21510-43-0Relevant articles and documents
Synthesis, morphology, and properties of poly(3- hexylthiophene)-block- poly(vinylphenyl oxadiazole) donor-acceptor rod-coil block copolymers and their memory device applications
Fang, Yi-Kai,Liu, Cheng-Liang,Li, Chaoxu,Lin, Chih-Jung,Mezzenga, Raffaele,Chen, Wen-Chang
, p. 3012 - 3024 (2010)
Novel donor-acceptor rod-coil diblock copolymers of regioregular poly(3- hexylthiophene) (P3HT)-block-poly(2-phenyl-5-(4-vinylphenyl)-1,3,4-oxadiaz- ole) (POXD) are successfully synthesized by the combination of a modified Grignard metathesis reaction (GRIM) and atom transfer radical polymerization (ATRP). The effects of the block ratios of the P3HT donor and POXD pendant acceptor blocks on the morphology, field effect transistor mobility, and memory device characteristics are explored. The TEM, SAXS, WAXS, and AFM results suggest that the coil block fraction significantly affects the chain packing ofthe P3HT block and depresses its crystallinity. The optical absorption spectra indicate that the intramolecular charge transfer between the main chain P3HT donor and the side chain POXD acceptor is relatively weak and the level of order of P3HT chains is reduced by the incorporation of the POXD acceptor. The field effect transistor (FET) hole mobility of the system exhibits a similar trend on the optical properties, which are also decreased with the reduced ordered P3HT crystallinity. The low-lying highest occupied molecular orbital (HOMO) energy level (-6.08 eV) of POXD is employed as charge trap for the electrical switching memory devices. P3HT-b-POXD exhibits a nonvolatile bistable memory or insulator behavior depending on the P3HT/POXD block ratio and the resulting morphology. The ITO/P3HT44-b-POXD18/Al memory device shows a non-volatile switching characteristic with negative differential resistance (NDR) effect due to the charge trapped POXD block. These experimental results provide the new strategies for the design of donoracceptor rod-coil block copolymers for controlling morphology and physical properties as well as advanced memory device applications.
Improving the electroluminescence performance of donor-acceptor molecules by fine-tuning the torsion angle and distance between donor and acceptor moieties
Qiu, Xu,Xue, Shanfeng,Wu, Yongjin,Chen, Mingshuai,Sun, Qikun,Yang, Wenjun
, p. 5988 - 5995 (2016)
The torsion angle and distance between the donor (D) and the acceptor (A) are two important factors in determining the photoluminescence and electroluminescence properties of twisted D-A type organic molecules. Here, two new D-A compounds, 2-(10-butyl-10H-phenothiazin-3-yl)-5-phenyl-1,3,4-oxadiazole (PO) and 2-(4-(10-butyl-10H-phenothiazin-3-yl)phenyl)-5-phenyl-1,3,4-oxadiazole (PPO), were designed and synthesized to tune the torsion angle and distance between D and A moieties, and their photophysical and electroluminescence properties were investigated. The D-A type molecule PO has a planar conformation, whereas the D-π-A type molecule PPO has a twisted conformation because of the insertion of the phenyl bridge between the donor and the acceptor. Therefore, the charge transfer (CT) of PPO is much stronger than that of PO, and the singlet exciton yield of PPO may be higher than that of PO. On the other hand, the introduction of a phenyl unit can also improve the photoluminescence quantum efficiency (doped film ΦPL ≈ 70%). As a result, the PPO-doped device showed better device performance than PO. The device based on PPO as an emitter exhibited stable and high luminous efficiency (15.2 cd A-1, corresponding to an external quantum efficiency of 5.4%), which is increased by about 1.05 fold as compared to the device based on PO as an emitter (luminous efficiency 7.4 cd A-1 and external quantum efficiency 2.9%).
Spiroconjugated Tetraaminospirenes as Donors in Color-Tunable Charge-Transfer Emitters with Donor-Acceptor Structure
Adachi, Chihaya,Adler, Florin,Chan, Chin-Yiu,Esser, Birgit,Grenz, David C.,Hermann, Mathias,Rose, Daniel,W?ssner, Jan S.,Wilbuer, Jennifer
, (2021/12/22)
Charge-transfer emitters are attractive due to their color tunability and potentially high photoluminescence quantum yields (PLQYs). We herein present tetraaminospirenes as donor moieties, which, in combination with a variety of acceptors, furnished 12 charge-transfer emitters with a range of emission colors and PLQYs of up to 99 %. The spatial separation of their frontier molecular orbitals was obtained through careful structural design, and two DA structures were confirmed by X-ray crystallography. A range of photophysical measurements supported by DFT calculations shed light on the optoelectronic properties of this new family of spiro-NN-donor-acceptor dyes.
Oxadiazole- and indolocarbazole-based bipolar materials for green and yellow phosphorescent organic light emitting diodes
Wu, Qiong,Braveenth, Ramanaskanda,Bae, Il-Ji,Zhang, Heng-Qiang,Jung, Hasu,Kim, Miyoung,Chai, Kyu Yun
, (2019/12/11)
New bipolar materials, namely 2-phenyl-5-(4-(5-phenylindolo [3,2-a]carbazol-12(5H)-yl)phenyl)-1,3,4-oxadiazole (ICz-OXD) and 2,5-bis(4-(5-phenylindolo [3,2-a]carbazol-12(5H)-yl)phenyl)-1,3,4-oxadiazole (2ICz-OXD), were designed and synthesized. Tree different devices were fabricated using ICz-OXD and 2ICz-OXD as host and fluorescent materials: a green phosphorescent, yellow phosphorescent, and non-doped fluorescent OLED emitter. The yellow phosphorescent OLED device based on the 2ICz-OXD host presented good maximum current, power, and external quantum efficiencies, whose values were 47.55 cd/A, 49.80 lm/W, and 21.54%, respectively. Its efficiencies were better than those of the devices based on ICz-OXD and on the reference material 4,4′-Bis(N-carbazolyl)-1,1′-biphenyl (CBP). The green phosphorescent OLED device with ICz-OXD revealed higher efficiencies than the device based on 2ICz-OXD. The current, power, and external quantum efficiencies based on ICz-OXD were 49.79 cd/A, 52.14 lm/W, and 16.50%, respectively. The non-doped fluorescent devices that used our bipolar materials (ICz-OXD, 2ICz-OXD) exhibited blue emission at 435 and 442 nm.
Experimental and Theoretical Studies on the Mechanism of DDQ-Mediated Oxidative Cyclization of N-Aroylhydrazones
Baek, Jihye,Je, Eun-Kyung,Kim, Jina,Qi, Ai,Ahn, Kwang-Hyun,Kim, Yongho
, p. 9727 - 9736 (2020/10/02)
The controversial single-electron-transfer process, frequently proposed in many 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-mediated reactions, was investigated experimentally and theoretically using the oxidative cyclization of aroylhydrazone with DDQ. DDQ-mediated oxadiazole formation involves several processes, including cyclization to form an oxadiazole ring and N-H bond cleavage, either by proton, hydride, or hydrogen atom transfer. The detailed mechanistic study using the M06-2X density functional theory, and the 6-31+G(d,p) basis set, suggests that the pathways involving radical ion pair (RIP) intermediates, which resulted from single-electron transfer (SET), were found to be energetically nearly identical to the pathway without the SET. The substituent-dependent reactivity of oxadiazole formation was consistent with the free energy profiles of both pathways, with or without the SET. This result indicates that in addition to the electron-transfer pathway, the nucleophilic addition/elimination pathway for DDQ should be considered as a possible mechanism of the oxidative transformation reaction using DDQ.
