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Organic solar cells based on chlorine functionalized benzo[1,2-b:4,5-ba?2]difuran-benzo[1,2-c:4,5-ca?2]dithiophene-4,8-dione copolymer with efficiency exceeding 13%
摘要： Benzo[1,2-b:4,5-b′]dithiophene (BDT) has been widely used to construct donor-acceptor (D-A) copolymers in organic solar cells (OSCs). However, benzo[1,2-b:4,5-b′]difuran (BDF), an analogue of BDT, has received less attention than BDT. The photovoltaic performance of BDF copolymers has lagged behind that of BDT copolymers. Here, we designed and synthesized two BDF copolymers, PBF1-C and PBF1-C-2Cl. PBF1-C-2Cl, which is composed of BDF and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione connected by a chlorinated thiophene π-bridge, displays a low-lying highest occupied molecular orbital energy level, which helps in yielding a high open-circuit voltage (Voc) in OSCs. As a result, when blended with Y6, PBF1-C-2Cl-based devices showed a high Voc of 0.83 V and a power conversion efficiency (PCE) of 13.10%. To the best of our knowledge, the PCE of 13.10% is among the highest efficiency values for OSCs based on BDF copolymers.
关键词： chlorinated thiophene,π-bridge,benzo[1,2-c:4,5-c′]dithiophene-4,8-dione,benzo[1,2-b:4,5-b′]difuran,organic solar cells
更新于2025-09-19 17:13:59
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Asymmetrical side-chain engineering of small-molecule acceptors enable high-performance nonfullerene organic solar cells
摘要： Three new small molecules based on the benzo[1,2-b:4,5-b’]dithiophene (BDT) fused central core with different side-chains, namely DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl, are designed and synthesized to investigate the side-chain effect on the properties of nonfullerene acceptors. DPBDT-4Cl has symmetrical phenylalkyl side-chains on the central BDT unit. In order to narrow the bandgap and reduce the steric hindrance, the phenylalkyl chains are systematically replaced with the flexible electron-donating alkoxy side-chain (POBDT-4Cl) and alkyl side-chain (COBDT-4Cl). As a result, POBDT-4Cl and COBDT-4Cl are characterized with asymmetry-featured side-chains. From DPBDT-4Cl to POBDT-4Cl to COBDT-4Cl, their light absorption abilities, molecular packing behaviors and crystallinity are gradually enhanced. The devices based on these three acceptors all show power conversion efficiencies (PCEs) over 11% with energy loss below 0.55 eV. Compared to DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl obviously exhibit enhanced device performance with improved short-circuit current densities (Jsc) and fill factors (FFs), which mainly ascribe to their reduced charge recombination and enhanced charge transport. In addition, the COBDT-4Cl achieved a high efficiency of 13.5% with a Jsc of 21.8 mA cm-2 and an FF of 0.71. This result is among the best performance obtained from asymmetry-featured small molecules.
关键词： side-chains,benzo[1,2-b:4,5-b’]dithiophene,small-molecule acceptors,asymmetrical
更新于2025-09-19 17:13:59
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Non‐Fullerene Organic Solar Cells Based on Benzo[1,2‐b:4,5‐b′]difuran‐Conjugated Polymer with 14% Efficiency
摘要： The development of high-performance donor polymers is important for obtaining high power conversion efficiencies (PCEs) of non-fullerene polymer solar cells (PSCs). Currently, most high-efficiency PSCs are fabricated with benzo[1,2-b:4,5-b′]dithiophene (BDT)-based conjugated polymers. The photovoltaic performance of benzo[1,2-b:4,5-b′]difuran (BDF)-based copolymers has lagged far behind that of BDT-based counterparts. In this study, a novel BDF-based copolymer L2 is designed and synthesized, in which BDF and benzotriazole (BTz) building blocks have been used as the electron-sufficient and deficient units, respectively. When blending with a non-fullerene small molecule acceptor (SMA), TTPT-T-4F, the L2-based device exhibits a remarkably high PCE of 14.0%, which is higher than that of the device fabricated by its analogue BDT copolymer (12.72%). Moreover, PSCs based on the L2:TTPT-T-4F blend demonstrate excellent ambient stability with 92% of its original PCE remaining after storage in air for 1800 h. Thus, BDF is a promising electron-donating unit, and the BDF-based copolymers can be competitive or even surpass the performance of BDT-based counterparts.
关键词： ambient stability,copolymer,organic solar cells,power conversion efficiency,benzo[1,2-b:4,5-b′]difuran
更新于2025-09-16 10:30:52
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Effect of Fluorination on the D-A-D type Hole Transporting Materials for Perovskite Solar Cells
摘要： To study the effect of fluorination on hole transporting materials (BTD-Th and BTD-F-Th) for the efficient perovskite solar cells, we designed and synthesized a novel D-A-D type hole transporting molecule having benzo[1,2-c][1,2,5]thiadiazole (BTD) as electron acceptor unit and thiophene (Th) as a simple electron donor unit. The D-A-D molecules BTD-Th and BTD-F-Th were synthesized by palladium(0) catalyzed Stille coupling reaction. The electrochemical band gap of synthesized compounds varies from -1.5 eV to -1.7 eV, Which were ideal for hole transport material (with perovskite active layer) and effective electron blocking layer. The architecture of the perovskite device is glass/ITO/SnO2/CH3NH3PbI3(Perovskite)/Hole Transport Material/Ag.
