Synthesis And Photovoltaic Properties Of N-Type Cathode Interface Materials For Organic Solar Cells

In order to solve the problem of fossil energy shortage,researchers began to explore new energy sources.As an inexhaustible renewable energy,solar energy has attracted extensive attention of researchers.And,the photoelectric conversion technology can directly converts solar energy into electric energy.Compared with inorganic solar cells,organic solar cells have the advantages of low temperature solution processing,low cost and light quality.And,interface materials are often used to improve the device performance.N-type cathode interface material has the advantage of being used in large area device fabrication because of its excellent electronic transport properties.This dissertation focuses on the design and synthesis of n-type cathode interface material and their properties in OSCs.In the second chapter,we synthesized two interfacial materials,TEH-ZnP-ET-TAZ-Br and FN-ET-TAZ-Br,by connecting triazine units with quaternary ammonia polar groups with porphyrin rings and aminofluorene,respectively.The PTB7:PC₇₁BM-based devices with FN-ET-TAZ-Br and TEH-ZnP-ET-TAZ-Br as cathode interface materials exhibit photoelectric conversion efficiency of 6.82%and 7.87%,respectively,which is obviously higher than that of the device without interface layer?4.17%?.The results show that enlargated conjugation rings can coordinate the electronic transport performance of molecules,improve the charge transfer performance,therefore improve the performance of devices.In the third chapter,we synthesized two interfacial materials TEHZnP-ENI-Br and TEHZnP-ENDI-Br by linking the porphyrin ring with Naphthalimide and Naphthalenetetracarboxdiimide with polar quaternary amino groups via alkyne bridges.The PTB7:PC₇₁BM-based devices with TEHZnP-ENI-Br and TEHZnP-ENI-Br as cathode interface materials exhibit photoelectric conversion efficiency of 8.09%and 7.05%,respectively.The results show that the strong electron-deficient ability of the conjugated main chain and the electron-donating ability of the electron-rich groups determine the interface performance together,thus affecting the performance of the device.In the fourth chapter,we synthesized two small molecule cathode interface materials NDI-Phen-Br₄ and PDI-Phen-Br₄ by connecting the phenanthroline unit with the inner polar group of the ring with NDI and PDI,respectively.The PTB7:PC₇₁BM-based devices with NDI-Phen-Br₄ and PDI-Phen-Br₄ as cathode interface materials exhibit photoelectric conversion efficiency of 6.10%and 6.68%,respectively.On the other hand,In PBDB-T:IT-M-based devices,the efficiency of devices using PDI-Phen-Br₄/LiF as cathode interfaces is 11.1%,which is higher than that using PFNBr/LiF as the interface.