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Novel Small Four-armed Molecules with Triphenylamine-bridged Structure for Organic Solar Cells Featuring High Open-circuit Voltage
摘要： In view of few attention on star-shaped molecules containing triphenylamine(TPA) unit as π-linker, a series of small four-armed molecules, consisting of octyloxy-substituted 2,1,3-benzothiadiazole(DOBT) or 4-octyl-2-thienyl functionalized DOBT as the core, TPA as π-bridge and 4-methylphenyl or 4-methoxyphenyl groups as terminal units, was designed and synthesized. The effects of π-bridges and substitute groups on molecular photoelectric performance and photovoltaic performance were fully explored. With the help of the additional thiophene-linkers incorporation, 3-octylthienyl substituted molecule with end-capping 4-methylphenyl(T-BTTPAM) and 3-octylthienyl substituted molecule with end-capping 4-methoxyphenyl(T-BTTPAOM) showed stronger and broader absorption, as well as higher charge mobilities compared to the molecules without thiophene-linkers(BTTPAM and BTTPAOM). Additionally, changing substitute groups from methyl to methoxy helped BTTPAOM and T-BTTPAOM achieve better absorption properties than BTTPAM and T-BTTPAM, respectively. When paired with PC61BM as the electron acceptor to fabricate solution-processed photovoltaic devices, the four materials gave high open-circuit voltage(Voc) values over 0.90 V. These results demonstrate that our materials are promising candidates as donor materials for organic solar cells(OSCs), and further device optimization is in progress in our laboratory.
关键词： Organic solar cell,Triphenylamine,Four-armed structure,High open-circuit voltage,Small-molecule donor
更新于2025-09-16 10:30:52
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Highly-Crystalline Near-Infrared Acceptor Enabling Simultaneous Efficiency and Photostability Boosting in High-Performance Ternary Organic Solar Cells
摘要： The near-infrared (NIR) absorbing fused-ring electron acceptor, COi8DFIC, has demonstrated very good photovoltaic performance when combined with PTB7-Th as donor in binary organic solar cells (OSCs). In this work, the NIR acceptor was added to state-of-the art PBDB-T-2F:IT-4F-based solar cells as a third component, leading to: (i) an efficiency increase of the ternary devices compared to the binary solar cells in the presence of the highly-crystalline COi8DFIC acceptor and (ii) much improved photostability under 1-sun illumination. The electron transport properties were investigated and revealed the origin of the enhanced device performance. Compared to the binary cells, the optimized ternary PBDB-T-2F:COi8DFIC:IT-4F blends exhibit improved electron transport properties in the presence of 10% COi8DFIC, which is attributed to improved COi8DFIC molecular packing. Furthermore, transient absorption spectroscopy revealed slow recombination of charge carriers in the ternary blend. The improved electron transport properties were preserved in the ternary OSC upon aging, while in the binary devices they seriously deteriorated after simulated 1-sun illumination of 240 hours. Our work demonstrates a simple approach to enhance both OSC efficiency and photostability.
关键词： near-infrared acceptor,organic solar cell,ternary solar cell,photostability
更新于2025-09-12 10:27:22
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Mechanism of Organic Solar Cell Performance Degradation upon Thermal Annealing of MoO <sub/>x</sub>
摘要： In this work we focus on P3HT:PC61BM bulk heterojunction (BHJ) devices with MoO3 at the hole extraction side of the BHJ which relies on the formation of a strong dipole at the BHJ/MoO3 interface, as a reference system that has been extensively studied. We have observed depending on when the annealing is performed during device fabrication, device performance either increased or decreased due to formation of a sharp or relatively diffuse interface respectively due to diffusion of MoOx into the BHJ. The measured strength of the dipole at this interface following thermal annealing correlated well with the width of the interface and device performance, with the sharper interface resulting in a stronger dipole and in improved device performance. This is expected to be a general phenomenon for evaporated coatings onto polymeric BHJ, regardless of the polymers involved.
