Synthesis Of Small Molecule Organic Semiconductor Materials And Their Applications In Organic Solar Cells

Organic solar cells have outstanding advantages such as low cost,light weight,wide range of material sources,controllable molecular structure,relatively simple manufacturing process,and the production of large-area flexible devices.It has attracted considerable interests in the scientific research community and has great potential for pracitical importants.Based on the full investigation of the reported literature,this thesis has designed and synthesized organic small molecule donor materials and non-fullerene small molecule electron acceptor materials,and studied their thermal stability,photophysical properties,electrochemical properties and photovoltaic properties.The research work of this thesis mainly includes the following two parts:?1?Design and synthesize two conjugated A-D-A small molecules ITDCN and ITDCF,where asymmetric core indenothiophene were used as central electron-donating D unit,malononitrile,5,6-difluoro-1,1-dicyanomethylene-3-indanone were used as terminal acceptor unit,resepectively.The characterization of TGA,UV-vis and XRD proved that both molecules showed good thermal stability,strong absorption,excellent solubility and high crystallinity.The characterization results of the active layer films show that the introduction of ITDCN/ITDCF into the PDBD-T:PC71BM binary system can significantly improve hole mobility and electron mobility and make the two more balanced,which significantly improves the device fill factor.In the end,because the energy level and crystallinity are more suitable,As the energy level and crystallinity are more suitable,compared with the two components,the FF of the ternary system based on ITDCN is significantly improved?up to 20%?.The Voc of different proportion devices generally increases by 20-40 m V,and the highest reaches 0.83V.,The ultimate maximum efficiency increased by 24%.?2?Based on the structure of ADA,using the BDT unit as the center donor unit,a small molecule donor material DRCBDT2F was designed and synthesized.The small molecule's morphology,ultraviolet-visible absorption spectrum,electrochemical energy level,blend film morphology and charge mobility was studied.In the end,although DRCBDT2F has a high light absorption capacity,because DRCBDT2F and PC₇₁BM do not form a good nano-interpenetrating network structure phase separation in the active layer,the surface morphology of the active layer is too smooth and flat,resulting in serious carrier recombination and low PCE.