| Molecular design plays an important role in improving the efficiency and performance of OFET devices,and designing materials with high mobility is one of the keys to building high-performance OFET devices.In order to explore the strategy of designing high-mobility organic semiconductor material molecules,starting from the two directions of molecular planarity and reorganization energy,according to the gridization strategy of organic semiconductors,BDT is selected as the monomer to construct rigid bulky structures with extended conjugation.Different from the previous ladder-type nanogridarenes,the previous nanogridarenes are hindered by the steric hindrance effect brought by the lattice of fluorenyl groups,which reduces the degree of electronic coupling,thus limiting the improvement of charge mobility.BDT is a symmetric planar conjugated π-π bridge that is prone toπ-π stacking and can facilitate intermolecular interactions.In order to verify the influence of gridization effect on molecular reorganization energy,and to explore the influence of planarization strategy on molecular,reorganization energy,ring strian energy,intramolecular non-covalent interaction,electrostatic potential,charge transfer,internal reorganization energy,normal mode analysis,absorption spectrum,emission spectrum and other propertiesthe of ground state molecular structures of several types of ladder lattice arenes based on BDT units were calculated using hybrid density functional theory.The specific results are as follows:(i)The BT-base and BDT-base fac-on grid have the following gridization effects: After gridization,the HOMO-LUMO energy gap of the molecule decreased by about 1.73 e V and1.26 e V,and the hole recombination energy decreased by about 0.079 e V and 0.042 e V,respectively.The planarization strategy of increasing the benzene ring in the molecule improves the planarity of the molecule,the hole reorganization energy decreases by about0.02 e V and 0.007 e V,the adiabatic ionization potential decreases by about 0.1 and 0.03 e V,and the adiabatic electron affinity increases sequentially larger by about 0.04 and 0.05 e V;(ii)When the “conformational lock” and group replacement strategy are introduced into the nanogridarenes,the “conformation lock” of the sulfur atom and the methoxy group,the benzene ring connected to the 5-position of the BDT unit are replaced by thiophene,the benzene ring connected to the 2-position of the BDT unit are replaced by thiophene and the four benzene rings in nanogridarenes are all replaced by thiophene have limited effect on the improvement of molecular planarity and the reduction of reorganization energy.However,after using 2-fluorothiophene to replace the benzene ring in the molecule,and at the same time the S···F interaction in the two 2-fluorothiophenes acts to form a “conformational lock”,the planarity of the molecule is improved,and the hole reorganization energy and electron reorganization can be reduced,especially the electron recombination energy,the molecule may be a potential bipolar transport material;(iii)By connecting another or two identical face-on grid on the basis of one face-on grid,the following “parallel-three” nanogridarenes growth effects were found.The molecular structures of “parallel” and “triple” continue the characteristics of “single”,with bridged HOMO/LUMO orbitals between π planes.The growth effect can effectively reduce the hole reorganization energy,electron reorganization energy and adiabatic ionization potential,and increase the adiabatic electron affinity.These results show that the ladder-type lattice arenes have high planarity and low recombination energy through organic semiconductor lattice and planarization strategies,which provide theoretical guidance for the experimental design and synthesis of organic semiconductor materials with high mobility. |
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