Theoretical Study On The Transport Properties Of Typical Organic Charge Carrier Transporting Materials

The investigation of novel optoelectronic materials has been prompted by thepursuit of the high performance optical and electronic devices, such as light-emittingdiodes （LED）, field effect transistors （FET）, photovoltaic cells （PV）, and so on.Compared with inorganic materials, organic and organometallic materials haveconsidered as remarkable materials, due to the varieties of molecular structures andthe flexibilities of molecular packings. Recently, a great deal of effort has beeninvested in the theoretical study on typical photoelectric material systems tounderstand the experimental phenomenon and design new photoelectric materials. Inthis paper, we systematically investigated complicated relations among molecularstructure, packings and the mobility in depth by Marcus theory and band modelcalculation. We hope to provide theoretical supports for understandings andawarenesses of organic optoelectronic materials. Our work mainly includes fouraspects as follows.1. The structural, electronic and charge transport properties of thePt（CN_tBu）₂（CN）₂based material were systematically investigated by DFT andfirst-principle band-structure calculations. The calculation results indicate thatPt（CN_tBu）₂（CN）₂nanowires display ambipolar transporting feature with hole mobilityhigher than electron mobility. The intermolecular Pt Pt interactions provide the holestransport channel and the electron transfer is mainly along the CN groups.2. The electronic properties of compound1,13,14-Triazadibenz [a, j] anthracene（Tdba） are investigated by UV-visspectroscopy, cyclic voltammetry, time of flightphotoconductivity, X-ray crystallography, and density functional theory. Theexperimental and calculated results suggest ambipolar charge transfer character ofTdba. We find that there are small discrepancies between the hole and electrontransfer integrals and the smaller intramolecular hole reorganization energiesdetermine the bigger hole transport properties.3. The charge transport properties of （ppy）₂Ir（dipba） and its derivatives were investigated by Marcus electron transfer theory, focusing on intramolecularreorganization energy, intermolecular transfer integral, and hopping rate. The mobilitycalculation results demonstrated that these studied Ir compounds are efficientelectron-transfer materials. The molecular packings play a decisive role in the electrontransport properties and that in （Fppy）₂Ir（dipba）,（ppy）₂Ir（dipcca） and Ir（Fppy）₂（tipg）is propitious to electron transport leading to increased mobilities. In addition,Ir（Fppy）₂（tipg） with the smallestΔE（S₁-T₁） have the biggest radiative decay rateconstants.4. The charge carrier mobilties of N,N-di（n-butyl）quinacridone （DBQA） andN,N-di（n-fluorine）quinacridone （DFQA） derivatives were investigated in theory. It isfound that the molecular packings play a decisive role in the transport properties.