Synthesis And Application Of Advanced Organic Optoelectronic Materials

With the continuously development of organic optoelectronic materials,the types of organic materials are also increasing,and different photoelectric materials are invented according to their different application purpose.For organic solar cells,finding good matched donor-acceptor optoelectronic materials is able to obtain high conversion efficiency.For photodetectors,sometimes we don not need materials with high conversion efficiency but orther features such as rapid response.Similarly,in order to be future widely using in commercials,high yields and simplities of material synthesis are prerequisite.The research in this experiment is mainly to simplify the synthetic route of high-performance optoelectronic materials,and to prepare optoelectronic devices based on the synthesized new materials.Based on the existing optoelectronic devices,provide new ideas and new development.This research thesis is mainly divided into two parts,one is the application research of organic photovoltaic materials in solar cells;the other is the investigation in photodetectors.The specific study is as follows.(1)Investigation the Synthesis of Organic Optoelectronic Materials and Its Application in Solar Cells.(a)Here,our study presents a simply synthesis proposal for perylene monoimides with traditional wet solution reaction in one reaction from commercially available perylene tetraanhydride and our synthesis strategy got moderate yield.Their dimmer or ethynylene or butadiynylene bridged perylene derivatives were then developed smoothly.The work expanded the structural diversity of these dye molecules to a multifunctional class of n-type semiconductor materials.The high LUMO level(-3.83?-3.96 e V)reduced the energy loss in light of traditonal fullerene PC₇₁BM(LUMO=-4.04 e V).Using these compounds as non-fullerene electron acceptors constructs the inverted solar cells,the power conversion efficiency is up to1.45%for wide band gap polymer donor,the device is semitransparent with an ultrathin active layer thickness of 30 nm.(b)Three acetylenes bridged perylene mono-imide dimers as the second non-fullerene acceptor component used for efficient ternary solar cells.The molecular aggregation behavior of the host donor and acceptor was greatly affected when active layer film prepared by solution method.15%weight ratio of the third annexing agents adjusted the active layer properties all-sided including enhanced light absorption,improved morphology,and facilitating excitons splitting,transporting,and collection.Greatly increase in V_oc,J_sc and fill factor(FF)was observed consequently,a power conversion efficiencies(PCE)increased to9.77%was obtained comparing to that of 8.35%of the control binary device.(c)Interfacial modification is the dominating method to optimize electrode properties.Two easy synthesized perylene-monoimide(PMI)derived organic phosphonium bromide was found interestingly valuable applied as cathode interlayer(CIL)in bulk heterojunction(BHJ)organic solar cells(OSCs).Using the PBDB-T:ITIC blend active layer in inverted device structure,the photovoltaic performance was greatly improvement from the power conversion efficiency(PCE)9.49%of the referenced device which is without phosphonium CIL to PCE 10.42%with PMI-triphenyl-phosphonium bromide(PMI-TPP)and PCE 9.87%with PMI-trimethoxylphenylphosphonium bromide(PMI-TMOPP)as CIL.(2)Study on the Photoresponse Characteristics of Organic PhotodetectorsThree small molecules furnished with a planar core,(5,6-bis(octyloxy)benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(thiophene-5,2-diyl),and two wings,thieno[3,2-b]indole or carbazoles,were synthesized and used as sensing layer to make photo-detectors.The devices can detect photons at a wavelength band of 300-700 nm and exhibit a sensitive photo-response under on/off modulation.Near UV(405 nm)and visible(532 nm)laser beam were the light source in this work.The corrected responsivity reached up to 498 m A W^-1 at 532 nm and 411 m A W^-1 at 405 nm.Laser induced photo-current escalation was observed and investigated.For longer molecules,the photo-current was easy to be constant than the shorter reference counterpart.This special photo response mechanism was studied by alternating current impedance spectroscopy(IS)measurements and X-ray diffraction(XRD)exprements.Possible relations between molecular weight and various figures of merit for photo detectors was discussed.