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Efficiency enhancement of small molecule organic solar cells using hexapropyltruxene as an interface layer
摘要： The quenching of excitons in organic solar cells can play a significant role in limiting their power conversion efficiency (PCE). In this article, we investigate the effect of a thin layer of hexapropyltruxene inserted at the interface between the electron donor boron subphthalocyanine chloride (SubPc) and its underlying hole contact in planar heterojunction solar cells. We find that a 3.8 nm hexapropyltruxene interlayer between the molybdenum oxide (MoOx) hole contact and SubPc is sufficient to improve PCE in SubPc/C60 fullerene solar cells from 2.6 % to 3.0 %, a ～20 % performance improvement. While the absorption stays roughly the same, the comparison of external and internal quantum efficiencies reveals a significant increase in SubPc’s contribution to the current for light with wavelengths between 520 and 600 nm. Microstructure and surface morphology assessed with in-situ Grazing-Incidence Wide-Angle X-Ray Scattering (GIWAXS) and Atomic Force Microscopy (AFM), are evaluated alongside in-situ spectroscopic ellipsometry, and photoluminescence measurements. The microstructural investigations demonstrate changes to the surface and bulk of SubPc grown atop a hexapropyltruxene interlayer indicating that the latter acts as a template layer in a similar way as MoOx. However, the improvement in PCE is found to be mainly via reduced exciton quenching at the MoOx contact with the insertion of the hexapropyltruxene layer.
关键词： hexapropyltruxene,power conversion efficiency,exciton quenching,organic solar cells,SubPc/C60
更新于2025-09-16 10:30:52
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Importance of interfacial crystallinity to reduce open-circuit voltage loss in organic solar cells
摘要： Reducing the energy loss in output voltage is critically important for further enhancing the ef?ciency of organic solar cells (OSCs). Here, we report that OSCs with high mobility and highly crystalline donor (D) and acceptor (A) materials were able to reduce an open-circuit voltage (VOC) loss. The crystallinity of the acceptor layer could be altered by appropriate selection of the three molecules with different alkyl side chain lengths. The VOC was found to increase as the crystallinity of the acceptor layer increased. The origin of the high VOC was that the highly crystalline D/A interface reduced the energy loss in the output voltage by realizing ideal band-to-band recombination. Especially, the high crystallinity of the several molecular layers (less than 6 nm) in the vicinity of the D/A interface was important for realizing the high VOC. Our results demonstrate that the careful design of the D/A interface enables high power conversion ef?ciencies to be achieved in OSCs by reducing open-circuit voltage loss.
关键词： power conversion efficiency,interfacial crystallinity,open-circuit voltage loss,organic solar cells,donor/acceptor interface
更新于2025-09-16 10:30:52
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Simultaneous enhanced efficiency and thermal stability in organic solar cells from a polymer acceptor additive
摘要： The thermal stability of organic solar cells is critical for practical applications of this emerging technology. Thus, effective approaches and strategies need to be found to alleviate their inherent thermal instability. Here, we show a polymer acceptor-doping general strategy and report a thermally stable bulk heterojunction photovoltaic system, which exhibits an improved power conversion efficiency of 15.10%. Supported by statistical analyses of device degradation data, and morphological characteristics and physical mechanisms study, this polymer-doping blend shows a longer lifetime, nearly keeping its efficiency (t = 800 h) under accelerated aging tests at 150 oC. Further analysis of the degradation behaviors indicates a bright future of this system in outer space applications. Notably, the use of polymer acceptor as a dual function additive in the other four photovoltaic systems was also confirmed, demonstrating the good generality of this polymer-doping strategy.
关键词： polymer acceptor,power conversion efficiency,bulk heterojunction,organic solar cells,thermal stability
更新于2025-09-16 10:30:52
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Cyclooctatetrathiophene-Cored Three-Dimensional Hole Transport Material Enabling Over 19% Efficiency of Perovskite Solar Cells
摘要： In this work, a rigid three-dimensional cyclooctatetrathiophene was the core component in the construction two hole transporting materials (HTMs), COTT-1 and COTT-2. Their photophysical, electrochemical and thermal properties were systematically investigated in a combination of experimental and simulation methods. COTT-1 and COTT-2 based perovskite solar cells (PSCs) were tested, exhibiting power conversion efficiency (PCE) of 8.4% and 17.7%, respectively, which are similar to Spiro-OMeTAD-based device (18.2%) under the same conditions. PCE was further increased to 19.2% using COTT-1 as an interfacial layer and COTT-2 as HTM. These phenomena were analyzed by means of photoluminescence (PL), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscope experiments (AFM), which demonstrated the potential of cyclooctatetrathiophene-cored hole transport material.
