Study on structure-property relationship of 1,5-naphthyridine-2,6-dione (NTD) derivatives for organic field-effect transistors

1;5-naphthyridine-2;6-dione;Small molecule;D-A structure;StructureProperty Relationship;Organic Field-Effect Transistor;620.1

Meilin Liu공과대학 재료공학부 ;

University:서울대학교 대학원

关键词: 1;    5-naphthyridine-2;    6-dione;    Small molecule;    D-A structure;    StructureProperty Relationship;    Organic Field-Effect Transistor;    620.1;   

Others  :  http://s-space.snu.ac.kr/bitstream/10371/161044/1/000000157617.pdf

美国|英语

来源: Seoul National University Open Repository

【 摘 要 】

AbstractStudy on structure-property relationship of 1,5-naphthyridine-2,6-dione (NTD) derivatives for organic field-effect transistorsOrganic field-effect transistors (OFETs) have attracted great attention due to their advantages of flexibility and solution processability. Many researchers have made great efforts on development of high-performance organic semiconductor materials and exploring their structure-property relationships to optimize the device performances. Among many organic semiconductors, organic molecules containing bis-lactam functional groups have been drawing special attention for high-performance OFET materials because of their high electron affinity, tunable solubility, and strong π-π interaction. Recently, a novel bis-lactam-based small molecule, 1,5-dioctyl-3,7-di(thiophene-2-yl)-1,5-naphthyridine-2,6-dione (NTDT), was developed. In comparison with the well-known bis-lactam-based semiconducting material such as 2,5-dioctyl-3,6-di(thiophen-2-yl) pyrrolo[3,4-c]pyrrole-1,4-dione (DPPT), NTDT exhibited more favorable thin-film morphology and electronic coupling structures for charge transport due to two-dimensional (2D) C-H‧‧‧O=C intermolecular interaction, highly planar molecular structure, and strong intermolecular π–π stacking. Although NTDT showed promising hole mobility in the OFETdevices, there is still much room for further improvement. Therefore, studying structure-property relationships of NTDT derivatives is highly desired. This study aims to investigate the effect of molecular planarity and crystallinity on the performance of OFET devices using NTDT-based semiconductors. In this work, we designed and synthesized a series of NTDT derivatives bearing additional two hexyl side chains at three different positions (α, β, and γ) in the thiophene rings of NTDT. Their optoelectronic properties were thoroughly investigated by UV-vis absorption, photoluminescence, and cyclic voltammetry (CV) measurements as well as theoretical calculation using density functional theory (DFT) method. It was found that the substitution position of the hexyl chains influenced molecular planarity of the NTDT derivatives, which significantly altered their optoelectronic and thermal properties as well as crystallinity in the solid state. Interestingly, the photoluminescence quantum yields (ΦPL) of the NTDT series were unity in solution state regardless of the substitution of additional hexyl chains. In contrast, in films, the NTDT derivatives showed different ΦPL values depending on the substitution position of the hexyl chains.Finally, vapor-deposited and solution-processed OFET devices were fabricated using the NTDT derivatives. In the vapor deposited devices, Octyl-NTDT-αhexyl showed the best hole mobility (μh) up to 0.44 cm2 V-1 s-1 among the series, while Octyl-NTDT-βhexyl showed the best μh as high as 9.11×10-2 cm2 V−1 s−1 in the solution-processed devices. In contrast, the μh of Octyl-NTDT-γhexyl was significantly low in both devices due to the twisted molecular structure. Through X-ray diffraction (XRD) studies, it was revealed that there was a correlation between the substitution position, crystallinity, and device performance of the NTDT derivatives.Keywords:1,5-naphthyridine-2,6-dione, Small molecule, D-A structure, Structure-Property Relationship, Organic Field-Effect Transistor.