Device Fabrication And Performance Optimization Of High-performance Non-fullerene Polymer Solar Cells

Recently,non-fullerene polymer solar cells（NF-PSCs）have attracted great attention and achieved great success due to the non-fullerene small molecules have flourished as promising electron acceptor materials in PSCs.To date,much work has focused on promotion of device efficiency and made the NF-PSC commercialization.In this paper,we mainly focused on device fabrication and performance optimization of high-performance non-fullerene polymer solar cells,and discussed the relationship between the molecular structures of blend morphology in the active layer and the photovoltaic performance.Besides,based on the NF-PSCs,we fabricated and discussed the photovoltaic performance of large scale and flexible PSCs.The main results are as follows:1.An efficient NF-PSCs based on a polymer donor PM6 and a small molecule acceptor ITIC was developed.The PM6 possesses a large bandgap of 1.80 eV and a deep HOMO level of-5.50 eV.Moreover,PM6 shows a strong crystallinity and a dominant face on packing.After systematic optimization by using solvent additives and thermal annealing,The as-cast PM6:ITIC blended film shows strong and complementary absorption,relatively good charge transport,and appropriate phase separation scale.As a result,the PM6:ITIC-based PSCs obtained a power conversion efficiency（PCE）of 9.7%with a V_occ of up to 1.04 V,a J_scof 16.0 mA cm^-2and a FF of 58%after optimization,under the illumination of AM 1.5G,100 m W cm^-2.Notably,the energy loss(E_loss)of the PSCs is as low as 0.51 eV and the PSCs possesses a very smallΔE_HOMOof 0.10 eV.The PCE of 9.7%is one of the highest values in the reported literatures for the PSCs with a V_ocover 1.0 V and an E_lossless than 0.55 eV.2.To further improve the device efficiency,an efficient PSC based on a polymer donor PM6 and a narrow bandgap n-OS acceptor IDIC was developed.The IDIC exhibits a better crystallinity and a higher electron mobility than ITIC.Benefited from the energy levels matching and absorption complementary between polymer PM6 and IDIC,as a result,the PM6:IDIC-based PSCs without extra treatments displayed a high PCE of 11.9%with a V_ocof 0.97 V,J_scof 17.8 mA cm^-2and FF of 69%.Notably,the PCE value of 11.9%is the highest value reported in the literatures to date for the PSCs without extra treatments.Moreover,the device performances are insensitive to the active layer thickness（ca.95-255nm）and device area（0.20-0.81 cm²）with PCEs of over 11%.Besides,the PM6:IDIC-based flexible PSCs with a large device area of 1.25 cm² exhibit a high PCE of6.54%.These results imply that the PM6:IDIC blends is a promising candidate for the large scale roll-to-roll fabrication of high-performance PSCs.