El Theoretical Study Of The Organic Hole Transport Materials

Electron transfer is one of the most fundamental reactions, which is ubiquitous in chemistry, physics, biological and material science. The popularity of the electron transfer process determines the importance and urgency of electron transfer reaction. For the past decades, although the experiment researches related to electron transfer have made several breakthroughs in many other fields, especially recently, with the rapid development of the experimental techniques, the femtosecond technology is used to observe many long-distance electron transfer phenomenon, but the mechanism that controls the electron transfer is not clear enough yet, but how to explain these electron transfer theoretically, and ensure the electron transfer mechanism, research on the related dymanics issues, and provide theoretical accordance to the manual control of the electron transfer process, have a straight realistic significance.The research of the photoluminescence mechanism has a amazingly fast development in the past decade. In the long run, OLED has a fine develop foreground. At the moment, to design and compound new organic hole hopping transfer material is still an important issue.The OLED hole-hopping process can also be depicted as an electron-transfer reaction. The mobility of electron and hole are important in optiming the performance of OLED device, high mobility reduces the resistance of the device leading to high power efficiency. In addition, the relative mobility of electron and hole in the same material can also effect the power efficiency. In this work, we investigate the geometric and electric structures as well as the reorganization energy of TPD and PPD. Based on the Marcus theory, and recognition energyλchosen as the research parameter, the work recalculate a series of derivatives, and many innovative results can be listed as belows:(1)PPV is a typical, linear, conjugate macromolecule. With the enlargement of n(degree of polymerization), the geometry structure of molecule stays the same, yet the average degree of the molecule interval has increased. Generally, from the perspective of the molecule structure, the absolute value of dihedral angel is smaller than 0.1. The trunk atom of the whole system has a superior coplanarity, and this characteristic is beneficial to the electron delocalization. The increased number of the chain constitutional units does not effect the coplanarity trend of trunk 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 energy level of HOMO orbit, while decrease the ionization potential, at the same time, the recognition energyλincreases, which is not beneficial to the hole hopping transfer. While electrophilic substitute decreases the recognition energyλ, which is beneficial to the hole hopping transfer. This conclusion provides a theoretical accordance to choosing suitable electrophilic substitute and designing good hole hopping transfer material, which has a practical significance.( 2 ) It is also concluded that the chemical modifications (electrophilic substitute such as CF3 CN F, electron donating substitute, such as OH NH2 OCH3, etc.) on TPD's side phenyl could include the variety of the reorganization energy. And this is attributed to the interaction of inductive effect and conjugated effect. Electron withdrawing group, positive conjugated effect of substitute choice at the meta-position and negative conjugated effect of choice at the para-position will decrease the reorganization energy of TPD. It is also concluded that the chemical modification of the central biphenyl moiety of the TPD could induce the variety of the reorganization energy. And this is attributed to intersection of electronic effect and conjugated effect according to the different electronic effect of various substitutes, we can classify them into two kinds: one kind of substitutes is like F group, of which inductive and conjugated effect are not in consistent with each other. Electron donating group , positive conjugated effect of substitutes choice at the meta', mera-position and oO'position and negative conjugated effect of substitutes choice at the mM'position and oO'position will increase the reorganization energy of TPD. While electron withdrawing group, positive conjugated effect of substitutes choice at the mM'position and oO'position and negative conjugated effect of substitutes choice at the meta', mera-position and oO'-position will decrease the reorganization energy of TPD. The other kind of substitutes, it's inductive and conjugated effect are in consistent with each other. Electron donating group, positive conjugated effect of substitutes choice at the mM'position and oO'position and negative conjugated effect of substitutes choice at the meta', mera-position and oO'position will increase the reorganization energy of TPD. While electron withdrawing group, positive conjugated effect of substitutes choice at the meta', mera-position and oO'position and negative conjugated effect of substitutes choice at the mM'position and oO'position will decrease the reorganization energy of TPD.