Two donor/acceptor (D/A)‐based benzo[1,2‐b:4,5‐b′]dithiophene‐alt‐2,3‐biphenyl quinoxaline copolymers of P 1 and P 2 were synthesized pending different functional groups (thiophene or triphenylamine) in the 4‐positions of phenyl rings. Their thermal, photophysical, electrochemical, and photovoltaic properties, as well as morphology of their blending films were investigated. The poly(4,8‐bis((2‐ethyl‐hexyl)oxy)benzo[1,2‐b:4,5‐b'] dithiophene)‐alt‐(2,3‐bis(4′‐bis(N,N‐bis(4‐(octyloxy) phenylamino)‐ 1,1′‐biphen‐4‐yl)quinoxaline) ( P 2) exhibited better photovoltaic performance than poly(4,8‐bis((2‐ethylhexyl)oxy)benzo[1,2‐b:4,5‐b'] dithiophene)‐alt‐(2,3‐bis(4‐(5‐octylthiophen‐2‐yl)phenyl)quinoxaline) ( P 1) in the bulk‐heterojunction polymer solar cells with a configuration of ITO/PEDOT:PSS/polymers: [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM)/LiF/Al. A power conversion efficiency of 3.43%, an open‐circuit voltage of 0.80 V, and a short‐circuit current of 9.20 mA cm?2 were achieved in the P 2‐based cell under the illumination of AM 1.5, 100 mW cm?2. Importantly, this power conversion efficiency level is 2.29 times higher than that in the P 1‐based cell. Our work indicated that incorporating triphenylamine pendant in the D/A‐based polymers can greatly improved the photovoltaic properties for its resulting polymers. 相似文献
Compared with benzo[1,2‐b:3,4‐b′:5,6‐d″]trithiophene (BTT), an extended π‐conjugation fused ring derivative, dithieno[2,3‐d:2′,3′‐d′]benzo[1,2‐b:3,4‐b′:5,6‐d″]trithiophene (DTBTT) has been designed and synthesized successfully. For investigating the effect of extending conjugation, two wide‐bandgap (WBG) benzo[1,2‐b:4,5‐b′]dithiophene (BDT)‐based conjugated polymers (CPs), PBDT‐DTBTT, and PBDT‐BTT, which were coupled between alkylthienyl‐substituted benzo[1,2‐b:4,5‐b′]dithiophene bistin (BDT‐TSn) and the weaker electron‐deficient dibromides DTBTTBr2 and BTTBr2 bearing alkylacyl group, were prepared. The comparison result revealed that the extending of conjugated length and enlarging of conjugated planarity in DTBTT unit endowed the polymer with a wider and stronger absorption, more ordered molecular structure, more planar and larger molecular configuration, and thus higher hole mobility in spite of raised highest occupied molecular orbital (HOMO) energy level. The best photovoltaic devices exhibited that PBDT‐DTBTT/PC71BM showed the power conversion efficiency (PCE) of 2.73% with an open‐circuit voltage (VOC) of 0.82 V, short‐circuit current density (JSC) of 6.29 mA cm?2, and fill factor (FF) of 52.45%, whereas control PBDT‐BTT/PC71BM exhibited a PCE of 1.98% under the same experimental conditions. The 38% enhanced PCE was mainly benefited from improved absorption, and enhanced hole mobility after the conjugated system was extended from BTT to DTBTT. Therefore, our results demonstrated that extending the π‐conjugated system of donor polymer backbone was an effective strategy of tuning optical electronic property and promoting the photovoltaic property in design of WBG donor materials. 相似文献
We have synthesized four types of cyclopentadithiophene (CDT)‐based low‐bandgap copolymers, poly[{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl}‐alt‐(2,2′‐bithiazole‐5,5′‐diyl)] ( PehCDT‐BT ), poly[(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐(2,2′‐bithiazole‐5,5′‐diyl)] ( PocCDT‐BT ), poly[{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl}‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo[5,4‐d]thiazole‐5,5′‐diyl}] ( PehCDT‐TZ ), and poly[(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo[5,4‐d]thiazole‐5,5′‐diyl}] ( PocCDT‐TZ ), for use in photovoltaic applications. The intramolecular charge‐transfer interaction between the electron‐sufficient CDT unit and electron‐deficient bithiazole (BT) or thiazolothiazole (TZ) units in the polymeric backbone induced a low bandgap and broad absorption that covered 300 nm to 700–800 nm. The optical bandgap was measured to be around 1.9 eV for PehCDT‐BT and PocCDT‐BT , and around 1.8 eV for PehCDT‐TZ and PocCDT‐TZ . Gel permeation chromatography showed that number‐average molecular weights ranged from 8000 to 14 000 g mol?1. Field‐effect mobility measurements showed hole mobility of 10?6–10?4 cm2 V?1 s?1 for the copolymers. The film morphology of the bulk heterojunction mixtures with [6,6]phenyl‐C61‐butyric acid methyl ester (PCBM) was also examined by atomic force microscopy before and after heat treatment. When the polymers were blended with PCBM, PehCDT‐TZ exhibited the best performance with an open circuit voltage of 0.69 V, short‐circuit current of 7.14 mA cm?2, and power conversion efficiency of 2.23 % under air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW cm?2). 相似文献