关键词： Organic solar cell,Interface dipole,MoO3,Thermal annealing,Energy level alignment
更新于2025-09-12 10:27:22
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Charge photogeneration and recombination in single-material organic solar cells and photodetectors based on conjugated star-shaped donor-acceptor oligomers
摘要： Single-material organic solar cells (SMOSC) are attracted by their simple structure and ease of fabrication so that they are virtually free from a number of drawbacks of heterojunction organic solar cells. However, the performance of SMOSC is still low, first of all because of poor understanding of losses on the way of energy conversion from light to electricity. In this work, we present solution-processed SMOSC based on star-shaped π-conjugated donor-acceptor oligomers with triphenylamine donor (N-Ph3) and alkyl- or phenyl dicyanovinyl acceptor (DCV-R) of general formulae N(Ph-nT-DCV-R)3, where nT stands for n-oligothiophene, and study charge photogeneration and recombination in them. SMOSC demonstrate small energy losses resulting in high open-circuit voltage of 1.08 – 1.19 V and the power conversion efficiency up to 1.22% under illumination intensity of 0.45 sun (1.13% under one sun) with the maximum external quantum efficiency up to 24% for N(Ph-2T-DCV-Ethyl)3, which are among the highest for SMOSC based on conjugated donor-acceptor small molecules or oligomers. It was found that monomolecular recombination dominates at the short-circuit condition and the maximum power point, but at the open-circuit condition the photoinduced charges recombine nearly bimolecularly. The bottleneck in the SMOSC performance was shown to be the field-assisted charge generation perfectly described by the Onsager model in the limit of weak electric fields. The results obtained suggest that intermolecular charge delocalization in conjugated donor-acceptor molecules would be beneficial for further progress in SMOSC.
关键词： conjugated molecule,charge recombination,donor-acceptor molecule,Onsager model,organic solar cell,charge generation
更新于2025-09-12 10:27:22
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Size-dependent instability of organic solar cell resting on Winkler-Pasternak elastic foundation based on the modified strain gradient theory
摘要： The present study employs the modified strain gradient theory (MSGT) in conjunction with the refined shear deformation plate theory to explore the buckling behaviour of simply supported and clamped OSC. The Winkler-Pasternak elastic foundation is implemented to idealise the foundation. The size-dependent effect of the OSC is captured by the three length scale parameters within the MSGT. The Hamilton principle is used to derive the equations of motion and the boundary conditions, and the Galerkin procedure is subsequently implemented to obtain the critical buckling load. Subsequently, the framework is extended to the thermally induced buckling behaviour, and three types of temperature rise patterns, namely uniform, linear and nonlinear temperature variations, along the thickness of the OSC are considered. Several verification studies are conducted to illustrate the accuracy of the present method. Besides, size-dependent material properties are taken into consideration during the numerical experiments. Thorough studies are conducted to demonstrate the difference between critical buckling loads and temperature variations obtained from the MSGT, the modified couple stress theory (MCST), and the classical plate theory (CPT) models. Furthermore, the effects of length scale parameter (hl), the aspect ratio (ab), the length-to-thickness ratio (ah) and the Winkler-Pasternak elastic foundation parameters on the buckling behaviour of the OSC are also revealed by the numerical results.
关键词： Refined shear deformation plate theory,Strain gradient elasticity theory,Thermal buckling,Organic solar cell,Mechanical buckling,Elastic foundation
更新于2025-09-12 10:27:22
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Spray deposited indium doped tin oxide thin films for organic solar cell application
摘要： Highly conducting and transparent undoped and indium doped tin oxide (SnO2:In) thin films are prepared by spray technique at different doping concentration of Indium (In). The X-ray diffraction pattern of SnO2:In thin films are confirmed the tetragonal phase of SnO2. The resistivity of SnO2:In film is increased with increased the doping concentration of In due to the effect of ionized impurity and intragrain scattering mobility. The optimized (SnO2:In) thin film is used as a photo anode in the organic solar cells (OSC) of configuration of SnO2:In/PDOT:PSS/P3HT:PCBM/Al. The photo conversion efficiency of OSC is obtained 1.06 % for SnO2 layer and it was observed 0.56% for In doped SnO2 based photoanode.
关键词： Spray technique,Indium doped tin oxide,Organic solar cell
更新于2025-09-12 10:27:22
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Passivated metal oxide n-type contacts for efficient and stable organic solar cells
摘要： Suppressing trap states and localized electronic states in the forbidden gap of semiconductors as either active layers or contacts, is critical to the enhancement of optoelectronic device performance, such as solar cell, ultra-fast photodetectors, field-effect transistors as well as other optoelectronic applications. In this study, we demonstrate Lewis bases-passivated metal oxide n-type contacts can effectively improve the performance of organic solar cells (OSCs). OSCs with triethanolamine-passivated ZnO show two orders of magnitude lower trap density, and thus higher electron mobility and three times longer charge carrier recombination lifetime, relative to the devices based on as-cast ZnO. Passivated ZnO universally improves power conversion efficiency (PCE) of OSCs based on varied active layers. P3HT: PC71BM based solar cells with passivated-ZnO yield 86% PCE enhancement relative to the control devices based on as-cast ZnO, and PM6: Y6 based devices with passivated-ZnO exhibit PCEs up to 15.61%. Furthermore, light stability of OSCs with passivated-ZnO has also been improved along with enhanced device efficiency. Lewis base is also efficient to passivate SnOX contact for solar cells. This study highlights the importance of defect passivation on contact layers for improvement of the efficiency and stability of OSCs, and also provides one facile and effective passivation strategy.
