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Synthesis and characterization of novel benzodithiophene-fused perylene diimide acceptors: Regulate photovoltaic performance via structural isomerism
摘要： Two isomeric benzodithiophene-fused perylene diimides, BPDI-1 and BPDI-2, are designed and synthesized via photo-induced ring-closure reaction between perylene diimide (PDI) acceptor and both isomeric benzodithiophene donor cores, including benzo[2,1-b:3,4-b']dithiophene (BDP) and benzo[1,2-b:4,3-b']dithiophene (BdT). The effect of structural isomerism on the molecular geometry, absorption, energy level, film morphology as well as photovoltaic performance is comparatively studied. It is found that the variation of the S atom substituted position in the donor cores results in distinct molecular geometries for the newly-developed BPDI-1 and BPDI-2 acceptors. Compared with BDP-containing BPDI-1, the incorporation of BdT core endows BPDI-2 with a remarkably enhanced backbone distortion. When blended with the commercially available polymer donor (PTB7-Th), such twisted structure feature for the BPDI-2 acceptor plays a key role in reducing molecule aggregation, which is helpful for the enhancements of short-circuit current density and photovoltaic efficiency effectively. As a result, non-fullerene solar cells fabricated from BPDI-2 acceptor achieve higher photovoltaic efficiency (4.44%) than that of BPDI-1 (2.98%), mainly benefited from superior short-circuit current density. This work provides us comparative understanding of isomeric geometry and device performance.
关键词： Benzodithiophene,Molecular geometry,Non-fullerene organic solar cells,Perylene diimide derivatives
更新于2025-11-19 16:56:42
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Synthesis and electrochromic properties of electrochromic polymers based on propylenedioxythiophene, diketopyrrolopyrrole and benzodithiophene units
摘要： Two novel soluble polymers, PD-1 and PD-2, were synthesized based on three kinds of monomers, including propylenedioxythiophene (ProDOT), diketopyrrolopyrrole (DPP) and benzodithiophene (BDT), via Stille coupling reaction with the feed ratios (ProDOT:BDT:DPP) of 3:4:1, and 1:2:1, respectively. Wherein, propylenedioxythiophene (ProDOT) and benzodithiophene (BDT) exist as the donor unit, and diketopyrrolopyrrole (DPP) as the acceptor units. Both of the two copolymers were characterized via 1H NMR, FT-IR spectra, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), spectroelectrochemistry, switching kinetics, colorimetry and thermogravimetric analysis. Electrochemical studies demonstrate that both copolymers have the ability of rapid doping and dedoping and excellent stability. PD-1 displays a brown color in the neutral state, and a light green color in the oxidized state, while PD-2 exhibits gray green color in the neutral state and a transparent light green color in the oxidized state. As the content of the DPP remains constant, the changes in the content of the ProDOT unit can effectively control the color changes of the copolymers without apparent changes in bandgap (Eg) values, and subsequently lead to the fine tune of the other properties of the copolymers, such as optical contrast, response time and coloring efficiency. The Eg values of PD-1 and PD-2 are 1.55 eV and 1.52 eV, respectively. The optical contrasts are 42.36% (1600 nm) for PD-1 and 67.74% (at 1620 nm) for PD-2, both are ideal candidate materials for the fabrication of near infrared devices. They also have moderate optical contrast in the visible region, with fast response time and high coloring efficiency.
