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Phase-dependent photoluminescence of non-symmetric 2,1,3-benzothiadiazole liquid crystals
摘要： In order to understand the effect of disubstitution on calamitic liquid crystals, a series of non-symmetric 2,1,3-benzothiadiazole compounds were synthesized and characterized. These specific molecular architectures without the C2 axis were prepared to investigate their mesomorphism and physical properties and to compare them with symmetric molecules. Their liquid crystalline behavior was studied by differential scanning calorimetry, polarized optical microscopy and X-ray diffraction. The thermal properties evidenced the influence of non-symmetric design on the formation of liquid crystalline phases. Photophysical studies were performed in solution and with films, where these materials displayed intense photoluminescence between 500–650 nm, high quantum yields (ΦF = 0.62 – 0.96) and strong solvatochromism. Photoluminescence was measured as a function of temperature, displaying a strong dependence on the phase.
关键词： Heterocycles,Liquid crystals,Luminescence,2,1,3-Benzothiadiazole
更新于2025-09-23 15:23:52
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Modification of the electronic properties of the π-spacer of chromophores linked to calix[4]arene platform for DSSCs applications
摘要： We have developed two novel dyes based on p-tert-butyl-calix[4]arene in order to evaluate their behavior as sensitizer in photovoltaic devices. These dyes consist in a difunctionalized calix[4]arene with triphenylamine (TPA)-donor, a heteroaromatic π-conjugated spacer, thiophene and benzothiadiazole-phenyl ring, respectively and cyanoacetic acid as acceptor group. The effect of the p -spacer has been studied by UV-vis spectroscopy and Differential Pulse Voltammetry and the models compounds have been theoretically investigated. The dye bearing phenylbenzothiadiazole results in a bathochromic shifted absorption and an adequate efficiency to transfer charge from D to A. The considerable increase of the photocurrent density results in a better efficiency of the devices prepared with these novel dyes with respect to the p-tert-butyl-calix[4]arene derivatives bearing TPA dye. In particular, p-tert-butyl-calix[4]arene derivative based on phenylbenzothiadiazole has reached an efficiency value of 5.84 % which means an increase of 33 % of the efficiency over those calix[4]arene derivatives with TPA dye.
关键词： aggregation,calix[4]arene,multichromophore,benzothiadiazole,metal-free sensitizer
更新于2025-09-23 15:23:52
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Non-Fused Non-Fullerene Acceptors with an Aa??Da??A'a??Da??A Framework and a Benzothiadiazole Core for High-Performance Organic Solar Cells
摘要： Non-fullerene acceptors (NFAs) have contributed significantly to the progress of organic solar cells (OSCs). However, most NFAs featured a large fused-ring backbone, which usually require tedious multiple-step synthesis and are not applicable to commercial application. An alternative strategy is to develop non-fused NFAs, which possess synthetic simplicity and facile tunability in optoelectronic properties and solid-state microstructures. In this work, we report two non-fused NFAs, BTCIC and BTCIC-4Cl, based on an A?D?A'?D?A architecture, which possess the same electron-deficient benzothiadiazole central core but different electron-withdrawing terminal groups. The optical properties, energy levels, and molecular crystallinities were finely tuned by changing the terminal groups. Moreover, a decent power conversion efficiency of 9.3% and 10.5% has been achieved by BTCIC and BTCIC-4Cl, respectively, by blending them with an appropriate polymer donor. These results demonstrate the potential of A?D?A'?D?A type non-fused NFAs for high-performance OSCs. Further development of non-fused NFAs will be very fruitful by employing appropriate building blocks and via side chain optimizations.
关键词： A?D?A'?D?A framework,benzothiadiazole,organic solar cells,non-fused acceptors,non-fullerene acceptors
更新于2025-09-23 15:19:57
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Bis(thiena??2a??yl)a??2,1, <scp>3a??benzothiadiazolea??diketopyrrolopyrrole</scp> a??based <scp>acceptora??acceptor</scp> conjugated polymers: Design, synthesis, and the synergistic effect of the substituent on their solar cell properties
摘要： Three acceptor–acceptor conjugated copolymers (TBT-DPP, FTBT-DPP, and HFTBT-DPP) with different substituent groups have been synthesized with palladium-catalyzed Stille coupling condensation polymerization assisted with microwave. Polymer solar cells (PSCs) based on these copolymers as the electron donors and PC71BM as the acceptor have been fabricated. The synergistic effect of the substituent between two fluorine atoms and hexyl alkyl chains in bis(thien-2-yl)-2,1,3-benzothiadiazole fragment on their solar cell properties has been investigated. Both the fluorine atoms and the synergistic effect can improve the solubility of the polymers effectively while the excellent thermal stability properties are still retained. Two fluorine atoms (polymer FTBT-DPP) increased the power conversion efficiency of the PSCs twice compared with TBT-DPP (without substituent). The synergistic effect (polymer HFTBT-DPP) decreased that seriously to zero. Density function theory calculations showed that the conjugation level of the polymer backbone is one of key factors. It demonstrates that the synergistic effect of fluorine atoms and alkyl chains in the same fragment does not always work well in improving the PSCs performance.