关键词： Perovskite,benzo[1,2-c][1,2,5]thiadiazole,thiophene,hole transporting materials
更新于2025-09-16 10:30:52
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Synthesis and Photovoltaic Effect of Electron-Withdrawing Units for Low Band Gap Conjugated Polymers Bearing Bi(thienylenevinylene) Side Chains
摘要： A novel (E)-5-(2-(5-alkylthiothiophen-2-yl)vinyl)thien-2-yl (TVT)-comprising benzo[1,2-b:4,5-b’]dithiophene (BDT) derivative (BDT-TVT) was designed and synthetized to compose two donor-acceptor (D-A) typed copolymers (PBDT-TVT-ID and PBDT-TVT-DTNT) with the electron-withdrawing unit isoindigo (ID) and naphtho[1,2-c:5,6-c’]bis[1,2,5]thiadiazole (NT), respectively. PBDT-TVT-ID and PBDT-TVT-DTNT showed good thermal stability (360 °C), an absorption spectrum from 300 nm to 760 nm and a relatively low lying energy level of Highest Occupied Molecular Orbital (EHOMO) (?5.36 to –5.45 eV), which could obtain a large open-circuit voltage (Voc) from photovoltaic devices with PBDT-TVT-ID or PBDT-TVT-DTNT. The photovoltaic devices with ITO/PFN/polymers: PC71BM/MoO3/Ag structure were assembled and exhibited a good photovoltaic performance with a power conversion efficiency (PCE) of 4.09% (PBDT-TVT-ID) and 5.44% (PBDT-TVT-DTNT), respectively. The best PCE of a PBDT-TVT-DTNT/PC71BM-based device mainly originated from its wider absorption, higher hole mobility and favorable photoactive layer morphology.
关键词： polymer solar cells,photovoltaic property,benzo[1,2-b:4,5-b’]dithiophene,low band gap,bi(thienylenevinylene)
更新于2025-09-11 14:15:04
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The photophysical properties and electronic structures of bis[1]benzothieno[6,7-d:6',7'-d']benzo[1,2-b:4,5-b']dithiophene (BBTBDT) derivatives as hole-transporting for organic light-emitting diodes (OLEDs)
摘要： By using the quantum methods DFT and TD-DFT in this paper, the optoelectronic properties and electronic structures of eight compounds Ci (i=1-8) based on bis[1]benzothieno[6,7-d:6',7'-d']benzo[1,2-b:4,5-b']dithiophene (BBTBDT) with D-π-D structure for Ci (i=1-5); and D-π-A for Ci (i=6-8) have been calculated and discussed theoretically in the aim to consider them as hole-transporting materials (HTM) in OLEDs. The calculated electronic levels by B3LYP of studied compounds show that the proper energy of Ci (i=6-8) is so matching for efficiency injecting into hole-injection layer (HIL). The compounds having D-π-A structure seem more efficient than those having D-π-D structure. The optoelectronic properties for studied compounds obtained by TD-CAM-B3LYP elucidate that C6, C7 and C8 compounds behave as electron donating molecules and induce charge transfer character in the UV-visible absorptions and emission electronic spectra. Furthermore, the calculated reorganization energies, ionization potential (IP) and electron affinity (EA) also provide that the extended C6, C7 and C8 compounds have the highest charge-transporting ability among all compounds. It is found that the D-π-A more influence on the electronic and optoelectronic properties than the D-π-D structure. The assumed compound C7 is found to be a good candidate for blue-emitting material. Understanding these properties is important to design HTMs with exceptional properties, such as stability and high efficiency.
关键词： B3LYP,DFT,bis[1]benzothieno[6,7-d:6',7'-d']benzo[1,2-b:4,5-b']dithiophene (BBTBDT),OLEDs
更新于2025-09-11 14:15:04
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Bicomponent-random Approach to Synthesis of Donor Polymers for Efficient All-Polymer Solar Cells Processed from A Green Solvent
摘要： All-polymer solar cells (all-PSCs) can offer unique merits of high morphological stability to thermal and mechanical stress. To realize its full potential as flexible or wearable devices, it is highly desirable that the all-PSCs can be fabricated from green solvent with simple post-treatment to avoid thermal annealing on flexible substrate. This proposed a severely challenge on material design to tune their properties with suitable solubility, aggregation, and morphology. To address this challenge, here, a simple bicomponent-random approach on a D-A-type polymer donor was developed by just varying the D-A molar ratio. Under this approach, a series of new random polymers PBDTa-TPDb with different molar ratio of D component of 2D-benzo[1,2-b:4,5-b']dithiophene (BDT) and A component of thieno[3,4-c]pyrrole-4,6-dione (TPD) were designed and synthesized. The energy levels, light absorption, solubility and packing structure of random donors PBDTa-TPDb were found to vary substantially with the various D-A molar ratio. The devices based PBDTa-TPDb/P(NDI2HD-T) were fabricated to explore the synergistic effects of processing solvent and composition of D-A-type random polymers. The results show that nanoscale morphology, balanced miscibility/crystallinity of blend and photovoltaic properties could be rationally optimized by tuning the composition of random donors. As a result, as-cast all-PSC based optimal donor PBDT5-TPD4 achieves a best power conversion efficiency (PCE) of 8.20% processed from green solvent, which performs better than that based reference polymer (PCE: 6.41%). This efficiency is the highest value for all-PSCs from BDT-TPD-based donors. Moreover, the optimized devices exhibited relatively insensitive to the thickness of the active layer and good stability.
关键词： thieno[3,4-c]pyrrole-4,6-dione,all-polymer solar cells,bicomponent-random approach,benzo[1,2-b:4,5-b']dithiophene,green solvent
更新于2025-09-11 14:15:04