用含时密度泛函方法研究和设计推拉结构的荧光分子

应用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)方法及连续极化模型研究了六种荧光材料分子基态和第一激发态的电子结构性质.这六种分子是:3-(二氰亚甲基)-5,5-二甲基-1-(3-9-(2-乙基-己基)-咔唑基]-乙烯基)环己烷(DCDHCC),DCDHCC2,3-(二氰亚甲基)-5,5-二甲基-1-(4-二苯基氨基-苯乙烯基)环己烷(DCDPC),DCDPC2,3-(二氰亚甲基)-5,5-二甲基-1-(4-9-咔唑基]-乙烯基)环己烷(DCDCC)和3-(二氰亚甲基)-5,5-二甲基-1-(4-二甲基氨基-苯乙烯基)环己烷(DCDDC).它们可作为有机发光显示器件的发光材料.比较了PBE0、M06、BMK、M062X和CAM-B3LYP五种泛函,其中BMK方法很好地再现了各个分子在丙酮溶剂中的吸收和发射光谱.同时计算了分子的电子亲和能和电离势并用于评价分子的电荷注入性质.研究表明,当使用双π桥和双受体时,分子的发射光谱会红移到理想的发光区域.据此设计了两个新的分子DCDCC2和DCDDC2,它们分别是DCDCC和DCDDC的双支对应分子.计算结果表明这两个分子也具有作为荧光发射体的良好性质.

TDDFT Investigation and Design for Fluorescent Molecules with Push-Pull Structures

The electronic and geometrical structures of the ground and excited states of six fluorescent emitters,namely 3-(dicyanomethylene)-5,5-dimethyl-1-(3-9-(2-ethyl-hexyl)-carbazol]-vinyl) cyclohexene(DCDHCC),DCDHCC2,3-(dicyanomethylene)-5,5-dimethyl-1(4-diphenylamino-styryl) cyclohexene(DCDPC),DCDPC2,3-(dicyanomethylene)-5,5-dimethyl-1-(4-9-carbazol]-styryl)cyclohexene(DCDCC),and 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styryl)cyclohexene(DCDDC) which were specifically designed for organic light-emitting diodes(OLEDs),were studied using density functional theory(DFT) and time-dependent DFT(TDDFT) in conjunction with polarizable continuum models(PCMs).Five hybrid functionals,PBE0,M06,BMK,M062X,and CAM-B3LYP,were used and compared.The experimental spectra of the molecules in acetone solvent were precisely reproduced with the BMK functional.The ionization potential and the electron affinity were calculated to access the properties of the molecules in charge injection.It was found that,when double π-bridges and acceptors were used,the emission of emitters red-shifted to the optimal emitting region.Two brand new molecules,DCDCC2 and DCDDC2,which are the double-branched counterparts of DCDCC and DCDDC,respectively,have been designed.The calculated properties of DCDCC2 and DCDDC2 in spectra and charge injection suggested that they would be as effective in their capacities as fluorescent emitters as the above six emitters.