The Study Of Synthesis And Performance Of Electron Transport Materials And Host Materials With Tunable Carriers Mobility

As we all known, balanced carrier transport is an efficient way to improve the device efficiency and lifetime. However, the research progress of electron transport material are far behind the hole’s, the development of mobility adjustable and energy marched electron transport materials even host materials have attracted much attentions for scientific researchers. Here, we used pyridine or pyrimidine as electron-withdrawing moiety to modify different conjugated groups, such as changing the position of nitrogen(2rd,4th Charpters), regulation the number of pyridine(3rd,5th Charpters), adjustment the ratio of electron drawing groups(6th,7th Charpters),. Besides these mobility adjustable and energy marched electron transport materials and host materials were explored by regulating the ratio of electron-withdrawing group andElectron transport materials with different polarity were obtained by gradually changing the position of nitrogen as a sequence of2-TmMiPb<3-TmMiPb<2,4-TmMiPb. All of the compounds exhibited high thermal stabilities (Tg>105℃) and high current efficient of34.97cd/A (2-TmMiPb). It is improved that the polarity of compound increased as the nitrogen moving to the terminal, but the gradually decreased LUMO levels enlarge the inject energy barriers and influence the device efficiencies. Moreover, Space limited charge current (SCLC) was applied to analysis the mobility changes;By using pyridine to modify the2,6,9,10position of anthracene, different polarity materials were obtained as a sequence of AnPy<AnDPy<AnTPy<AnFPy. The relative mobility was obtained by time of flight method (TOF) as a sequence of AnPy<AnDPy<AnTPy<AnFPy. It was improved that the marched mobility and energy level exhibited the optimum efficiency of the device. The maximum efficiency is140%larger than Alq3as electron transport material.By using pyridine as electron-withdrawing moiety to modify the2,7position of 9,9-diphenylfluorene in different positions or linkages, The mobility was carried out by Space limited charge current (SCLC). Combing with the device efficiency, FpPy3Py exhibits the highest efficiency as a result of high mobility and proper energy level.By using pyridine as electron-withdrawing moiety to modify the C and N position of phenanthroimidazole in different linkages, different polarity materials were obtained as a sequence of NPI-m3Py<NPI-p3Py<CPI-m3Py<CPI-p3Py<CNPI-m3Py=CNPI-p3Py. The mobility was carried out by Space limited charge current (SCLC) Combing with the device efficiency, CNPI-p3Py exhibits the highest efficiency as a result of high mobility and proper energy level.By using benzimidazole to modify the2,7position of9-methyl or phenyl fluorene, a series of mobility adjustable host materials were obtained with high glass-transition temperature. The mobility was carried out by Space Charge Limited charge current (SCLC) as a sequence of DmBIFPh> DmBIFMe> mBIFPh. Combing with the device efficiency, DmBIFPh exhibits the highest efficiency as a result of high mobility and balanced carrier recombination in emitting layer.By using tetraphenylethylene as electron donor group and diphenylphosphine oxide as electron withdrawing group to synthesis star-like linkage host materials, the mobility was adjustable by gradually adjusting the proportion of tetraphenylethene and phosphine oxide. The electron mobility was measured as a sequence of TPEDPO> TPEPO> DTPEPO> TTPEPO and the hole mobility as a sequence of TPEDPO<TPEPO<TPEPO<TPEPO. Combing with the device efficiency, TPEPO exhibits the highest efficiency, which suggest the more balanced carrier recombination.