Study On Effect Of Molecular Arrangement On Spin Effect In Organic Cocrystals

In recent years,organic semiconductor materials because of their light weight,good flexibility,easy production,environmental protection and other advantages,has become a research hotspot in many fields such as organic field effect transistor,organic solar cells,organic light-emitting diodes and so on.With the growing maturity of technology,organic semiconductor devices in People’s Daily production and life has begun to make a mark,in many fields because of its superior performance,has gradually become the current market favorite.In order to meet the diversified requirements of application scenarios,people want to get organic materials with richer functions and wider application scope.In this context,cocrystal engineering,as the most simple and effective method to integrate many advantages of organic materials,has become the most effective performance improvement scheme of organic semiconductor materials,and has gradually developed into an independent comprehensive discipline.As a new subject,organic electronic spin has attracted the attention of many researchers.Reasonable design of organic electronic spin materials will inject powerful power into human production and life.However,compared with inorganic semiconductor,organic cocrystal has more complex composition and more diversified molecular interactions,which makes its physical properties more abundant and difficult to achieve effective human control.However,when the crystal composition is the same,the change of the relative arrangement of molecules is usually accompanied by the change of the intermolecular interaction,which leads to the different electron spin effects in the crystal.There are many ways to change the relative arrangement of the donor and acceptor molecules in the cocrystal.The molecules are usually arranged differently in the crystal due to the different proportion of donor and acceptor input or the different choice of solvent during the growth process.And the movement of molecules within the crystal under external stimuli can also change the way they arrange themselves.With the deepening of the research on organic materials,people hope to realize directional synthesis and control of organic materials by understanding the complex physical properties of organic cocrystal materials.Therefore,the changes in the physical properties without changing the donor and accepter components provide a reliable basis for us to further understand the regulation methods of electron spin in cocrystals.In this paper,organic charge transfer crystals Perylene-TCNB-THF and Perylene-TCNQ were prepared by solution volatilization method respectively,and the molecular arrangement in the organic cocrystal was adjusted by polarized light rotation and different solvents respectively,so as to change the crystal structure and further explore the influence on the organic spin effect.The details are as follows:1.Perylene-TCNB-THF and Perylene-TCNB organic cocrystals were prepared by solution method with tetrahydrofuran(THF)as solvent,and their crystal structures were obtained by single crystal XRD.There are many kinds of charge transfer interactions in the complex structure of ternary crystal and the influence of molecular arrangement changes on the crystal structure and spin properties.We discuss the changes of molecular arrangement of multi-component organic cocrystal under external conditions.The movement of organic molecules under polarized light;Crystal structure before and after molecular movement;Changes in electron spin and optical properties within a crystal.Based on the above research,reasonable conjecture is given for the interaction between molecules in the organic eutectic and a solution is given for the external stimulus control of organic crystal.This experiment provides a solution for designing crystal properties reasonably through molecular arrangement By studying the external polarized light excitation of molecular motion in ternary crystal,we found that the polarized laser can adjust the molecular motion in solid organic crystal at room temperature,thus changing the electronic structure of the crystal.The change of the electronic structure of the crystal will further affect its spin and optical properties.But when the temperature drops to 77 K,the molecules in the ternary charge transfer crystal will be fixed,and the external polarized light cannot adjust the motion of the molecules.In addition,when the laser illumination is converted from linearly polarized light to circularly polarized light,the dependence of molecular motion on spin and optical properties is obviously different.Furthermore,the crystal band structure was calculated and analyzed by DFT theory,and the change of crystal band before and after polarized light stimulation was compared.Perethylene-TCNB-THF crystal is excited by 405 nm and 532 nm laser respectively,and the fluorescence spectra of the crystal show red shift with increasing illumination time.2.Perylene-TCNQ(1:1)and Perylene-TCNQ(3:1)organic cocrystal were prepared by toluene and benzene in different solvents,respectively.Through the above-mentioned two kinds of different ratio of crystal XRD crystal structure analysis can see crystals in a 1:1 ratio to receptors for-DADADA-configuration,3:1 ratio for-DDADDA-when arranged,two kinds of crystal,though the same color to the naked eye,but can be found in the fluorescence spectrum test luminous position is different,both P3T1 type crystal light position relatively P1T1 red-shift,suggesting that P3T1 type crystal to stronger interaction between receptor,between HOMO and LUOM band gap smaller.The influence of molecular configuration on the spin of electron-hole in crystal was studied by measuring the dielectric constant under different conditions.The magnetic field can adjust the ratio of single states and triplet states in P3T1 crystal,increase the ratio of tristates in P3T1 crystal,and enhance the dipole polarization.The dielectric constant of P3T1 crystal has obvious magnetic response.