Benzotriazole Unit Research Articles

Benzotriazole-Containing Planar Conjugated Polymers with Noncovalent Conformational Locks for Thermally Stable and Efficient Polymer Field-Effect Transistors

We report a series of benzotriazole-based semicrystalline π-conjugated polymers with noncovalent conformational locks for applications in polymer field-effect transistors. The benzotriazole moiety is a versatile electron-deficient building block that offers two chemically functionalizable sites, 2(N) and 5, 6(C) positions, allowing easy modulation of the solution processability and electronic structures of the resulting polymers. Fluorine or alkoxy substituents were introduced to the benzotriazole unit to enhance the molecular ordering through intra- and intermolecular F···S, F···H–C, C–F···πF, or S···O attractive interactions. The fluorinated polymer (PTBTz-F) showed remarkably enhanced hole mobility (μh = 1.9 cm2/(V·s), on/off ratio = 8 × 107) upon thermal annealing at 305 °C, compared to the unsubstituted one (PTBTz) (μh = 7.0 × 10–3 cm2/(V·s), on/off ratio = 3 × 106). Alkoxy unit substitution (PTBTz-OR) also improved the carrier mobility up to 0.019 cm2/(V·s) with an on/off ratio of 4 × 105. Fluorine ...

Electron deficient conjugated polymers based on benzotriazole

A series of solution processable conjugated polymers containing the benzotriazole unit have been synthesized and studied. The benzotriazole unit can be considered a moderately electron deficient building block that can readily incorporate a convenient alkyl substituent for solution processability. By varying the electron accepting strength of co-monomer partners, a series of polymers with different photophysical properties were obtained. Some polymers exhibit relatively high fluorescence quantum yields while others were able to quench the fluorescence of electron donor polymers in blends consistent with their ability to act as electron acceptors. The performance of these polymers as the active material in organic light emitting diode (OLED) and organic photovoltaic (OPV) devices is reported.

Rigid triarylamine-based D–A–π–A structural organic sensitizers for solar cells: the significant enhancement of open-circuit photovoltage with a long alkyl group

Five new organic D–A–π–A sensitizers DIA6–DIA10 containing benzothiadiazole (BTD) or benzotriazole (BTZ) as auxiliary electron withdrawing units have been synthesized. Their photophysical, electrochemical and photovoltaic properties have been studied. Consequently, although all of these dyes have long alkyl chains grafted on a π-bridge, DSSCs with dyes containing a BTZ unit displayed higher open circuit voltages (757–829 mV) than those containing a BTD unit (682–712 mV). This may be because the nitrogen-based heterocyclic group of BTZ can lift the conduction band edge and reduce the charge recombination that arises from the absence of the sulfur atom. Benefiting from this and the introduction of alkyl chains on the nitrogen atom, DSSCs with one dye containing BTZ and thieno[3,2-b]thiophene (TT) as the π-spacer (DIA7) showed the highest open circuit voltage (Voc = 829 mV). The addition of one more thiophene unit to DIA6 broadens the absorption spectra, leading the DIA8 device to produce the largest photocurrent. Among these sensitizers, the best photovoltaic performance was obtained by the DIA8 device, with a short circuit photocurrent density (Jsc) of 13.45 mA cm−2, an open-circuit photovoltage (Voc) of 757 mV, and a fill factor (FF) of 70%, corresponding to an overall conversion efficiency (η) of 7.15% which reached 93% of the reference dye N719-based cell under standard global AM 1.5 solar light conditions.

Synthesis and Optical and Electrochemical Studies on Dicationic Fluorenophanes

The synthesis of 2,7-bridged dicationic fluorenophanes consisting of benzimidazole, imidazole, and benzotriazole units and their absorption, photoluminescence, and electrochemical behavior are described.