关键词： Electrochromic property,Diketopyrrolopyrrole,Propylenedioxythiophene,Benzodithiophene,Soluble copolymer
更新于2025-09-23 15:21:01
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Developing Wide Bandgap Polymers with Single Benzodithiophene-Based Unit for Efficient Polymer Solar Cells
摘要： In this work, a series of solely benzodithiophene-based wide bandgap polymer donors, namely PBDTT, PBDTS, PBDTF and PBDTCl, were developed for efficient polymer solar cells (PSCs) by just varying the heteroatoms into the conjugated side chains. The effects of sulfuration, fluorination and chlorination were also investigated systematically on the overall properties of these BDT-based polymers. The HOMO levels could be lowered gradually by introducing sulfur, fluorine and chlorine atoms into the side chains, which contributed to the stepwise increased Voc (from 0.78 V to 0.84 V) in the related PSCs using Y6 as the electron acceptor. On the other hand, above side chain engineering strategy could promote the polymer chain interactions and fine-tune the phase separation of active blends, leading to the enhanced absorption, ordered molecular packing and crystallinity. Among them, the chlorinated PBDTCl exhibited not only high level absorption and crystallinity, but also the most balanced hole/electron charge transport and the most optimized morphology, giving rise to the best PCE of 13.46% with a Voc of 0.84 V, a Jsc of 23.16 mA cm-2 and an FF of 69.2 %. The chlorination strategy afforded PBDTCl synthetic simplicity but high efficiency, showing its promising photovoltaic applications for realizing low-cost practical PSCs in near future.
关键词： synthetic simplicity,benzodithiophene,sole donor unit,wide bandgap polymer donors,polymer solar cells
更新于2025-09-23 15:21:01
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Rational design of a novel isoindigo-based conjugated terpolymer with panchromatic absorption and its application to polymer solar cells
摘要： In this study, a panchromatic absorptive conjugated terpolymer, BDTID-BDT3MT, is synthesized, which consists of electron-donating benzodithiophene (BDT), isoindigo (ID) as a strong electron-accepting unit, and methyl-3-thiophenecarboxylate (3 MT) as a weak electron-accepting unit. By combining these three monomers into the structure of a conjugated terpolymer, the absorption spectrum of BDTID-BDT3MT is induced to exhibit an unusually broad, strong, and uniform band in the wavelength interval from 300 to 750 nm, which helps achieving highly efficient light harvesting under solar illumination. The intriguing panchromatic absorption behavior of BDTID-BDT3MT was explained on the basis of theoretical calculations using simplified repeating units. Polymer solar cells (PSCs) based on BDTID-BDT3MT as a donating polymer and non-fullerene acceptors (e.g., ITIC-4F) exhibited a high power conversion efficiency (PCE) of 5.38%, high open circuit voltage (Voc) of 0.88 V, and short circuit current density (Jsc) of 13.74 mA/cm2, while PSCs based on ternary blend systems consisting of BDTID, BDT3MT, and ITIC-4F exhibited lower PCE and Jsc of 3.74% and 11.15 mA/cm2, respectively. The superior performance of PSCs based on BDTID-BDT3MT can be attributed to their high light harvesting efficiencies and relatively more favorable nano-phase film morphologies. Our results establish that BDT, ID, and 3 MT units serve as useful building blocks in the structure of conjugated terpolymers due to their remarkably broad panchromatic absorption band.
关键词： Panchromatic absorption,Terpolymer,Benzodithiophene,Isoindigo,Polymer solar cell
更新于2025-09-23 15:21:01
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Understanding the Performance of Organic Photovoltaics under Indoor and Outdoor Conditions: Effects of Chlorination of Donor Polymers
摘要： Understanding the effects of the chemical structures of donor polymers on the photovoltaic properties of their corresponding organic photovoltaic (OPV) devices under various light-intensity conditions is important for improving the performance of these devices. We synthesized a series of copolymers based on poly[(2,6-(4,8-bis(5-(2-thioethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)] (PBDB-TS) and studied the effects of chlorine substitution of its thiophene-substituted benzodithiophene (BDT-Th) unit on its photovoltaic properties. The chlorination of the polymer resulted in a bulk heterojunction (BHJ) morphology optimized for efficient charge transport with suppressed leakage current and an increased open-circuit voltage of the OPV device; this optimization led to a remarkable enhancement of the OPV device’s power conversion efficiency (PCE) not only under the condition of 1 sun illumination but also under the condition of low light intensity mimicking indoor light; the PCE increased from 8.7% for PBDB-TS to ~13% for the chlorinated polymers, PBDT-TS-3Cl and PBDT-TS-4Cl, under the 1 sun illumination condition and from 5.3% for PBDB-TS to 21.7% for PBDB-TS-4Cl under 500 lx fluorescence illuminance. Interestingly, although the OPV PCEs under 1 sun illumination were independent of the position of chlorine substitution onto the polymer, the PBDB-TS-4Cl exhibited better performance under simulated indoor light than its derivative PBDB-TS-3Cl. Our results demonstrate that efficient light absorption and charge-carrier generation play key roles in achieving high OPV efficiency under low-light-intensity conditions.
