| Because of its high porosity and high conductivity,conductive metal organic frame(MOFs)can be used in the fields of batteries,supercapacitors,electrocatalysis and photoelectric sensors.A class of conductive MOFs of two-dimensional planar structure consist of conjugated organic ligands connected by planar 4-coordination metal nodes.The layers form 3D structure via π-π stacking to leave 1D channels in the perpendicular direction.This MOF series is of significant interest,but how the metal nodes are involved in electrical conductivity is still unknown.To investigate the possible function of metal connecting nodes in the conductive MOFs,we changed the connecting metal nodes to non-transition metals in hope to uncover the function of the metal centers in a comparative study with MOFs built from the same ligand using transition metals.In the second chapter of this paper,the conductive MOF-Gd/Eu-HHTP(2,3,6,7,10,11-Hexahydroxytriphenylene)of regular octahedron and hexahedron crystal were synthesized,and the conductivity was tested.It is proved that the conductivity of hexahedron(10-5 S cm-1)is 2～3 orders of magnitude higher than that of regular octahedron phase(10-7～10-8 S cm-1).The Sc/Mg-HHTP of the hexahedron phase were also synthesized,and its conductivity(10-5 S cm-1)and the Gd/Eu-HHTP of the hexagonal prisms phase were in the same order of magnitude,which were comparable to reported value for Cu-HHTP(10-4 S cm-1).The retention of luminescence of Eu-HHTP proved that the f-electron in Eu does not participate in forming the conduction band of the MOF.Thin two-dimensional conductive MOFs of large area and were synthesized by using the water-pentane interface.All the evidences point to one conclusion:the conductivity of these MOFs mainly come from π-π stacked organic linkers in the perpendicular direction.Based these understandings,the organic linkers without the metal-connecting nodes should form organic semiconductors.Organic semiconductor is widely used in organic light-emitting diodes(OLEDs),organic photovoltaic devices(OPVs)and OFETs.There are many electronic devices with curved screen made of OLEDs.Because of its low cost,flexibility and portability,organic semiconductors make it possible to make wearable microelectronic devices in the future.Field effect transistors(FETs)based on two-dimensional materials are not affected by the short channel effect(SCEs)and can improve the degree of micro-integration of electronic devices.FETs based on two-dimensional conductive MOFs and two-dimensional organic semiconductor can be further modified to improve performance.The preparation of two-dimensional conductive MOFs and two-dimensional organic semiconductors which are large-area,easy to transfer,uniform and of low thickness is the starting point for the subsequent assembly of FETs in functional electronic equipment.In the third chapter of the paper,we used the LB method in synthesizing two-dimensional 2,3,6,7,10,11-hexaaminotriphenylene(HATP)polymer film of large area(cm2)at water-air interface,which are thin(5.7 nm),uniform and easy to transfer.The HATP polymerization and the formation of polymer film were proved by infrared(IR)absorption spectroscopy.Through comparison experiment of preparing the sample under N2 atmosphere in a glove box,we found that oxygen is essential for HATP polymer film formation,and it was antioxidant in the polymerization reaction.Then the membrane was transferred to the SiO2/Si substrate and coated with a gold electrode to make an FET.The photoelectric properties of the membrane were tested.The results showed that the two-dimensional HATP polymer film exhibited properties of p-type semiconductor,and the conductivity was up to 0.91 S cm-1 with an on-off ratio up to 103 and optical response(980nm)up to 160 mA W-1. |
PDF Full Text Request