Photovoltaic properties of benzotriazole containing alternating donor–acceptor copolymers: Effect of alkyl chain length

A series of variable alkyl chain length substituted donor–acceptor (D–A) conjugated polymers with thiophene ring as the donor and benzotriazole moiety as the acceptor has been investigated in bulk heterojunction solar cells. The optical and electrochemical properties showed that the absorption onsets and the energy levels of the copolymers were not affected by alkyl substitution revealing 1.9eV of optical band gap. The morphologies of the blend film can be fine-tuned by increasing the chain length attached to the benzotriazole unit. Photovoltaic devices were fabricated using (6,6)-phenyl-C61-butyric acid methyl ester (PC60BM) and (6,6)-phenyl-C71-butyric acid methyl ester (PC70BM) as the acceptors. The maximum performance was achieved with a Voc of 0.75V, Jsc of 3.70mA/cm2, FF of 45% and a PCE of 1.23% for the PTBT-DA10:PC70BM device using 1:4 w/w ratio in chlorobenzene (CB).

Conjugated Side-Chain-Isolated D–A Copolymers Based on Benzo[1,2-b:4,5-b′]dithiophene-alt-dithienylbenzotriazole: Synthesis and Photovoltaic Properties

Conjugated side-chain-isolated D–A copolymers, based on the donor unit of benzodithiophene (BDT) with a thiophene-conjugated side chain, thiophene π bridge, and the acceptor unit of benzotriazole (BTA) with or without fluorine substitution (PBDT-FBTA and PBDT-HBTA), were designed and synthesized for elucidating their structure–property relationships. The copolymer films demonstrated well-defined absorption peaks with steep absorption edges, consistent with their rigid and ordered structures in the solid films. The substitution of a thiophene-conjugated side chain on the BDT unit in the copolymers aroused 15-nm red-shifted absorption in comparison with its polymer analogues with alkoxy side chains on the BDT unit. Compared to PBDT-HBTA, PBDT-FBTA with two-fluorine-atom substitution on the BTA unit demonstrated a lower highest occupied molecular orbital energy level, higher hole mobility, and significantly better photovoltaic performance. A polymer solar cell (PSC) based on PBDT-FBTA/PC70BM (1:2, w/w) with ...

Novel proton conductive hybrid membranes based on sulfonated polysulfone and benzotriazole

Abstract

(1H-1,2,3-Benzotriazol-1-yl)methyl 2,2-dimethyl-propano-ate.

In the title compound, C12H15N3O2, the dihedral angle between the mean planes of the benzene and triazole rings is 0.331 (53) °. The side chain of the pivalate unit forms a dihedral angle of 69.04 (12)° with the benzotriazole unit. The ester group and two methyl groups of the pivalate unit are disordered with an occupancy ratio of 0.731 (3):0.269 (3). In the crystal, weak π–π stacking inter­actions are observed between inversion-related benzene rings [centroid–centroid distance = 3.9040 (1) Å].

In Situ Spectroelectrochemical Study of Positively and Negatively Charged States in a Donor/Acceptor EDOT/Benzotriazole‐Based Polymer

AbstractPositively and negatively charged states in cPBEBT, which consists of EDOT/benzotriazole/EDOT as the building block, are studied using CV, in situ UV‐Vis, and FTIR‐ATR spectroscopy. The results show that cPBEBT is an ambipolar D‐A‐type polymer capable of conducting both holes and electrons. The injected positive and negative charges are distributed over the whole polymer backbone, which is proven by in situ FTIR‐ATR where spectral signatures associated with the benzotriazole unit are observed in both p‐ and n‐doped cPBEBT. HOMO and LUMO values obtained from CV and FTIR‐ATR experiments during oxidation and reduction are compared. cPBEBT is an example of the D‐A approach towards the improvement of the electronic properties of the resultant polymer.

Incorporating Benzotriazole Moiety to Construct D–A−π–A Organic Sensitizers for Solar Cells: Significant Enhancement of Open-Circuit Photovoltage with Long Alkyl Group