Seven SGT organics dyes, containing bis‐dimethylfluoreneyl amino groups with a dialkoxyphenyl unit as an electron donor and a cyanoacrylic acid group as an anchoring group, connected with oligothiophenes, fused thiophenes and benzothiadiazoles as π‐bridges, were designed and synthesised for applications in dye‐sensitised solar cells (DSSCs). The photovoltaic performance of DSSCs based on organic dyes with oligothiophenes depends on the molecular structure of the dyes, in terms of the length change of the π‐bridging units. The best performance was found with a π‐bridge length of about 6 Å. To further enhance the photovoltaic performance associated with this concept, cyclopenta[1,2‐b:5,4‐b′]dithiophene (CPDT) and benzothiadiazole were introduced into the π‐bridge unit. As a result, the DSSC based on the organic dye containing the CPDT moiety showed the best photovoltaic performance with a short‐circuit photocurrent density (Jsc) of 14.1 mA cm?2, an open‐circuit voltage (Voc) of 0.84 V and a fill factor (FF) of 0.72, corresponding to an overall conversion efficiency (η) of 8.61 % under standard AM 1.5 irradiation. 相似文献
Dibenz[b,f]azepine (DBA) is a privileged 6‐7‐6 tricyclic ring system of importance in both organic and medicinal chemistry. Benzo[b]pyrimido[5,4‐f]azepines (BPAs), which also contain a privileged 6‐7‐6 ring system, are less well investigated, probably because of a lack of straightforward and versatile methods for their synthesis. A simple and versatile synthetic approach to BPAs based on intramolecular Friedel–Crafts alkylation has been developed. A group of closely‐related benzo[b]pyrimido[5,4‐f]azepine derivatives, namely (6RS)‐4‐chloro‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, C14H14ClN3, (I), (6RS)‐4‐chloro‐8‐hydroxy‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, C14H14ClN3O, (II), (6RS)‐4‐<!?tlsb=‐0.14pt>chloro‐8‐methoxy‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, C15H16ClN3O, (III), and (6RS)‐4‐chloro‐8‐methoxy‐6,11‐dimethyl‐2‐phenyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, C21H20ClN3O, (IV), has been prepared and their structures compared with the recently published structure [Acosta‐Quintero et al. (2015). Eur. J. Org. Chem. pp. 5360–5369] of (6RS)‐4‐chloro‐2,6,8,11‐tetramethyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, (V). All five compounds crystallize as racemic mixtures and they have very similar molecular conformations, with the azepine ring adopting a boat‐type conformation in each case, although the orientation of the methoxy substituent in each of (III) and (IV) is different. The supramolecular assemblies in (II) and (IV) depend upon hydrogen bonds of the O—H...N and C—H...π(arene) types, respectively, those in (I) and (V) depend upon π–π stacking interactions involving pairs of pyrimidine rings, and that in (III) depends upon a π–π stacking interaction involving pairs of phenyl rings. Short C—Cl...π(pyrimidine) contacts are present in (I), (II) and (IV) but not in (III) or (V). 相似文献
Electron‐deficient heterocycle 1,3,4‐oxadiazole is first introduced to the 2‐position of thieno[3,4‐b]thiophene (TT) to construct a new building block 2‐(thieno[3,4‐b]thiophen‐2‐yl)‐5‐(alkylthio)‐1,3,4‐oxadiazole (TTSO) with alkylthio chain. The polymer PBDT–TTSO based on TTSO and benzodithiophene (BDT) exhibits a deep lying highest occupied molecular orbital (HOMO) energy level of −5.32 eV and low‐bandgap of 1.62 eV. The power conversion efficiency (PCE) of 5.86% is obtained with a relatively high VOC of 0.74 V, a JSC of 13.1 mA cm−2, and FF of 60.5%. Furthermore, as S atom in thioether can be oxidized easily, the optoelectronic properties of PBDT–TTSO treated with different oxidants are preliminary investigated. Interestingly, the oxidation products still maintain high PCE with reduction less than 30%. This work demonstrates a new method to regulate HOMO energy levels by introducing electron‐deficient aromatic heterocyclic moiety.
Herein, we present a new synthetic approach to achieve selective supramolecular transformations and construct different interlocked metallacycles featuring a π‐electron‐deficient thiazolo[5,4‐d]thiazole‐derived ligand. We demonstrate that the formation of mono‐rings, interlocked rings ([2]catenanes) and Borromean rings can be controlled by adjusting the length of the binuclear half‐sandwich RhIII and IrIII building blocks. Furthermore, a concentration effect or D‐A stacking interaction between the pyrene guest and the thiazolo[5,4‐d]thiazole‐based ligand promotes a unique and reversible conversion between catenane structures and metalla‐rectangles. The synthetic results are supported by single‐crystal X‐ray diffraction analysis. 相似文献
A new class of [1,2,4]oxadiazolo[4,5‐a]thiazolo[2,3‐b]pyrimidin‐9(10H)‐one was prepared in moderate yields by the reaction of nitrile oxide with 2‐arylmethylidene‐6,7‐dihydro‐5H‐thiazolo[3,2‐a]pyrimidin‐3‐one. The reaction site of dipolarphile is the C?N of thiazolo[3,2‐a]pyrimidin‐3‐one rather than the expected C?C of arylmethylidene. The structures of the products were characterized thoroughly by IR, elemental analysis, MS, and NMR analysis. 相似文献