关键词： bulk heterojunction,benzodithiophene,indoor light,chlorine substitution,organic photovoltaic
更新于2025-09-23 15:19:57
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Novel benzodithiophene type low band gap polymer solar cell application and device stability study with atomic layer deposition encapsulation technique
摘要： Novel benzodithiophene type copolymer was synthesized through a solvent evaporation technique. Poly(5-(5-(4, 8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4, 5-b’]dithiophen-2-yl)thiophen-2-yl)-2, 3-bis(3, 4-bis(decyloxy)phenyl)-8-(thiophen-2-yl) quinoxaline) (P-TQTBDT) solar cells were encapsulated with conventional and Atomic Layer Deposition (ALD) techniques. Characterizations of the samples were carried out via nuclear magnetic resonance (NMR), gel permeation chromotagraphy (GPC) and cyclic voltammetry (CV) techniques. Stability studies were carried out both P3HT and P-TQTBDT solar cells for comparison of commercial P3HT and our novel polymer solar cell. Our results con?rm that ALD is a promising technique for encapsulation of polymer solar cell since stability of P-TQTBDT improved to 72% durability from 38% durability with ALD encapsulation technique during 300 h under AM1.5 G solar irradiation. P-TQTBDT solar cell showed higher stability (about 10%) than P3HT solar cell for both encapsulation methods. We focused on the stability of polymer solar cell can be improved with ALD encapsulation technique. Our aim was to compare P-TQTBDT polymer solar cell with P3HT solar cell. The stability results of P-TQTBDT showed that P-TQTBDT copolymer could be promising polymer to obtain very high stability of polymer solar cells.
关键词： atomic layer deposition,solar cell,stability tests,ISOS stability tests,benzodithiophene,organic solar cell
更新于2025-09-23 15:19:57
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A New Benzodithiophene Based Donor-Acceptor ??-Conjugated Polymer for Organic Solar Cells
摘要： A new benzodithiophene based donor-acceptor π-conjugated polymer (P1) is designed and explored as the photoactive donor for organic solar cells (OSCs). The synthesized donor polymer, P1 displays a wide absorption profile ranging from 300-750 nm with optical band gap of 1.61 eV and moderate ionization potential of -5.30 eV. It has good solubility in non-halogenated and halogenated organic solvents. Next, we fabricated OSCs with P1 by blending with PC71BM, the pristine polymer processed from chlorobenzene showed PCE of 2.79%. Upon addition of external additive diphenyl ether to the blend showed a dramatic improvement in PCE with maximum of 5.33%. DPE tailored the active layer morphology and showed two times higher PCE than pristine films. These results clearly indicate that the new polymer has a great potentiality for enhancing efficiency upon solvent additives, which will provide new routes for the development of new class of polymers for high-performance air-stable OSCs.
关键词： benzodithiophene based π-conjugated polymer,organic solar cell,morphology,octyl side chain
更新于2025-09-23 15:19:57
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1 V high open-circuit voltage fluorinated alkoxybiphenyl side-chained benzodithiophene based photovoltaic polymers
摘要： Utilizing two-dimensional (2-D) conjugated structure and extending two-dimensional π-conjugation system with benzene can improve the performance of the BDT-based polymer solar cells (PSCs). In this work, combining with strong electron-drawing ability of fluorine atom, a new monomer BBFBDT with fluorinated alkoxybiphenyl unit as side-chain was designed and synthesized to construct medium band-gap donor (D) - acceptor (A) copolymer P1 with a benzo[1,2- c:4,5-c’]dithiophene-4,8-dione (BDD) acceptor. Blending with a classical non-fullerene acceptor ITIC, the P1-based PSCs reached a power conversion efficiency (PCE) of 4.16% and when coupled with a fullerene acceptor PC71BM, the PCE of PSCs reached 4.66% with an open-circuit voltage (Voc) of 0.93 V, a short-circuit current density (Jsc) of 9.83 mA cm?2 and a fill factor (FF) of 50.97%. The relatively poor Jsc of P1-based devices may be caused by the bad complementarity of absorption spectra. Furthermore, a wide band-gap D-A copolymer P2, with a electron-deficient 4,7-bis(5-bromothiophen-2-yl)-2-((2-ethylhexyl)oxy)-5,6-difluoro-2H-benzo[d][1,2,3]triazole (TZ) as the acceptor unit, was synthesized to match the absorption spectra of ITIC. Finally, the efficiency achieved 6.59% with Voc of 0.99 V, Jsc of 14.37 mA cm?2 and FF of 46.32%.