关键词： polymer solar cells,diketopyrrolopyrrole polymers,acceptor–acceptor conjugated,bis(thien-2-yl)-2,1,3-benzothiadiazole,synergistic effect
更新于2025-09-23 15:19:57
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Effect of fluorine substituents on benzothiadiazole-based Da????a??Aa?2a????a??A photosensitizers for dye-sensitized solar cells
摘要： Two D–π–A0–π–A organic dyes with triazatruxene (TAT) as the electron donor, thiophene as the π-spacer, benzoic acid as the anchor group, and benzothiadiazole (BT) or difluorobenzo[c][1,2,5]thiadiazole (DFBT) as the additional acceptor, namely LS101 and LS102, respectively, were applied to dye-sensitized solar cells (DSSCs). As fluorine substituents are usually strong electron-withdrawing groups, introducing two fluorine atoms into BT was expected to strengthen the electron-withdrawing ability of the auxiliary acceptor, resulting in DSSCs with a broader light capture region and further improved power conversion efficiency (PCE). Fluorine is the smallest electron-withdrawing group with an induction effect, but can also act as an electron-donating group owing to its conjugation effect. When the conjugation effect is dominant, the electron-withdrawing ability of additional acceptor DFBT decreases instead. Accordingly, the band gap of LS102 was broadened and the UV-vis absorption spectrum was blue-shifted. In the end, DSSCs based on LS101 achieved a champion PCE of 10.2% (Jsc = 15.1 mA cm?2, Voc = 966 mV, FF = 70.1%) while that based on LS102 gave a PCE of only 8.6% (Jsc = 13.4 mA cm?2, Voc = 934 mV, FF = 69.1%) under standard AM 1.5G solar irradiation (100 mW cm?2) with Co2+/Co3+ as the electrolyte.
关键词： Power conversion efficiency,Fluorine substituents,Organic photosensitizers,Benzothiadiazole,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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Small molecule donor based on alkoxylated benzothiadiazole unit: Synthesis and photovoltaics properties
摘要： Two small molecule donors (namely BTRO and BTCN) based on the benzothiadiazole unit were synthesized in this study. In comparison to BTRO, BTCN has a narrower absorption spectrum, however, BTCN has better crystallinity, higher carrier mobility, and better light absorption that is complementary to IDIC-4F. Non-fullerene all small molecule organic solar cells (SM-OSCs) based on BTCN: IDIC-4F exhibited a power conversion efficiency (PCE) of 4.62% with short circuit current density (Jsc) of 11.46 mA/cm2, open-circuit voltage (Voc) of 0.89 V, and fill factor (FF) of 0.45. In contrast, non-fullerene SM-OSCs based on BTRO: IDIC-4F showed PCE, Jsc, Voc, and FF values of 4.08%, 11.04 mA/cm2, 0.91 V, and 0.41, respectively. Our results show that benzothiadiazole is a very good acceptor unit for regulating the absorption and energy levels of non-fullerene SM-OSCs.
关键词： benzothiadiazole,all small molecule organic solar cells,non-fullerene,small molecule donor
更新于2025-09-19 17:13:59
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What can we learn from model systems: Impact of polymer backbone structure on performance and stability of organic photovoltaics
摘要： We report the synthesis and extensive investigation of a broad family of novel (X-DADAD)n conjugated polymers with different X building blocks. It was shown that variation of X block in polymer backbone represents an efficient approach for tuning the polymer optical properties, frontier energy levels, charge transport characteristics as well as thin-film morphology and photovoltaic characteristics. Decent power conversion efficiencies (5.1–5.7%) were achieved for solar cells based on the polymers comprised of dibenzosilole (P2) and carbazole (P3) units. Polymers P2 and P3 showed impressive indoor and outdoor stability in solar cells while clearly outperforming common benchmark materials. In the view of the obtained results, the designed (X-DADAD)n polymers can be considered as promising semiconductor materials for stable organic photovoltaics.
