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Semiconducting carbon nanotubes in photovoltaic blends: The case of pTB7:PC <sub/>60</sub> BM:(6,5) SWNT
摘要： Blends of carbon nanotubes with conjugated polymer and fullerene derivatives are complex nanocomposite systems, which have recently attracted great research interest for their photovoltaic ability. Therefore, gaining a better understanding of the excitonic dynamics in such materials can be important to boost the efficiency of excitonic solar cells. Here, we studied the photophysics of a ternary system in which the polymer PTB7 and the fullerene derivative PCBM are integrated with (6,5) single walled carbon nanotubes. We highlight the contribution of SWNTs in the exciton dissociation and in the charge transfer process. These findings can be useful for the exploitation of these multi-component systems for organic photovoltaic and, in general, optoelectronic applications.
关键词： excitonic dynamics,PCBM,photovoltaic blends,PTB7,SWNTs,carbon nanotubes
更新于2025-10-22 19:40:53
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Cathode Interface Engineering Approach for a Comprehensive Study of the Indoor Performance Enhancement in Organic Photovoltaic
摘要： Organic photovoltaic (OPV) has a prospective future as a reliable energy harvesting to drive low power consumption devices for indoor applications. In this article, the outdoor (1 sun) and indoor (LED 2700K) performance of PTB7-Th:PC70BM inverted OPV with three different solution-processed electron transport layers (ETL = PFN, TiOx, and ZnO) were compared. The morphology, optical, and electrical measurements indicate the strong dependency of the OPV performance with the illumination conditions. The sample with PFN-ETL that shows the highest outdoor performance with power conversion efficiency (PCE) of 10.55% and the best-reported fill factor (FF) of 75.00% among PTB7-Th:PC70BM-based OPV, surprisingly exhibits the lowest performance when illuminated under 250–2000 lux LED 2700K. Meanwhile, the lowest outdoor performance performed by ZnO with PCE of 10.03% displays the best indoor performance with the PCE of 13.94% under 1000 lux and a PCE of up to 16.49% under 1750 lux LED lamp, respectively. The changes in the FF values can be estimated by incorporating the parasitic resistance effect due to the type ETL used. Besides, using impedance spectroscopy, we observed that indoor performance agreed well with the trend of charge collection efficiency.
关键词： impedance spectroscopy,Organic photovoltaic,electron transport layers,PTB7-Th:PC70BM,indoor performance
更新于2025-09-23 15:21:01
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Modification of Hole Transport Layers for Fabricating High Performance Nona??fullerene Polymer Solar Cells
摘要： Interfacial engineering is expected to be a feasible strategy to improve the charge transport properties of the hole transport layer (HTL), which is of crucial importance to boosting the device performance of organic solar cells (OSCs). In this study, two types of alcohol soluble materials, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) and di-tetrabutylammoniumcis–bis(isothiocyanato)bis(2,2’-bipyridyl-4,4’-dicarboxylato) ruthenium (II) (N719) dye were selected as the dopant for HTL. The doping of F4-TCNQ and N719 dye in poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) with and without integrating a graphene quantum-dots (G-QDs) layer has been explored in poly[[2,6′-4-8-di(5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thio-phenediyl:(2,2′-((2Z,2′Z)-(((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5,2-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (PTB7-Th:IEICO-4F) OSCs. The power conversion efficiency of the non-fullerene OSCs has been increased to 10.12% from 8.84%. The influence of HTL modification on the nano-morphological structures and photophysical properties is analyzed based on the comparative studies performed on the control and modified devices. The use of chemical doping and bilayer strategy optimizes the energy level alignment, nanomorphology, hole mobility, and work-function of HTL, leading to considerable reduction of the leakage current and recombination losses. Our work demonstrates that the doping of HTL and the incorporation of G-QDs layer to constitute a bilayer HTL is an promising strategy to fabricate high performance non-fullerene polymer solar cells.
