Preparation And Optoelectronic Application Of The Organic Donor-acceptor Complexes

Organic donor-acceptor complex is consisted of electron donor and electron acceptor with intermolecular non-covalent interactions,as a multiple-component supramolecular system.The innovative system with diversified physical and chemical properties have great potentials in the electronics and optoelectronics.As a novel research field,organic donor-acceptor complexes are developed as active elements in organic field-effect transistors?OFETs?due to their tunable energy levels and various packing modes in recent years,which not only fully utilize the existing organic semiconductors,but also avoid the complicated synthetic procedures.Compared to single component material,the more-complicated packing architecture of organic donor-acceptor complex is strongly influenced by chemical structure of original components and the preparation conditions,which will further affect the properties of their OFETs devices.Consequently,the adjustable properties of OFETs can be achived through the chemical modification of brand-new organic donor-acceptor complexes and the variation of growth conditions,providing a good insight into the relationship between the molecular packing patterns and the charge-transport properties.This thesis focuses on the design and assembly regulation of novel organic donor-acceptor complexes,and the main contents are as follows:1:Based on heteroatom substitution of the supramolecular design strategy,two nitrogen-containing derivatives of DCBz?DCPi,DCPa?were obtained by introducing nitrogen atoms into the middle benzene ring of 1,4-Di?9H-carbazol-9-yl?benzene?DCBz?.Using these three carbazole derivatives as electron donors and TCNQ as electron acceptors,three new organic donor-acceptor complexes with special stoichiometry and different stacking structures were prepared by a simple solution evaporation method(DCBz-TCNQ₂,DCPa-TCNQ₂ and DCPi-TCNQ_2.5),and their device performances were further studied.The test results show that the DCPa-TCNQ₂ microribbon devices exhibit n-type behavior with electron mobility of 0.008 cm² V^-1 s^-1 in ambient atmosphere,while the DCBz-TCNQ₂ and DCPi-TCNQ_2.5 nanowire devices show very poor ambipolar properties.According to the theoretical calculations,the DCPa-TCNQ₂ cocrystal revealed much higher electron transfer integrals and smaller intermolecular distance compared to the DCBz-TCNQ₂ and DCPi-TCNQ_2.5 complexes,leading to higher electron mobility of DCPa-TCNQ₂ microribbon devices.2:Two charge-transfer complex polymorphs based on perylene and 4,8-bis?dicyanomethylene?-4,8-dihydrobenzo[1,2-b:4,5-b?]-dithiophene?DTTCNQ?were successfully prepared trough a simple artificial nucleation-tailoring.With the help of thermodynamics/kinetics driving,?-phase and?-phase perylene-DTTCNQ cocrystals with different packing structures were separated obtained by the control of the homogeneous nucleation or heterogeneous nucleation process.The two kinds of polymorphic micro-nanocrystals exhibit significantly different semiconductor characteristics,and?-phase cocrystal displays ambipolar charge-transport characteristics and negligible photoresponsivity,while?-phase cocrystal exhibits higher n-type transporting performance and good photoresponsivity.3:Using coronene as the electron donor and HAT?CN?₆ as the electron acceptor,the coronene/HAT?CN?₆ cocrystals have been synthesized via the liquid-liquid interfacial precipitation?LLIP?method,which possess a mixed stacking structure with a stoichiometric ratio of 2:1.Due to the presence of DAD trimer and DD dimer along the stacking direction,both super-exchange electronic coupling and direct electronic coupling exist in the crystal structure,providing effective transport paths for holes.In contrast,the long distance between HAT?CN?₆ molecules along the stacking direction prohibit the electron transporting in the 2:1 mixed stacking structure.