Design,Synthesis Of Novel Conjugated Polymer Acceptors And Their Applications In All Polymer Solar Cells

To solve the world wide problems of environmental pollution and energy consumption,there have been lots of research to develop solar energy as the most promising new-generation green energy resourse.Organic solar cells have attached so much attention because of their unique advantages,such as light-weight,low-cost,flexibility and large area processing by rollto-roll printing method.All polymer solar cells(all-PSCs)consisting of polymer donors and polymer acceptors,have recently been developed extensively,due to their advantages over fullerene-PSCs: better light absorption in long-wavelength region,easy modification of chemical structure,better mechanical property and thermal stability.There have been many polymer donors,but the amount of polymer acceptors is relatively limited.Here,we designed and synthesized some series of novel polymer acceptor materials and investigated their application in all-PSCs,in order to improve the power conversion efficiency(PCE)of all-PSCs and provide the research foundation for the industrialization development of all-PSCs.In chapter two,we designed and synthesized a series of polymer acceptors besed on naphthalenediimide(NDI)and perylenediimide(PDI),containing an ethynyl moiety as the ?-bridge.Because of the ethynyl,the molecular geometry,planarity and crystallity have been improved.Therefore,the electron mobility of polymer acceptor materials was higher and active layer morphology was better,with the higher PCE.The space charge limited current,the fluorescence quenching spectrum and transient photocurrent were tested to investigate the charge carrier mobility,exciton quenching and charge carrier extraction.In chapter three,we desighed and synthesized novel polymer acceptors based on pyrrolopyrolidone(DPP)containing pyridine as the bridge.DPP-based acceptors had higher lowest unoccupied molecular orbital(LUMO)energy levels,which could make the open circuit voltage higher.DPP had strong electronic affiniry and good planarity.The pyridine bridge improved the planarity of DPP-based acceptors,which could make the electron mobility higher.We applied the DPP-based acceptors into all-PSCs,and got open circuit voltage over 1V and PCE over 2.5%.In chapter four,we introduced flexible chain into main chain as the linker beteen the rigid units,making the polymer with liquid crystal properties.By changing different rigid units,adjusting the lengths of flexible chains,we got stable liquid crystalline(LC)polymers.The LC polymers were applied into all-PSCs and the active layer morphology was adjusted by the LC properties.It would provide a simple method to optimize the active layer morphology of large area all-PSCs devices in the future.In chapter five,we tried to synthesize polymer acceptors via the tandom polymerization reaction.We have optimized the reaction time,temperature and solvent,and got the target polymer from the template precursors.Unfortunately,the monomers(dA-BT,dA-NDI)were unstable in the air,so the tandom polymerization reaction did not work for the monomers of polymer acceptors.However,tandom polymerization reaction provided a new direction for easy synthesis of polymer acceptors in the future industrialization of all-PSCs.