关键词： defect passivation,electron transport layer,organic solar cell,tin oxide,zinc oxide
更新于2025-09-12 10:27:22
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Enhancing the Power Conversion Efficiency of Organic Solar Cells
摘要： Organic solar cells (OSCs) have significantly reduced the overall cost of solar energy system, making solar oriented devices universally clean and green energy source. However, to make OSCs more competitive in diverse photovoltaic (PV) technologies, it is essential to attain high efficiencies by analyzing novel materials and realizing optimal arrangements of donor–acceptor materials. In this paper, we attempt to show a terse depth insight of OSCs by investigating three novel architecture schemes with special emphasis on improving the power conversion efficiency. The materials include include i) poly (3-hexylthiophene):[(6,6)]-phenyl C61 butyric acid methyl ester (P3HT:PCBM), ii) thieno [3,4-b] thiophene-alt-benzodithiophene:[6,6]-phenyl-C61 butyric acid methyl ester (PTB7:PCBM), and iii) poly{4,4′-bis(2-ethylhexyl) dithieno [3,2-b:2′,3′-d] silole-alt-5,6-difluoro-4,7-bis (4-hexylthiophen-2-yl)-2,1,3-benzothiadiazle):[6,6]-phenyl-C61 butyric acid methyl ester (PDTS-DTffBT:PCBM), respectively. Results show that the extracted performance parameters including short circuit current (JSC) = 10.88 mA/m2, open circuit voltage (Voc) = 0.82 V, fill factor (FF) = 83.52%, and efficiency (?) = 7.49% is highest for the second scheme among others. Different intermediate layers have also been analyzed with the objective to reduce the recombination losses and enhance the power conversion efficiency of the proposed cell. The impact of temperature on the overall ? is also presented and it is discovered that high temperature reduces the performance of the solar cell. Furthermore, the performance of the proposed structure is compared with various kinds of OSCs and it is found that our design exhibit highest efficiency. The achievement of high efficiencies in this work may accelerate the practical applications of OSCs.
关键词： interfacial layer,absorber materials,Organic solar cell,and efficiency.
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Alternative approach to optimizing optical spacer layer thickness in solar cell using evolutionary algorithm
摘要： This work is inspired by Darwin's biological evolution theory: natural selection. We propose to use genetic evolutionary algorithm to optimize the search for the optimal thickness in solar cells with regards to maximizing short-circuit current density. Optical spacer layer thickness need to be optimized in order to achieve maximum absorption of the incoming light by the solar cell. In order to obtain the best optical spacer thickness, we perform multiple simulations with different number of population, number of generations, mutation probability, number of bits, and selection and crossover methods. Our preliminary experiments show that the introduction of evolutionary algorithm result in a satisfactorily accurate search method when compared to brute-force. The future works on utilizing the full ability of evolutionary algorithm will be presented at the conference.
关键词： finite difference time domain,evolutionary algorithm,organic solar cell,optical modelling
更新于2025-09-12 10:27:22
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BODIPY Substituted Zinc(II) Phthalocyanine and Its Bulk Heterojunction Application in the solar cells
摘要： A novel asymmetrical zinc(II) phthalocyanine-BODIPY conjugate (ZnPc-BODIPY) bearing three iodine directly substituted to the macrocycle and one BODIPY connected to macrocycle with amide bond was synthesized by the reaction of carboxylic acid substituted asymmetrical zinc(II) phthalocyanine (ZnPc) with BODIPY derivative bearing amino group (BODIPY-NH2). This conjugate was fully characterized by spectroscopic methods (FT-IR, UV-Vis, 1H NMR, 11B NMR, 19F NMR and mass) and elemental analysis. The fluorescence behavior of ZnPc-BODIPY was studied for determination of energy transfer process. The voltammetry measurements (CV and SWV) were performed for specifying of the HOMO-LUMO energy levels and band gaps of ZnPc-BODIPY and starting compounds ZnPc and BODIPY-NH2 for comparison. In addition, the band gaps of these compounds were also determined by UV-Vis absorption onset (λonset) and theoretical calculations. Bulk heterojunction solar cell containing ZnPc-BODIPY were fabricated in the structure of ITO/PEDOT:PSS/ZnPc-BODIPY:PCBM/Al. The photovoltaic parameters of the solar cell were obtained and ZnPc-BODIPY conjugate was found to bring spectral contribution to IPCE at a peak of 510 nm.
关键词： BODIPY,Organic solar cell,Suzuki coupling,Phthalocyanine
更新于2025-09-12 10:27:22