Carbon, Nitrogen, and Chalcogen Substitution Effects on 2,1,3-Benzothiadiazole Derivative： Theoretical Investigations of Electronic, Optical, and Charge Transport Properties

A series of CH2, NH, O, and Se substituted 2,1,3-benzothiadiazote derivatives have been designed and investigated computationally to elucidate their potential as organic light-emitting materials for organic light-emitting diodes. Both ab initio Hartree-Foek and hybrid density functional methods are used. It is found that S by CH2, NH, O, and Se makes it possible transport properties of the pristine molecule adjusting the central aromatic ring by replacing to fine-tune the electronic, optical, and charge

Simple substituents make big differences in photophysical performances of 2,1,3-benzothiadizole-conjugated spiropyrans

Developing multifunctional spiropyran dyes is of particular importance in diverse applications.In the present study,we synthesized two 2,1,3-benzothiadiazole-conjugated spiropyrans(BT-SP-NO2and BTSP-NMe2)with distinct substituents.These donor-acceptor-structured spiropyrans exhibited typical twisted intramolecular charge transfer features and strong emissions in low-polarity solvents with fluorescence quantum yields(QYs)of up to 90.7%.Like traditional spiropyrans,the electron-acceptor-substituted BT-SP-NO2exhibited excellent photochromic behavior under multiple alternating UV—Vis irradiation,while the electron-donor-substituted BT-SP-NMe2was an acidochromic dye.In addition,the substituent groups distinctly affected the packing modes of these spiropyrans in the solid state.BTSP-NMe2showed a much stronger solid-state emission(QY of 59.0%)than BT-SP-NO2.Moreover,these two dyes were utilized as biocompatible probes for the specific light-up imaging of lipid droplets.

2,1,3-苯并噻二唑类溴化物的合成及其性质研究

2,1,3-苯并噻二唑(BT)由苯环和噻唑环构成,具有较强大的共面性、吸电子能力、较好的空气稳定性和高载流子迁移率,可作为受体材料。另外,噻吩基为含有S原子的五元环结构,也具有强的供电子能力,两者通常被作为受体单元广泛应用于有机合成中。本文以2,1,3-苯并噻二唑为基体,引入噻吩基团以及溴原子进行改性,合成了4,7-双(2-溴-5-噻吩基)-2,1,3-苯并噻二唑。通过IR、NMR、MS来表征其分子结构和UV-Vis、PL研究其光谱性质。通过实验数据,发现引入溴原子后,产物的UV-Vis光谱产生相应的红移,其薄膜的UV-Vis光谱覆盖至700nm,且其荧光发射发生猝灭,表明了产物具有优良的光吸收性能。

CH_2,NH,and O heteroatom substitution effects on the electronic,optical,and charge transport properties of a 2,1,3-benzothiadiazole-based derivative:Insights from theory

A set of CH2-,NH-,and O-substituted 2,1,3-benzothiadiazole(BTD)-based derivatives have been investigated theoretically in order to explore their electronic,optical,and charge transport properties.The calculation results show that the electronic and optical properties of the pristine molecule can be easily tuned through changing the S substituent in the central aromatic ring.Based on the calculated maximum emission wavelength,we predict that CH2-,NH-,and O-substituted BTD-based derivatives could be used as red,green,and orange light-emitting materials,respectively.After CH2-,NH-or O-substitution,the oscillator strengths of the emission spectra are enhanced with respect to that of the pristine molecule,implying that these compounds have larger fluorescence intensity.Finally,it can be deduced that CH2-,NH-,and O-substituted BTD-based derivatives may act as hole transport materials in organic light-emitting diodes.

Recent progress of electronic materials based on 2,1,3-benzothiadiazole and its derivatives:synthesis and their application in organic light-emitting diodes

2,1,3-Benzothiadiazole(BT)and its derivatives are very important acceptor units used in the development of photoluminescent compounds and are applicable for the molecular construction of organic light-emitting diodes,organic solar cells and organic field-effect transistors.Due to their strong electron-withdrawing ability,construction of molecules with the unit core of BT and its derivatives can usually improve the electronic properties of the resulting organic materials.In this contribution,we review the synthesis of various polymers,small molecules and metal complexes with BT and its derivatives and their applications in organic light-emitting diodes.Furthermore,the molecular design rules based on these cores are discussed.

Side chains and backbone structures influence on 4,7-dithien-2-yl-2,1,3-benzothiadiazole （DTBT）-based Iow-bandgap conjugated copolymers for organic photovoltaics

Five 4,7-dithien-2-yl-2,1,3-benzothiadiazole （DTBT）-based conjugated copolymers with controlled molecular weight were synthesized to explore their optical, energy level and photovoltaic properties. By tuning the positions of hexyl side chains on DTBT unit, the DTBT- fluorene copolymers exhibited very different aggregation properties, leading to 60 nm bathochromic shift in their absorptions and the corresponding power conversion efficiencies （PCEs） value of photovoltaic cells varied from 0.38%, 0.69% to 2.47%. Different copolymerization units, fluorene, earbazole and phenothiazine were also investigated. The polymer based on phenothiazine exhib- ited lower PCE value due to much lower molecular weight owing to its poor solubility, although phenothiazine units were expected to be a better electron donor. Compared with the fluorene-based polymer, the carbazole-DTBT copolymer showed higher short circuit current density （Jsc） and PCE value due to its better intermolecular stacking,

The effect of diphenylamine on the electronic,optical,and charge transport properties of BTD-based derivative:Insights from theory

Theoretical investigations have been performed to explore the variation in electronic,optical,and charge transport properties upon the change of the chemical composition along the backbone in 2,1,3-benzothiadiazole（BTD）-based derivative.Narrow difference between hole and electron transportations with the charge hopping model indicates studied BTD-based derivative can be used as good ambipolar transport material in organic light-emitting diodes.