关键词： UPS,PTB7-Th:IEICO-4F,atomic force microscopy,XPS,Organic solar cells
更新于2025-09-23 15:21:01
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Effects of non-halogenated solvent on the main properties of a solution-processed polymeric thin film for photovoltaic applications: a computational study
摘要： Organic photovoltaic (OPV) devices reached high solar conversion efficiencies but they are usually processed using halogenated toxic solvents. Hence, before OPV devices can be mass-produced by industrial processing, it would be desirable to replace those solvents with eco-friendly ones. Theoretical tools may be then a powerful ally in the search for those new solvents. In order to better understand the mechanisms behind the interaction between solvent and polymer, classical molecular dynamics (MD) calculations was used to produce a thin film of poly(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl (PTB7-Th), processed using two different solvents. The PTB7-Th is widely applied as a donor material in OPVs. The first solvent is the ortho-dichlorobenzene (o-DCB), which is a highly toxic solvent widely used in lab-scale studies. The second solvent is the ortho-methylanisole (o-MA), which is an eco-friendly solvent for organic photovoltaic (OPV) manufacturing. Here we use a solvent evaporation protocol to simulate the formation of the PTB7-Th film. We demonstrate that our theoretical MD calculations were able to capture some differences in macroscopic properties of thin films formed by o-DCB or o-MA evaporation. We found that the interaction of the halogenated solvent with the polymer tends to break the bonds between the lateral thiophenediyl groups and the main chain. We show that those defects may create traps that can affect the charge transport and also can be responsible for a blue shift in the absorption spectrum. Using the Monte Carlo method, we also verified the influence of the resulting MD morphology on the mobility of holes. Our theoretical results showed a good agreement with the experimental measurements and both demonstrate that o-MA can be used to make polymer thin films without any loss of key properties for the device performance. The findings here highlights the importance of theoretical results as a guide to the morphological optimization of green processed polymeric films.
关键词： Solvent evaporation,PTB7-Th,Molecular dynamics,Organic photovoltaic,Halogenated solvents,Eco-friendly solvents,Hole mobility
更新于2025-09-23 15:19:57
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Performance enhancement of conjugated polymer-small molecule-non fullerene ternary organic solar cells by tuning recombination kinetics and molecular ordering
摘要： We present our study of conjugated polymer-small molecule (SM)-non-fullerene ternary organic solar cells (OSCs), which employs conjugated polymer PTB7-Th and small molecule p-DTS(FBTTh2)2 as donors and non-fullerene molecule IEICO-4F as an acceptor. It is observed that the power conversion efficiency (PCE) of ～10.9% for PTB7-Th: p-DTS(FBTTh2)2: IEICO-4F ternary OSCs with 15 wt% of p-DTS(FBTTh2)2 SM is higher than PCE of ～9.8% for PTB7-Th: IEICO-4F OSCs. Morphological studies confirm that the addition of p-DTS(FBTTh2)2 SM in PTB7-Th: IEICO-4F binary blend improves molecular ordering and crystallinity of PTB7-Th due to the favorable interaction with p-DTS(FBTTh2)2 thereby providing 3-D textured structures consisting of a mixture of edge-on and face-on orientations. The improved molecular ordering is shown to enhance exciton generation rate, exciton dissociation, charge collection, and to reduce charge recombination, all of which boosts the PCE.