关键词： power conversion efficiency,interfacial modification,thiophene,perovskite solar cells,hole transport material,three dimension
更新于2025-09-16 10:30:52
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A Random Polymer Donor for High-Performance Polymer Solar Cells with Efficiency Over 14%
摘要： Constructing random copolymers has been regarded as an easy and effective approach to design polymer donors for state-of-the-art polymer solar cells (PSCs). In this work, we develop a naphtho[2,3-c]thiophene-4,9-dione (NTDO) based copolymer PBN-Cl as a donor material for PSC, and a moderate power conversion efficiency (PCE) of 11.21% is achieved with a relatively low fill factor (FF) of 0.615. We then incorporate a similar acceptor unit benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD) into the polymeric backbone of PBN-Cl to tune its photovoltaic performance, and a significantly higher PCE of 14.05% is achieved from the random polymer PBN-Cl-B80 containing 80% BDD unit. The enhanced PCE of the PBN-Cl-B80-based device mainly relies on the higher FF value, resulting from the improved charge mobility properties, reduced bimolecular and trap-assisted recombination, and more appropriate phase separation. The results demonstrate a feasible strategy to tune the photovoltaic performance of polymer donors by constructing random polymer with a compatible component.
关键词： polymer solar cells,power conversion efficiency,random polymer,fill factor,charge-carrier mobility,polymer donor
更新于2025-09-16 10:30:52
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Dual-source Co-evaporation of Low-bandgap FA <sub/>1-x</sub> Cs <sub/>x</sub> Sn <sub/>1-y</sub> Pb <sub/>y</sub> I <sub/>3</sub> Perovskites for Photovoltaics
摘要： Perovskite halides are well-suited to monolithic multijunction photovoltaics, promising low cost solar-to-electrical power conversion. Critical to all-perovskite multijunction fabrication is the deposition of a low-bandgap absorber without damaging other device layers. Vapour deposition is thus an attractive method, obviating the need for optically lossy protective interlayers, but is challenging for multi-component perovskites. Here, we demonstrate a method to dual-source co-evaporate low-bandgap perovskite films and devices. We used mixtures formed by melting of metal halides as a single-crucible source of Cs, Pb, and Sn cations. Surprisingly, when this melt was co-evaporated with formamidinium iodide (FAI), uniform and dense perovskite films in the family FA1-xCsxSn1-yPbyI3 were formed. Inclusion of SnF2 in the melt helped to regulate the perovskite’s optoelectronic quality leading to a steady-state power conversion efficiency of ~10% in a solar cell. This represents a new processing paradigm for evaporated perovskite alloys, which is an important step towards all-perovskite multijunction photovoltaics.
关键词： power conversion efficiency,perovskite halides,low-bandgap absorber,SnF2,vapour deposition,formamidinium iodide,multijunction photovoltaics
更新于2025-09-16 10:30:52
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Tuning the electronic, optical and structural properties of GaS/C2N van der Waals heterostructure for photovoltaic application: first-principle calculations
摘要： Due to the increased energy demand, a large amount of renewable energy is required to sustain the lives of people. The visible light semiconductors for photovoltaic cells with optical properties and a tunable bandgap have been studied to bring the solution to energy crises. Two-dimensional (2D) semiconductors including gallium sulphide (GaS) and carbon nitride (C2N) monolayers as a photovoltaic material were investigated by designing GaS/C2N van der Waals (vdWs) heterostructure. In this study, density functional theory (DFT) was employed to study the structural, photovoltaic applications, electronic and optical properties of GaS/C2N vdWs heterostructure. In comparison with the counterparts of GaS and C2N monolayers, the GaS/C2N vdWs heterostructure showed a lower desirable direct bandgap of 1.251 eV and the projected density of states shows a type-I band alignment. The work function of the heterostructure is much lesser than the GaS monolayer and C2N layer, which signifies that less energy will be needed for electrons to transfer from the ground state. The charge density transfer shows charge redistribution from GaS to C2N. The power conversion efficiency (η) of GaS/C2N heterostructure is calculated to be 17.8%. Based on the results, the 2D GaS/C2N heterostructure is predicted to be effective material in developing a high-performance photovoltaic device for future use.