Two novel benzotriazole-containing organic dyes based on D–A−π–A configuration, WS-5 with octyl group and WS-8 with methyl group, have been designed and synthesized for use in dye-sensitized solar cells (DSSCs). Compared with the traditional D−π–A sensitizers, the benzotriazole unit as an additional acceptor has several merits: (i) essentially facilitating the electron transfer from the donor to the acceptor/anchor; (ii) conveniently tailoring the solar cell performance with a facile structural modification on 2-position in the benzotriazole unit; and (iii) the nitrogen-containing heterocyclic group of benzotriazole being expected to improve the open-circuit photovoltage. The analysis of controlled intensity modulated photovoltage spectroscopy reveals that the replacement of methyl with octyl group enhances electron lifetime by 4-fold and retards charge recombination rate constant by 4-fold. The two dye-loaded TiO2 films possess almost the same conduction band position under the same condition, as revealed by the charge densities at open-circuit against open-circuit photovoltage. Therefore, the significant enhancement of open-circuit photovoltage from methyl to octyl group is attributed to the suppressed charge recombination. Under simulated AM1.5G solar light (100 mW cm–2), the DSSC based on WS-5 produces a short-circuit photocurrent of 13.18 mA cm–2, an open-circuit photovoltage of 0.78 V, a fill factor of 0.78, corresponding to a power conversion efficiency of 8.02%.

Bulk-Heterojunction Solar Cells with Benzotriazole-Based Copolymers as Electron Donors: Largely Improved Photovoltaic Parameters by Using PFN/Al Bilayer Cathode

Three benzotriazole (BTA)-based conjugated polymers PF-DTBTA, PCz-DTBTA, and PPh-DTBTA, with electron-donating segments of fluorene, carbazole, and dialkoxybenzene, respectively, were successfully synthesized as new polymeric donors in bulk-heterojunction (BHJ) photovoltaic cells (PVCs). All the copolymers exhibited good solubility in common organic solvents and good thermal stability. The optical band gaps for PF-DTBTA, PCz-DTBTA, and PPh-DTBTA are 2.24, 2.18, and 1.87 eV, respectively. The HOMO levels for PF-DTBTA, PCz-DTBTA, and PPh-DTBTA are −5.67, −5.54, and −5.20 eV, respectively, which were determined by the electron-donating segments. The LUMO levels for PF-DTBTA, PCz-DTBTA, and PPh-DTBTA are −3.43, −3.36, and −3.33 eV, respectively, which were mainly dominated by the BTA unit. For a blend ratio of polymer:PCBM = 1:2, BHJ PVCs with Al cathode displayed power conversion efficiencies (PCE) of 0.9%, 1.51%, and 1.16% for PF-DTBTA, PCz-DTBTA, and PPh-DTBTA, respectively. Alcohol-soluble poly[(9,9-dioct...

ChemInform Abstract: The Synthesis and Characterization of UV-Absorbing Azo-Pigments and Their Polymerizable Acryloyloxy and Methacryloyloxy Derivatives.

Abstract Mono- and diazo compounds of 5-(2-nitrophenyl-azo-)2,2',4,4'-tetrahydroxy-benzophenone and 5,5'-di( 2-nitrophenyl-azo- )2,2',4,4'-tetrahydroxybenzo-phenone have been synthesized by the azo-coupling reaction of o-nitrobenzenediazonium chloride with 2,2',4,4'-tetrahydroxyhenzophenone. Esterification of the mono-azo compound with acryloyl and methacryloyl chloride gave the monomeric acryloyloxy and methacryloyloxy azo-pigments in 57 and 59% yield. Reductive cyclization of the mono-azo compound gave a yellow product containing two types of ultra-violet absorbers, i.e. benzophenone and benzotriazole units. All compounds were characterized by their IR, UV. and 1H NMR.

Copolymers from benzodithiophene and benzotriazole: synthesis and photovoltaic applications

Two new alternating low bandgap copolymers from benzodithiophene and benzotriazole units, namely poly{4,8-bis(2-ethylhexyloxy)benzo[1,2-b; 3,4-b]dithiophene-2,6-diyl-alt-2-octyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole-5′,5′′-diyl} (PBDTDTBTz) and poly{4,8-bis(2-ethylhexyloxy)benzo[1,2-b;3,4-b]dithiophene-2,6-diyl-alt-2-dodecylbenzotriazole-4,7-diyl} (PBDTBTz), were designed and synthesized by a typical Stille coupling polymerization method. The copolymers were characterized by thermogravimetric analysis, UV-vis absorption and cyclic voltammetry. PBDTDTBTz and PBDTBTz possess moderate molecular weights and excellent thermal properties with a 5% weight loss temperatures (Td) around 300 °C. They exhibited good optical absorption, with peaks at 527 nm and 562 nm in the film state, respectively. Photovoltaic properties of the copolymers blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as electron acceptors, were investigated. The photovoltaic device with the PBDTDTBTz/PC71BM shows a power conversion efficiency of 1.7% with a short circuit current density of 4.5 mA cm−2 and a good fill factor of 0.62, while PBDTBTz demonstrated a moderate power conversion efficiency of up to 1.4%, under the illumination of AM 1.5, 100 mW cm−2 with a device structure of ITO/PEDOT: PSS/polymer: PC71BM (1 : 4)/Ca/Al. All the above information highlighted that this kind of the copolymers is promising for the application of polymer solar cells.