关键词： Operational stability,Organic solar cells,Thiophene,Conjugated polymers,Benzothiadiazole
更新于2025-09-19 17:13:59
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Investigation of newly designed asymmetric chromophore in view of power conversion efficiency improvements for organic solar cells
摘要： The organic chromophore of (D1-π-A-D2) type, (E)-4-(3,5-dimethoxystyryl)-7-(5'-hexyl-[2,2'-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole, OMe-BBTz, was synthesized using 2,1,3-benzothiadiazole as an acceptor with dimethoxyphenyl and hexyl bithiophene as donor units for the fabrication of bulk-heterojunction organic solar cells (BHJ-OSCs). The synthesized OMe-BBTz chromophore was comprehensively analyzed through structural, thermal, electrochemical, and photovoltaic characterizations. Reasonable HOMO (-5.39 eV) and LUMO (-3.41 eV) energy levels along with the optical band gap of ~1.98 eV were observed. The power conversion efficiency (PCE) of ~3.53 % with the short circuit current density (JSC) of ~8.71 mA/cm2 and the open-circuit voltage (VOC) of ~0.698 V were achieved by BHJ-OSCs with OMe-BBTz:PC61BM (1:3, w/w) active layer.
关键词： Organic solar cells,π-spacer,Benzothiadiazole,Structural,Thin film
更新于2025-09-19 17:13:59
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Theoretical Study on Structural Properties of Silicon-doped Benzothiazole/SnO2 (100): A Novel Molecular Design for Solar Cells
摘要： Conjugated polymers have recently drawn interest owing to their high-power conversion efficiency in bulk heterojunction solar cells. Based on 4-(5-bromothiophen-2-yl)-7-(5-((4-nonyl-5-ethynylthiophen-2-yl) ethynyl)-thiophen-2-yl) benzothiadiazole (A4B7BT), organic polymer monomers for solar cells are designed, aided by silicon-doping, using density functional theory (DFT) at the GGA/PW91/DNP level. Comparison and screening of stable configuration, stable energy, and frontier orbital energy gap indicate that, A4B7BT-3Si is the best configuration when the positions of 1, 3, and 5 carbon atoms on the BT unit of A4B7BT are replaced by 3 Si atoms simultaneously. To further explore the photovoltaic (PV) properties of silicon-doped A4B7BT, DFT and the periodic plane slab model are combined to investigate A4B7BT-xSi (x=1–6) adsorbed on the SnO2 (100) surface. The stable structures, Mulliken charges, frontier orbitals, energy band structures, and density of states are discussed in detail. The results reveal that the energy gap (1.17 eV) in SnO2 (100)-A4B7BT-3Si is close to that of single-crystal Si. This study potentially guides the strategic development of future PV materials.
关键词： density functional theory,silicon-doped,4-(5-bromothiophen-2-yl)-7-(5-((4-nonyl-5-ethynylthiophen-2-yl)ethynyl)thiophen-2-yl)benzothiadiazole,SnO2 (100) surface
更新于2025-09-16 10:30:52
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New organic materiel based on benzothiadiazole for Photovoltaic application Solar Cells
摘要： In this work, we have studied conjugated polymers based on benzothiadiazole. the quantum chemical calculations on the structure and electronic and optics properties using the density functional theory (DFT), for the ground- and excited-state properties, respectively, using CAM-B3LYP and the 6-31G(d, p) basis set. These results will be devoted to the influence of the substitution benzothiadiazole on the electronic and optoelectronic properties of the polymer. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of these compounds were calculated and compared to LUMO of fullerenes,C60 [6,6]-phenyl- C61-butyric-acid methyl ester to estimate the effectiveness of these molecules as electron donors in bulk heterojunction (BHJ) small molecules-fullerene solar cells. The absorption energies have been obtained from TD-DFT calculations performed on the excited-state optimized S geometries. Finally, the theoretical results suggest that both the introduction of benzothiadiazole groups contribute significantly to the electronic and optoelectronic properties of the alternating donor–acceptor–donor conjugated systems studied.
关键词： Benzothiadiazole,BHJ,DFT,Optoelectronic properties,Photovoltaic cells
更新于2025-09-12 10:27:22