关键词： Fluorinated alkoxybiphenyl side-chain,Benzodithiophene (BDT),High open-circuit voltage,Conjugated polymers,Polymer solar cells
更新于2025-09-19 17:13:59
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D-A Copolymer Donor Based on Bithienyl Benzodithiophene D-unit and Monoalkoxy Bifluoroquinoxaline A-unit for High Performance Polymer Solar Cells
摘要： Molecular frontier orbital energy level and aggregation behavior regulation of polymer donors are feasible way to improve the photovoltaic performance of polymer solar cells (PSCs). Here, we design and synthesize a new D-A copolymer donor PBQ10 based on bithienyl benzodithiophene D-unit and monoalkoxy-substituted bifluoroquinoxaline A-unit, which shows obviously down-shifted highest occupied molecular orbital energy level in comparison with the control polymer PBQ7 with dialkoxyphenyl substituent on the bifluoroquinoxaline A-unit. Moreover, PBQ10 exhibits more preferential face-on molecular orientation and tighter π–π stacking in the vertical direction of substrate than that of PBQ7, which significantly improves the hole mobility of PBQ10 to 5.22×10-4 cm2 V-1 s-1 in comparison with that (1.71×10-4 cm2 V-1 s-1) of PBQ7. As a result, the PBQ10-based PSC with Y6 as acceptor demonstrates an impressive power conversion efficiency (PCE) of 16.34 % with simultaneously increased open circuit voltage and fill factor, which is significantly increased than the PBQ7-based PSC with PCE of 13.45 %, and is one of the highest PCEs in binary PSCs. The result suggests that rational side chain optimization of polymer donor is an efficient way to regulate molecular energy level and self-assembly feature, thus to improve the PCE of PSCs.
关键词： Power conversion efficiency,Polymer solar cells,Bithienyl benzodithiophene,Monoalkoxy-substituted bifluoroquinoxaline,D-A copolymer donor
更新于2025-09-19 17:13:59
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Highly Efficient Large Area Organic Photovoltaic Module with 350 nm Thick Active Layer using Random Terpolymer Donor
摘要： Random terpolymers are developed by incorporating small portions of benzodithiophene into a highly crystalline copolymer of terthiophene and difluorobenzothiadiazole, BDT-Th0. The bulk-heterojunction (BHJ) of the copolymer BDT-Th0 is formed by process of rapid solid-liquid phase demixing of polymer crystallites, which results in irregular and unclear phase separation with large polymer aggregation. By contrast, the random terpolymer BDT-Th10 which was prepared using 10% feed molar ratio of a benzodithiophene moiety shows slower and gradual formation of the polymer packing structures without substantial agglomeration from loosely packed pseudo-crystallites in precursor solution. This results in optimal BHJ morphology with appropriate phase separation and improved domain purity. BDT-Th10 achieves high solar cell efficiency of 7.74% by successfully reproducing the optimized BHJ morphology of small cells into 58.5 cm2 sized modules with 350 nm film thickness, whereas the copolymer shows irreproducible property with much decreased efficiency of 4.37%. This result is among the highest efficiency of high-performance large area PSC modules with such a thick active film.
关键词： Random terpolymers,benzodithiophene,bulk-heterojunction,large area modules,polymer solar cells
更新于2025-09-19 17:13:59