333432-27-2Relevant articles and documents
Screening metal-free photocatalysts from isomorphic covalent organic frameworks for the C-3 functionalization of indoles
Chen, Xiong,Feng, Xiao,Han, Songjie,Li, Chunzhi,Li, He,Li, Ziping,Liu, Xiaoming,Shao, Pengpeng,Xia, Hong
supporting information, p. 8706 - 8715 (2020/05/16)
The visible-light-driven organic transformation using two-dimensional covalent organic frameworks (2D-COFs) as metal-free heterogeneous photocatalysts is a green and sustainable approach, and it has gained a surge of interest by virtue of the photosensitizer's high crystallinity, abundant porosity, outstanding stability, excellent light-harvesting ability and tunable structure. However, the guiding principle for designing, constructing and selecting COF-based photocatalysts has not been put forward so far. Herein, we contribute a fascinating strategy to guide the acquisition of excellent framework photocatalysts, which is to screen them from a series of isomorphic COFs. As a proof of concept, three new isomorphic pyrene-based 2D-COFs (COF-JLU23, COF-JLU24 and COF-JLU25) with variable linkers were successfully synthesized. In addition to having similar crystallinity and porosity with the same pore size and shape, their absorption, emission, bandgap, energy level, transient photocurrent response and photocatalytic activity could be easily adjustedviaconfiguring different linkers in frameworks. Indeed, COF-JLU24 with electron donor-acceptor characteristics exhibited the best photocatalytic activity among the three isomorphic COFs for C-3 functionalization reactions of indoles, even better than that of the metal-free photocatalyst g-C3N4. More importantly, the screened COF-JLU24 as a metal-free photocatalyst still displayed extensive substrate adaptability and excellent recyclability. We anticipate that this strategy will become a robust rule of thumb for fast access to COF-based photocatalysts. In addition, we still highlight that the present study broadens the applied frontier of COF-based photocatalysts.
Influence of the auxiliary acceptor on the absorption response and photovoltaic performance of dye-sensitized solar cells
Wu, Zhifang,Li, Xin,Li, Jing,Hua, Jianli,Agren, Hans,Tian, He
, p. 3549 - 3557 (2015/02/19)
Three new dyes with a 2- (1,1-dicyanomethylene)rhodanine (IDR-I, -II, -III) electron acceptor as anchor were synthesized and applied to dye-sensitized solar cells. We varied the bridging molecule to fine tune the electronic and optical properties of the dyes. It was demonstrated that incorporation of auxiliary acceptors effectively increased the molar extinction coefficient and extended the absorption spectra to the near-infrared (NIR) region. Introduction of 2,1,3-benzothiadiazole (BTD) improved the performance by nearly 50%. The best performance of the dye-sensitized solar cells (DSSCs) based on IDR-II reached 8.53% (short-circuit current density (Jsc)=16.73 mAcm-2, open-circuit voltage (Voc)=0.71 V, fill factor (FF)= 71.26%) at AM 1.5 simulated sunlight. However, substitution of BTD with a group that featured the more strongly electron-withdrawing thiadiazolo [3,4- c]pyridine (PT) had a negative effect on the photovoltaic performance, in which IDR-III-based DSSCs showed the lowest efficiency of 4.02%. We speculate that the stronger auxiliary acceptor acts as an electron trap, which might result in fast combination or hamper the electron transfer from donor to acceptor. This inference was confirmed by electrical impedance analysis and theoretical computations. Theoretical analysis indicates that the LUMO of IDR-III is mainly localized at the central acceptor group owing to its strong electron-withdrawing character, which might in turn trap the electron or hamper the electron transfer from donor to acceptor, thereby finally decreasing the efficiency of electron injection into a TiO2 semiconductor. This result inspired us to select moderated auxiliary acceptors to improve the performance in our further study.
Two novel ambipolar donor-acceptor type electrochromic polymers with the realization of RGB (red-green-blue) display in one polymer
Zhao, Hui,Tang, Daidi,Zhao, Jinsheng,Wang, Min,Dou, Jianmin
, p. 61537 - 61547 (2015/02/19)
Two novel electrochromic monomers, 4,7-bis(4-methoxythiophen-2-yl)-[1,2,5]thiadiazolo[3,4-c]pyridine (MOTTP) and 4,7-bis(4-butoxythiophen-2-yl)-[1,2,5]thiadiazolo[3,4-c]pyridine (BOTTP), were synthesized and electropolymerized to give the corresponding polymers PMOTTP and PBOTTP, respectively. For the investigation of their electrochemical and electrochromic properties, the polymers were characterized using cyclic voltammetry (CV), UV-vis spectroscopy, step profiling, and scanning electron microscopy (SEM). The band gaps of the polymers were calculated based on spectroelectrochemical analysis, and were found to be 0.950 eV and 1.088 eV for PMOTTP and PBOTTP, respectively. Electrochromic investigations showed that PMOTTP and PBOTTP showed similar multichromic behaviors: saturated green color in the neutral state, highly transmissive blue in the oxidized state, and saturated red in the reduced state (red-green-blue, RGB). In addition, both polymers have excellent switching properties with more than 60% optical contrast in the NIR region and about a 0.5 s response time from neutral to oxide. Moreover, via electrochemical and spectral analyses both polymers were proven to be n-type dopable polymers. Hence, both polymers are promising materials to complete RGB electrochromic polymers for commercial applications.
High-mobility low-bandgap conjugated copolymers based on indacenodithiophene and thiadiazolo[3,4-c]pyridine units for thin film transistor and photovoltaic applications
Sun, Ying,Chien, Shang-Chieh,Yip, Hin-Lap,Zhang, Yong,Chen, Kung-Shih,Zeigler, David F.,Chen, Fang-Chung,Lin, Baoping,Jen, Alex K.-Y.
experimental part, p. 13247 - 13255 (2011/12/16)
Two new semiconducting polymers based on indacenodithiophene and thiadiazolo[3,4-c]pyridine units were synthesized via Stille coupling polymerization. The polymers, PIDTPyT and PIDTDTPyT, exhibited main absorption bands in the range of 550-800 nm while their absorption maxima were located at around 700 nm in films. With two additional thiophene spacers, PIDTDTPyT showed a broader absorption band but a 20 nm blue-shifted maximum peak compared to that of PIDTPyT. Both of the polymers possess low bandgaps (～1.6 eV) and deep energy levels for both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Organic field-effect transistors (OFETs) device measurements indicate that PIDTPyT and PIDTDTPyT have high hole carrier mobilities of 0.066 and 0.045 cm2 V-1 s -1, respectively, with the on/off ratio on the order of 10 6. Bulk heterojunction photovoltaic devices consisting of the copolymers and PC71BM gave power conversion efficiencies (PCE) as high as 3.91% with broadband photo-response in the range of 300-800 nm. The relationships between the photovoltaic performance and film morphology, energy levels, hole mobilities are discussed.
