of J_SC,FF and stability in the 6-ACA-ZnO based devices.In addition,NF-OSCs devices are insensitive to the modification ratio of 6-ACA-ZnO and are easy to be in a large scale.The results show that6-ACA-ZnO can effectively improve the performance and stability of NF-OSCs and is a good CIL for inverted OSCs in general.（2）small molecular crosslinker DL-lipoic acid（DLTA）is easy to cross-link self-polymerization.Using DLTA modified sol-gel ZnO（DLTA-ZnO）as the CIL,PM6:Y6-based NF-OSCs with a PCE of 16.62%（average PCE of 16.50%）is prepared.The PCE is much higher than 15.40%of devices based on pristine ZnO.DLTA significantly reduces the work function of ZnO surface that promotes electron transport and effectively blocks holes,passivates oxygen vacancy defects on the surface of DLTA-ZnO,and suppresses carrier recombination.Through the study of the electrical properties and film morphology of XPS,the reasons for the improvement of J_SC,FF and stability in OSCs are analyzed.The rough surface of DLTA-ZnO film can increase the contact area between CIL and active layer,which is beneficial to carrier evacuation.In addition,DLTA-ZnO makes the hydrophobic active layer films more hydrophobic and improves the interfacial stability.NF-OSCs based on DLTA-ZnO shows excellent stability.The results show that DLTA-ZnO can effectively improve the performance and stability of NF-OSCs and is a good CIL for inverted OSCs.