Design And Exploration Of Highly Efficient Thermally Activated Delayed Flourescence Materials

Organic conjugate photoelectric materials have been widely studied due to its unique photophysical properties,of which TADF molecules are widely studied for high exciton utilization and low costs.Therefore,it is very important to explore and design new TADF materials for high performance of synthetic organic photoelectric materials.Given this,a serious of studies were carried out to explore the properties of the TADF molecules based on the First Principle/ ab initio,density functional theory(DFT)and time-dependent DFT(TDDFT),including the study on the photoelectric properties of TADF materials,the theoretical study of the intersystem crossing rates of TADF materials and the design of new highly efficient TADF materials.The main contents of the present work are summarized as follows:Six different ways were carried out to explore the spin-orbit coupling between the S1 and T1/T2 states of the TADF molecules,theoretical calculations were employed including the transition configuration analysis,natural transition orbital(NTO)analysis as well as the similarity analysis(s H/s L)based on S0/T1 geometry and the SOC calculation in Dalton program.All of them were not only proven to be good ways to predict the channels but also provide methods which can semiquantitatively indicate the SOC between S1 and T1/T2.Relevant work is of great significance to the design of new TADF materials.The exploration of intersystem crossing rates of TADF molecules including the intersystem crossing(ISC),reversed intersystem crossing(RISC),the driving force between the initial and final states(?G),Marcus reorganization energy,solvent reorganization energy and intersystem crossing rates were carried out for the relevant TADF molecules.As a result,the calculated data were basically in line with the experimental ones,indicating the correction of the methods had been used which provides a unique way to study the intersystem/reverse intersystem rates of the TADF molecules thus showing a significant rule in indicating the properties of TADF molecules.Design strategies for highly efficient TADF molecules based on 4CzTPN had been studied here.Basic properties such as the frontier molecular orbital analysis,natural transition orbital(NTO)analysis,singlet-triplet energy splittings,spin-orbit coupling(SOC),intersystem crossing rates(kisc)and many other parameters were studies here to indicate the properties of the investigated compounds thus screening out the best one,which is of great significance for the design of high-efficiency TADF materials.