N-(1H-1,2,3-Benzotriazol-1-ylmethyl)phthalimide

The title compound [systematic name: 2-(1H-1,2,3-benzotriazol-1-ylmeth­yl)isoindole-1,3-dione], C15H10N4O2, was prepared by the reaction of 1H-benzotriazole and 2-bromo­methyl­isoindole-1,3-dione. The benzotriazole and isoindole units are almost planar and make a dihedral angle of 70.2 (1)° (mean planes include C and N atoms). A weak C—H⋯O intra­molecular hydrogen bond involving a carbonyl O atom as acceptor stabilizes the observed mol­ecular conformation.

1-(Benzimidazol-2-ylmethyl)-1H-benzotriazole hemihydrate

In the title compound, C14H11N5·0.5H2O, a methyl­ene carbon joins the benzimidazole and benzotriazole units with a C—N bond that is longer than a typical C=N double bond but shorter than a C—N single bond, providing potential as a synthetic auxiliary transformation reagent. A water mol­ecule inter­acts with the organic mol­ecule via inter­molecular hydrogen bonds.

3-(Benzotriazol-1-yl)-1-m-tolylpropan-1-one

In the title compound, C16H15N3O, the whole skeleton of non-H atoms is approximately planar; the dihedral angle is 1.45 (2)° between the benzene and triazole rings in the benzotriazole unit and 6.46 (1)° between the other terminal benzene ring and the benzotriazole unit. The crystal structure is stabilized by C—H...π interactions.

3-(1H-Benzotriazol-1-yl)-1-(3-methoxyphenyl)propan-1-one

In the title compound, C16H15N3O2, the dihedral angle between the benzotriazole unit and the other benzene ring is 79.06 (1)°. The crystal structure is stabilized by C—H⋯π inter­actions and van der Waals forces.

New benzotriazole derivatives as multifunctional ligands

A series of new multifunctional ligands based on the benzotriazole unit has been synthesized by condensation of hydroximethylbenzotriazole with carboxylic acid derivatives of pyridine, triphenylphosphine, ferrocene and thiophene. The coordination properties of these ligands towards cobalt, rhodium and iridium have been studied.

The synthesis and characterization of UV-absorbing azo-pigments and their polymerizable acryloyloxy and methacryloyloxy derivatives

Mono- and diazo compounds of 5-(2-nitrophenyl-azo-)2,2',4,4'-tetrahydroxy-benzophenone and 5,5'-di( 2-nitrophenyl-azo- )2,2',4,4'-tetrahydroxybenzo-phenone have been synthesized by the azo-coupling reaction of o-nitrobenzenediazonium chloride with 2,2',4,4'-tetrahydroxyhenzophenone. Esterification of the mono-azo compound with acryloyl and methacryloyl chloride gave the monomeric acryloyloxy and methacryloyloxy azo-pigments in 57 and 59% yield. Reductive cyclization of the mono-azo compound gave a yellow product containing two types of ultra-violet absorbers, i.e. benzophenone and benzotriazole units. All compounds were characterized by their IR, UV. and 1H NMR.

Functional polymers. LIV. Photochemical behavior of 2(2-hydroxyphenyl)2H-benzotriazole derivatives

Introduction of a second benzotriazole unit into 2(2-hydroxyphenyl)2H-benzotriazole structures causes a significant hyperchromic effect on the absorption spectra, the addition of a second hydrogen bonding hydroxyl group causes a small bathochromic shift, but a significant effect on the fluorescence spectrum.