El Theoretical Study Of Carrier Transport Material

Organic semiconductor electroluminescence (called EL) phenomenon can be traced back to the earliest of 1963, which was reported first by Pope on the anthracene crystal electroluminescent devices,but the subsequent 20 years ,the high-voltage drive and the problem of low efficiency had not been solved,Organic EL of research has been in a stage of stagnation .Until 1987,KODAK company,sresearch staff with Tang and vanslyke used 8-Alq3 for the first time,access to the high efficiency of organic light-emitting diode (OLED),it started the new situation of the research for OLED.The vast majority of organic electroluminescent materials are organic semiconductors.In this paper quantum methods are used to discuss the infection of PPV-like electroluminescent polymer and NTCDA,s hole transmission rate with electron donating substitute and electrophilic substitute in order to design molecular rationally.The result shows that:PPV is a typical linear conjugate macromolecule,with the enlargement of n (degree of polymerization),the geometry structure of molecule keeps the same,generally,from The perspective of the molecule structure ,the difference of various values of dihedral angle is smaller than 0.1.The truck atom of the whole system has a superior coplanarity,and this character is beneficial to the electron delocalization.The increased number of the chain constitutional units doesn,t effect the coplanarity trend of truck atoms,besides,it is beneficial to the electron delocalization,and the hole hopping capability,the electron donating substitute leads to the decrease of the polymer energy gap,the Einstein shift of luminescent spectrum.With the reinforcement of ability ,the Einstein shift becomes more apparent. The electron donating substitute,such as the NH2,OCH3 substitute,increase the energylevel of HOMO orbit,while decrease the ionization potential,at the same time,the recognition energyλ,which is beneficial to the hole hopping transfer.This conclusion provides a theoretical accordance to choosing suitable and designing good hole hopping transfer material,which has a practical significance. -NO2,-CF3,-CN have the effect of electron conjugation ,the conjugation effect through the system is passed by the turn,such groups which have the effect of electronconjugation can reduce NTCDA,s electron density ,make the EA of NTCDA increase.-CN,-C6H6 can be formedπ-πconjugation with NTCDA which strengthen the capacity of electron transfer.