关键词： PTB7-Th,Ternary,p-DTS(FBTTh2)2,IEICO-4F,GIWAXS,Non-fullerene
更新于2025-09-23 15:19:57
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Enhanced Efficiency and Stability of Nonfullerene Ternary Polymer Solar Cells Based on Spontaneously Assembled Active Layer: The Role of a High Mobility Small Molecular Electron Acceptor
摘要： It is challenging to afford efficient and stable organic solar cells based on the as-cast active layer without any external treatments. We present a planar organic electron acceptor BPTCN with high electron mobility as a third component in nonfullerene ternary polymer solar cells, which comprises an electron-deficient 4,7-bis(5H-4,6-dioxothieno[3,4-c]pyrrol-1-yl)benzo[c][1,2,5]thiadiazole core, doubly endcapped by 2-(3-ethyl-5-methylene-4-oxothiazolidin-2-ylidene)malononitrile through the alkylated thiophene-2,5-ylene unit. It shows a π-π stacking distance of 3.60 ? and μe of 1.31 × 10?3 cm2 V?1 s?1. BPTCN exhibits an absorption maximum at 569 nm in the as-cast film and good miscibility with the NIR-absorption acceptor COi8DFIC, leading to complete f?rster energy transfer in the blends. Adding BPTCN into the PTB7-Th:COi8DFIC blend produces multiple beneficial effects: i) facilitating exciton dissociation and charge transfer at the donor/acceptor interface while suppressing bimolecular and trap-assisted recombination by analysis of the Jph–Veff, Jsc–Ilight and Voc–Ilight characteristics, ii) increasing hole and in particular electron transport; and iii) generally promoting the crystallinity of the polymer donor PTB7-Th, as revealed by grazing incidence X-ray diffraction. Moreover, the phase purity is greatly improved in the ternary blend PTB7-Th:COi8DFIC:BPTCN (1:1.05:0.45 by weight). Consequently, the tentatively optimized ternary solar cell provides a PCE of 11.62% with Voc = 0.74 V, Jsc = 25.93 mA cm-2 and FF = 60.61% in comparison with the binary systems PTB7-Th:COi8DFIC (PCE of 9.41%) and PTB7-Th:BPTCN (6.42%) in the absence of any extra treatments. After thermal aging at 80 oC for 450 h, this ternary solar cell exhibits increased stability with PCE retaining 84.39% of the initial value.
关键词： PTB7-Th,COi8DFIC,BPTCN,electron acceptor,organic solar cells,thermal stability,nonfullerene ternary polymer solar cells
更新于2025-09-23 15:19:57
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[IEEE 2020 IEEE Latin America Electron Devices Conference (LAEDC) - San Jose, Costa Rica (2020.2.25-2020.2.28)] 2020 IEEE Latin America Electron Devices Conference (LAEDC) - Impact of the Hafnium Oxide as Hole Blocking Layer on the Performance of Organic Solar Cells
摘要： The effects of hafnium oxide (HfO2) as hole blocking layer (HBL) on the stability and degradation under air environment of inverted bulk heterojunction organic solar cells (iOSC), using as donor material thieno[3,4b]thiophene-alt-benzodithiophene (PTB7) and as acceptor material [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) are presented. The ultrathin films of HfO2 layers 0.9 nm of thick were deposited by thermal evaporation. The highest power conversion efficiency obtained (PCE) was of 8.33%. The current density-voltage characteristic (J-V) was modeled through the ideal-diode equivalent circuit model. For comparison, cells with poly [(9,9-bis (30- (N,N-dimethylamino) propyl) -2,7-fluorene) -alt-2,7- (9,9-dioctylfluorene)] (PFN) and Zinc Oxide (ZnO) as hole blocking layer were fabricated. The three groups of cells were exposed to air for 1000 h. The electrical parameters extracted from the current density–voltage characteristic (J–V) were analyzed. The PCE for cells manufactured with HfO2 as HBL remains around 30% after 1000 h under air environment, showing less degradation than iOSCs with ZnO.
