The Influence Of Chemical-Physical Properties Of Organic Donors/Acceptors On Their Organic Photovoltaic Performance

Organic conjugated semiconductor materials are widely used in the field of organic electronics due to their advantages such as good light absorption coefficient,simple raw material preparation,and portable products.Organic photovoltaics is a new type of clean energy technology.Its device structure is characterized by the use of organic semiconductor materials with electron donor and acceptor characteristics in the active layer.In this dissertation,a series of polymer donors and non-fullerene small molecule receptors are constructed around thienopyridine(TI)and they are tested.The specific research contents are as follows:Based on the fact that our research group has synthesized P-IR,an asymmetric structure PCE has reached 5.83%.At the same time,its open circuit voltage VOC is 0.69 V,short circuit current JSC is 13.92 m A·cm-2,and fill factor FF is 61.8%.An isotactic polymer donor structure is designed to obtain a polymer PR with a PCE of 1.01%.At the same time,the open circuit voltage VOC is 0.59 V,the short circuit current Jsc is 0.61 m A·cm-2,and the fill factor FF is 2.81%.We have explored the reasons for the high efficiency of non-isotactic polymers over isotactic polymers through a series of theoretical calculations,TEM tests,AFM tests,etc.Annealing affects its morphology and causes its accumulation to affect performance.Thienopyridine(TI)and 4,7-dibromobenzothiadiazole(BT)have been used to synthesize the final monomer using hydrocarbon activation.Polymer PTITT and polymer PTIBDT are obtained by using thiophene and benzodithiophene(BDT).We have found through UV and electrochemical tests that PTITT and PTIBDT have a broad absorption in the range of 300-800 nm.The HOMO energy levels are-5.25 e V,-5.16 e V,and the energy gaps are 1.5 e V,1.41 e V.The polymer PTIBDT has no obvious P-type semiconductor characteristics and has certain N-type semiconductor characteristics.The PTITT has a mobility of 10-4 cm2·V–1 s–1 order of magnitude.The PCE of the photovoltaic performance polymer PTIBDT reaches 0.48%,while at the same time its open circuit voltage VOC is 0.61 V,the short circuit current JSC was 2.9 m A·cm-2,and the fill factor FF is 26.6%.TI units are coupled using thiophene-terminated TI coupling with benzene ring end TI and one more thiophene ring and one thiophene ring to make two non-fullerene acceptor small molecules SM1,SM2.We investigates the UV and electrochemical tests and find that SM1 and SM2 in the film have a broad absorption at 300-800 nm.Their HOMO energy levels are-5.96 e V,-5.45 e V,respectively,and their energy gaps are 1.66 e V,1.15 e V,PV performance is further explored.