Design, characterization and properties of nitrogen-containing novel organic N-type materials

• Main Author: Wu, Yuechao.
• Other Authors: School of Materials Science & Engineering
• Format: Theses and Dissertations
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/51233
• Institution: Nanyang Technological University

In past decades,organic semiconductors have caused a lot of interests because of their potential applications in field-effect transistors(FET),organic-light-emitting devices(OLED)and photovoltaic cells.Among them,developing high-efficient n-type organic materials for organic field-effect transistors(OFETs)is very urgent.Currently, p-type organic semiconductors are well-developed and their mobility can go as high as4.8 cm2V-1S-1.Since p-type and n-type materials are equally important for the fabrication of p-n junctions and complementary logic circuits,the demand to find the promising n-type counterparts is necessary. Although a lot of n-type organic materials have been reported,this research will specially focus on N-substituted polycyclic aromatic hydrocarbons(PAHs)because Houk et al predicted that the azaacenes have high electron affinities and could be promising candidates for n-type semiconducting materials.In fact,some N-heteroacenes have already shown decent electron mobility.Moreover,N-heteroacenes are more stable(resistive to oxidation or dimerization).In addition,the physical properties of n-substituted heteroacenes strongly depend on the number,position and valence states of nitrogen atoms.These progresses strongly encourage me to prepare larger azaacenes In this thesis,I have designed,synthesized and characterized several new azaacenes,which are expected to exhibit good performance in electronic devices.I developed a simple and efficient method(one or two steps)to prepare targeted azaacenes through condensation reaction starting from commercially available materials.All as-prepared compounds are very stable and have lower bandgaps.Phototransistors based on 6,8,15,17-tetraaza-1.18,4.5,9.10,13.14- tetrabenzoheptacene(TTP)single crystals have been fabricated and this device exhibited excellent performance in amplifying and converting light signal under the photoconductive effect.In addition,9,11,13,22,24,26-hexaza-tetrabenzo[a,c,l,n]heptacene(HATBH)can act as an efficient anion sensor for naked-eye detection of F- and H2PO4- anions and 9,26-dihydro 9,11,13,22,24,26-hexaza-tetrapyrido[3,2-a: 2’,3’-c:3”,2”-l:2”’,3”’-n]heptacene(DHATPH)can selectively sense F- anion among TEN anions(F-,Cl-,Br -,I-,PF6-,HSO4-,NO3-,BF4-,AcO-,and H2PO4-). The synthetic strategy in this thesis might offer a promising way to challenge larger azaacenes with more N atoms.The OFET performances based on these materials are under investigation.