Structure design and property study of II-VI, VI-VI and I-VII based inorganic-organic hybrid semiconductors.

摘要

We have developed and studied selected properties of three novel classes of inorganic organic hybrid semiconductors based on II-VI, VI-VI and I-VII binary phases in order to enhance the functionality over their parent structures.;As a continuing effort, we have synthesized, modified, and characterized a number of selected structures of II-VI inorganic organic hybrid materials with general formula ZnSe(L)0.5 (L = organic diamine). The thermal expansion coefficients along the layer stacking (L3) axis are between -1x10-6 and 4x10-6 K-1 in the temperature range between 5K and 300K for all structures, indicating a nearly-zero linear thermal expansion in the direction. A very small negative thermal expansion coefficient of -7.8x10-7 K-1 is achieved for ZnSe( ptda)0.5 along the L3 axis, which is among the smallest values reported to date.;Secondly, we have designed a new class of inorganic organic hybrid semiconductors under mild solvothermal conditions. By controlling the dimensionality and topology of the VI-VI inorganic component using organic spacers, hybrid semiconductors with tunable optical properties can be effectively designed. The new VI-VI hybrid structures display the low thermal conductivities and high dielectric constants caused by interface induced phonon scattering and space charge polarization respectively. A significant negative thermal expansion behavior was also observed in some of the new VI-VI hybrid structures.;To further explore the unique properties of inorganic organic hybrid semiconductors, we have developed a novel class of I-VII inorganic organic hybrid semiconductors. A number of new 1D-CuI(L) ( L = organic ligand) inorganic organic hyrbid materials were acquired using a solvent diffusion method. The 1D-CuI(L) hybrid structures display tunable optical absorption and emission behavior with some structures able to give close-to--white-light photoluminesence. By adjusting the functional group on the organic molecules, their LUMO energy levels and the band gap of hybrid structures can be systematically tuned. This discovery further leads us to design ligand substituted 1D-CuI(L) structures to attain white light emission. We have successfully syntheisized pyrimidine substituted CuI(pyridine) crystals which demonstrate pure and strong white light emission, with the CIE cordinates of (0.31,0.33) under the UV excitation.