关键词： electron transport layer,HfO2,PFN,PTB7:PC70BM solar cells,hafnium oxide,organic solar cells,ZnO,Degradation,OSC stability
更新于2025-09-23 15:19:57
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Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC <sub/>71</sub> BM-based organic photovoltaic cells
摘要： Herein, we report the synthesis of nontoxic pyrite iron sulfide (FeS2) nanocrystals (NCs) using a two-pot method. Moreover, we study the influence of these NCs incorporated into the PTB7:PC71BM active layer of bulk-heterojunction ternary organic photovoltaic (OPV) cells. The OPV devices are fabricated with the direct configuration glass/ITO/PEDOT:PSS/PTB7:PC71BM:FeS2/PFN/FM. The Field’s metal (FM) is a eutectic alloy composed of 32.5% Bi, 51% In and 16.5% Sn by weight that melts at 62 °C. It is deposited on the active layer/PFN under atmospheric conditions. Ternary active layers are prepared by adding small amounts of the semiconducting FeS2 NCs at different weight ratios of 0.0, 0.25, 0.5, and 1.0 wt % with respect to the electron donor PTB7. With respect to the reference device (without FeS2), a 21% increase in the power conversion efficiency (PCE) is observed for OPVs with 0.5 wt % FeS2, such that the PCE of the OPVs is enhanced from 5.69 to 6.47%. According to the Kruskal–Wallis and Mann–Whitney statistical tests, all OPV devices follow the same trend.
关键词： iron disulfide,nanoparticles,pyrite,organic photovoltaic cells (OPVs),PTB7
更新于2025-09-16 10:30:52
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Design of parallel-connected polymer tandem solar cells using efficient low bandgap PTB7-Th:PC71BM blend
摘要： Parallel-connected tandem cells adopting a highly efficient donor polymer, PTB7-Th, combined with acceptor fullerene PC71BM as the back sub-cell was introduced to further improve the performance of polymer solar cells. Design of the device architecture was investigated using modeling and simulation methods based on the transfer matrix formalism. To optimize the device structure, detailed analysis of the effect of active layer thickness, different device structure, and transparent Ag intermediated electrode on the short-circuit current density has been studied. It was found the long-wavelength absorption in the top-illuminated ITO-free back cell was significantly enhanced due to the resonant microcavity effect, leading to an efficient utilization of the incident light and increased photocurrent. Giving these advantages, the power conversion efficiency of the parallel homo-tandem cell was estimated to be ~ 11%, which was ~ 15% higher than that of a single cell of PTB7-Th. Moreover, the maximum achievable current density and the corresponding optimum active layer thickness of the sub-cells varied a little as the thickness of ultrathin Ag layer was changed, indicating that parallel connection architecture provided more freedom in the design and optimization for high-performance tandem solar cells.
关键词： PC71BM,Polymer solar cells,Microcavity effect,Transfer matrix formalism,PTB7-Th,Parallel-connected tandem cells
更新于2025-09-12 10:27:22
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Functionalized and reduced graphene oxide as hole transport layer and for use in ternary organic solar cell
摘要： Here is reported the performance of organic solar cells (OSCs) by using a new graphene oxide derivative as hole transport layer (HTL). OSCs are based on the PTB7:PC71BM blend as active layer and the alternative top electrode Field’s metal (Bi/In/Sn: 32.5%, 51%, 16.5%), which can be easily deposited through a vacuum-free process at regular atmosphere and low temperature (90°C). Graphene oxide (GO) was chemically functionalized and reduced with pentafluorophenylhydrazine, this fluorinated reduced graphene oxide (F5-rGO) was suspended in dimethylformamide for easy deposit by wet techniques such as spin-cast. F5-rGO has a work-function of 5.1 eV due to the high electronegativity of fluorine atoms incorporated into the GO sheets. The best achieved PCE of the OSCs fabricated for a single layer of F5-rGO was 5.82%. An enhanced PCE of 7.67% when F5-GO was used as interlayer between ITO and PEDOT:PSS was reached (PCE of PEDOT:PSS-based was 7.29%). Additionally, functionalized and reduced (chemically) graphene oxide (H5-rGO) was also obtained from GO treated with phenylhydrazine, and ternary OSCs were also prepared by adding H5-rGO to the PTB7:PC71BM blend at different weight ratios: 0, 3, and 6%. The best results were achieved with 3% of H5-rGO: OSCs presented a PCE of 7.56%.
关键词： Functionalized-reduced graphene oxide,PTB7:PC71BM,Hole transport layer,Ternary OSCs,Organic solar cells
更新于2025-09-11 14:15:04