压力对有机半导体均苯四甲酸晶体结构转变和电子性质的影响

研究高压条件下均苯四甲酸(C₁₀H₆O₈)材料的结构和性质对探索有机半导体材料的应用有积极意义.基于密度泛函理论的第一性原理赝势平面波方法，开展了0-300 GPa压强下C₁₀H₆O₈晶体的结构、电子和光学性质的研究.晶格常数在压强20 GPa和150 GPa下出现了明显跳变，且原子之间随着压强变化反复地出现成键/断键现象，表明压强可诱导晶体结构变化.电子结构的性质表明，0 GPa的C₁₀H₆O₈晶体是带隙为3.1 eV的直接带隙半导体，而压强增加到150 GPa时，带隙突变为0 eV,表明了晶体由半导体转变为导体.当压强为160 GPa时，晶体又变成了能隙约为1eV的间接带隙半导体，这可能是费米能级附近仅受O-2p轨道电子影响所导致.通过对C₁₀H₆O₈晶体介电函数的分析，再次验证了晶体在150 GPa时发生了结构相变.同时...

Effect of pressure on the structure transitions and electronic properties of the organic semiconducting Benzenetetracarboxylic acid crystal

The study of the structure and properties of Benzenetetracarboxylic acid (C10H6O8) under high pressures is of positive significance to explore the application of organic semiconductor materials. Based on the first principle pseudo-potential plane wave method of density functional theory, the structural, electronic and optical properties of C10H6O8 crystal at 0-300 GPa are calculated. The lattice constants show the obvious jumps at the pressures of 20 GPa and 150 GPa, and the bonds between the atoms are formed/broken repeatedly with pressure increases, indicating that the pressure can induce the change of the crystal structure. The properties of the electronic structure show that the C10H6O8 crystal is a direct bandgap semiconductor at 0 GPa, while the band gap decreases to 0 eV at 150 GPa, which indicate that the crystal transforms from the semiconductor state to the conductor state. When the pressure is 160 GPa, the crystal becomes an indirect band-gap semiconductor with an energy gap of about 1eV, which may be caused by the influence of the O-2p orbital electrons near the Fermi level. By analyzing the dielectric function of C10H6O8 crystal, it is again verified that the structural phase transition occurs at 150 GPa. At the same time, the characteristic that the crystal conductivity increases with the increase of pressure shows that the crystal volume is compressed as the pressure increases, resulting in an increase in the number of conductive particles per unit volume.