Molecular semiconductor materials exhibit remarkably long room-temperature spin lifetimes, holding great promise for achieving efficient room-temperature spin transport and control. Investigating the structure-function relationship between the chemical structure of molecular semiconductor materials and their spin transport properties is crucial for developing efficient spin transport molecular semiconductor materials and constructing high-performance spin devices. Electron spin resonance (ESR) technique provides an effective measurement tool for this research.
Recently, the research group led by Dr. Sun Xiangnan at the National Center for Nanoscience and Technology has made new progress in the study of the relationship between molecular conformation and material spin lifetime using electron spin resonance technique. The relevant findings have been published online in Advanced Materials.
Isomerism is a typical phenomenon of organic semiconductor materials. Since the elemental composition of isomers is identical, it is generally believed that there is little difference in spin lifetime and transport performance between isomers. In molecular electronics research, two small molecular semiconductor materials, ITIC and BDTIC, which are structural isomers, have definite chemical structures and high purity.
Based on the study of the spin transport properties of ITIC and BDTIC isomers, the research group has demonstrated for the first time that although the charge transport and molecular stacking properties of thin films of ITIC and its structural isomer BDTIC are similar, their spin transport properties are completely different. Through further electron spin resonance experiments and density functional theory calculations, it was found that the non-covalent conformational lock formed in BDTIC can enhance the spin-orbit coupling along the spin transport path, thereby reducing the spin lifetime.
"The study shows that the influence of structural isomerism must be considered in the development of efficient spin transport molecular semiconductor materials. This provides a theoretical basis for measuring the amount of conformational locking in thin films and will also find wide applications in the study of molecular phase transitions and aggregate state structures," said Dr. Sun Xiangnan, the corresponding author of the paper and a researcher at the National Center for Nanoscience and Technology.
Related Paper Information: https://doi.org/10.1002/adma.202402001
