N-type Organic Donor-acceptor Complexes: Preparation And Electronic Property Investigation

Organic charge transfer complexes are constructed by electron donor and electron acceptor,in which noncovalent interactions,consisting of hydrogen bonding,π-πstacking,electrostatic interaction,and metal ligand interactions,are regarded as the main driving forces to these multi-component framework building to form highly ordered super-molecular stackings.They have received abundant attentions since last decade,due to their unique advantages in charge transporting,luminescence,nonlinear optics,photoelectric conversion,and external stimuli response for the application prospects in the fields of medicine,electronics,photonics,luminescence,sensors,molecular electronics,etc.As the active semiconducting layer in organic field effect transistors,organic charge transfer complexes by integrating multiple components are not limited into the electrical features of the parent components,and show more tunable characteristics,so this calss provides a new approach for the design of next-generation semiconductor materials.Generally,the development of new semiconductor materials requires complicated synthesizing steps.Compared to the single-component compound,cocrystalizing can utilize the existing materials even with poor electrical performance to desired properties（n-type or ambipolar transporting）destroy by orientation rearrangemt to realize high-orderly close stacking.The polymorphism of charge transfer complexes is also of great role in the structure-property relationship investigation,and enables us new pathway for the development of high performance and multifunctional organic field effect transistors.This thesis focuses on the preparation and polymorphic regulation of novel organic donor-acceptor complexes,and the main contents are as follows:1:Organic charge transfer complex based on perylene and tetracyanodiazafluoren（TCAF）were successfully prepared trough a simple solution assembly method,and polymorphisms were found through preparation tailoring.Forα-phase cocrystal from homogenous neclation growth,the1:1 mixed stacking columns are divided into two manners:zig-zag lines with a slipping angle of 61°and typical mixed alignments with a ratio of 2:1.As for theβ-cocrystal with heterogenous neclation dominating,TCAF molecules were parallel to each other in the fixed linear mixed stacking dimension way with efficient overlapping.Furthermore,through duplicate solution re-dip-casting treatment,complete phase transition occurred fromα-phase toβ-phase micro-cocrystals.Devices based onα-phase micrococrystal exhibited electron-transporting feature with the electron mobility of 0.06cm² V^-1s^-1,while the maximumμ_e extracted from the saturated region was up to 0.88cm²V^-1s^-1 forβ-phase microcrystals.Molecular orbital splitting method showsβ-phase crystals possess higher transfer integrals,the significant shift for effective carrier transfer integrals are supposed to result from the distinct hetero-molecular overlaps,due to homogeneous or heterogeneous nucleation engineering.2:In order to exploit the cocrystal systems,coronene-TCAF cocrystals have been prepared via the liquid-liquid interfacial precipitation（LLIP）method using coronene as the electron donor and TCAF as the electron acceptor,which possessed a 1:1 mixed structure,withπ-πdistance value of3.367?.However,both donor and acceptor molecules are disordered,hampering effective charge carrier transport.Coronene-TCAF needle-shaped microcrystals obtained by the drop-casting method based organic field effect transistors（OFET）with a top contact/bottom gate geometry exhibited electron transporting feature with the electron mobility of 6.08×10^-4cm²V^-1s^-1,which is much lower than perylene-TCAF cocrystal.