Morphology Regulation And Interfacial Optimization In Non-Fullerene Polymer Solar Cells

At present,energy issues are increasingly prominent.As a new renewable energy technology,an alternative energy source of fossil fuel,polymer solar cells(PSCs)have attracted widespread attention from people all over the world with its unique advantages of low cost,light weight,flexibility,roll-to-roll large area preparation,etc.Compared with fullerene acceptors,non-fullerene acceptors have the characteristics of easy to adjust optical and electronic properties,better solubility,higher absorption coefficient,and easier synthesis.Therefore,the PSCs with non-fullerene n-type organic molecules as acceptor(non-fullerene PSCs)have attracted great attention in recent years.So far,the highest power conversion efficiency(PCE)of single-junction non-fullerene PSCs has exceeded 15%.In this paper,we investigated the effects of the active layer morphology and the cathode modification layer on the performance of the non-fullerene PSCs.The main research results are as follows.1.We prepared non-fullerene PSCs based on PTZ1:IT-4F as active layer.The polymer donor PTZ1 has a strong absorption in the short wavelength of 300-650 nm with an optical band-gap of 1.97 eV,which posseses complementary absorption with that of the acceptor IT-4F with absorption in the wavelength range of 550-850 nm and an optical band gap of 1.67 eV.After 0.5%NMP additive treatment,the morphology of the active layer was regulated and the short-circuit current density(Jsc)and fill factor(FF)of the device were improved,thus achieved a high PCE of 8.8%.2.Although ZnO is an efficient electron transport layer(ETL),it has many defects.In this study,we investigated the effects of ZnO and Glycine modified ZnO(ZnO/Gly)ETLs on the photovoltaic performance of the inverted PSCs.The device based on PM6:IT-4F with ZnO/Gly as ETL exhibited a remarkably enhanced PCE of 14.0%relative to 12.9%for the control device with ZnO ETL,indicating?9%increase of the PCE with the simple molecular modification of the ETL.This is because Gly decreased the surface defects,reduced the surface work function and changed the surface energy of ZnO.Therefore,the Jsc and FF were significantly enhanced,thus the PCE is improved.In addition,the method can be successfully applied to other non-fullerene and fullerene inverted PSCs.This indicates that the modification of ZnO ETL by Gly is a simple,green and effective method for improving the photovoltaic performance of the inverted PSCs.