关键词： Density functional theory,Heterostructure,Power conversion efficiency,Photovoltaic cells
更新于2025-09-16 10:30:52
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Precursor Engineering for Large-area Perovskite Solar Cell with >19% Efficiency
摘要： Here, we report on precursor engineering for a large-area perovskite film using an air-knife assisted D-bar coater. Lead acetate (PbAc2) is stoichiometrically added in the mother solution consisting of methylammonium iodide (MAI) and lead iodide (PbI2) in 2-methoxyethanol (2ME), leading to MAPbI3 and by-product methylammonium acetate (MAAc). Crystal growth can be controlled in the presence of MAAc while drying the wet film. The average power conversion efficiency (PCE) of 15.14% is achieved, whereas the quality of perovskite film is uncontrollable in the absence of PbAc2 resulting in a PCE as low as 2.63%. Carrier life time is further improved by about 46% when incorporating 0.12 mol% guanidinium iodide (GAI) in the PbAc2-contained precursor solution, which demonstrates a PCE of 19.44% with a device employing a piece of the large-area perovskite film (~46 cm2) and a PCE of 13.85% with a module with an active area of 16 cm2.
关键词： guanidinium iodide,precursor engineering,perovskite solar cells,large-area coating,power conversion efficiency
更新于2025-09-12 10:27:22
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Subtle Molecular Tailoring Induces Significant Morphology Optimization Enabling over 16% Efficiency Organic Solar Cells with Efficient Charge Generation
摘要： Manipulating charge generation in a broad spectral region has proved to be crucial for nonfullerene-electron-acceptor-based organic solar cells (OSCs). 16.64% high efficiency binary OSCs are achieved through the use of a novel electron acceptor AQx-2 with quinoxaline-containing fused core and PBDB-TF as donor. The significant increase in photovoltaic performance of AQx-2 based devices is obtained merely by a subtle tailoring in molecular structure of its analogue AQx-1. Combining the detailed morphology and transient absorption spectroscopy analyses, a good structure–morphology–property relationship is established. The stronger π–π interaction results in efficient electron hopping and balanced electron and hole mobilities attributed to good charge transport. Moreover, the reduced phase separation morphology of AQx-2-based bulk heterojunction blend boosts hole transfer and suppresses geminate recombination. Such success in molecule design and precise morphology optimization may lead to next-generation high-performance OSCs.
关键词： solar cell morphology,organic solar cells,power conversion efficiency,nonfullerene acceptors,charge generation
更新于2025-09-12 10:27:22
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Zwitterion Nondetergent Sulfobetaine-Modified SnO <sub/>2</sub> as an Efficient Electron Transport Layer for Inverted Organic Solar Cells
摘要： Tin oxide (SnO2) has been widely accepted as an effective electron transport layer (ETL) for optoelectronic devices because of its outstanding electro-optical properties such as its suitable band energy levels, high electron mobility, and high transparency. Here, we report a simple but effective interfacial engineering strategy to achieve highly efficient and stable inverted organic solar cells (iOSCs) via a low-temperature solution process and an SnO2 ETL modified by zwitterion nondetergent sulfobetaine 3-(4-tert-butyl-1-pyridinio)-1-propanesulfonate (NDSB-256-4T). We found that NDSB-256-4T helps reduce the work function of SnO2, resulting in more efficient electron extraction and transport to the cathode of iOSCs. NDSB-256-4T also passivates the defects in SnO2, which serves as recombination centers that greatly reduce the device performance of iOSCs. In addition, NDSB-256-4T provides the better interfacial contact between SnO2 and the active layer. Thus, a higher power conversion efficiency (PCE) and longer device stability of iOSCs are expected for a combination of SnO2 and NDSB-256-4T than for devices based on SnO2 only. With these enhanced interfacial properties, P3HT:PC60BM-based iOSCs using SnO2/NDSB-256-4T (0.2 mg/mL) as an ETL showed both a higher average PCE of 3.72%, which is 33% higher than devices using SnO2 only (2.79%) and excellent device stability (over 90% of the initial PCE remained after storing 5 weeks in ambient air without encapsulation). In an extended application of the PTB7-Th:PC70BM systems, we achieved an impressive average PCE of 8.22% with SnO2/NDSB-256-4T (0.2 mg/mL) as the ETL, while devices based on SnO2 exhibited an average PCE of only 4.45%. Thus, the use of zwitterion to modify SnO2 ETL is a promising way to obtain both highly efficient and stable iOSCs.
关键词： inverted organic solar cells (iOSCs),zwitterion nondetergent sulfobetaine (NDSB-256-4T),Tin oxide (SnO2),power conversion efficiency (PCE),electron transport layer (ETL)
更新于2025-09-12 10:27:22