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Significantly enhanced electron transport of nonfullerene acceptor in blend film with high hole mobility polymer of high molecular weight: thick-film nonfullerene polymer solar cells showing high fill factor
摘要： Overcoming fill factor (FF) decay in thick fullerene active layers has been demonstrated with high hole mobility (μh) polymers. However, this issue remains as a challenge for thick active layers with nonfullerene acceptors. Here we demonstrate high FF and highly efficient nonfullerene based thick active layer with high μh polymer as the donor. Its relatively balanced hole and electron transports with a μh/μe ratio of 4.42 in 320 nm thick blend film are realized by the high molecular weight polymer induced higher electron mobility (μe approaching 1×10?3 cm2/(V s)) for the blend film. Relative to the pristine IEICO-4F nonfullerene film, 8 times increased μe for the blend film corresponds to closer interdigitation of IEICO-4F lamella and higher order face-on orientation of in-plain (200) peak of IEICO-4F molecules, which are very helpful for electron transport. As a result, solar cells with 320 nm thick binary nonfullerene active layers show outstanding FF over 70% and power conversion efficiency of 13.2%, a breakthrough for a high μh polymer as the donor. Our results suggest that high μh polymer donors are promising candidates for nonfullerene based polymer solar cells.
关键词： nonfullerene acceptor,thick-film polymer solar cells,fill factor,electron transport,high hole mobility polymer
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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Accurately Stoichiometric Regulating Oxidation States in Hole Transporting Material to Enhance the Hole Mobility of Perovskite Solar Cells
摘要： In the traditional n-i-p type perovskite solar cells (PSCs), most hole transporting materials (HTMs) rely on an uncontrolled oxidative process by using Li salt and Co (III) complex to achieve sufficient hole mobilities. Herein, we demonstrate a stabilized oxidized-phenothiazine-based HTM (OPTZ) synthesized from its neutral form (NPTZ) through a photo-redox reaction. This controllable and stable oxidation state is mainly derived from the planar structure and π-conjugation of phenothiazine core in OPTZ. The energy gap between SOMO (singly-occupied-molecular-orbital) of OPTZ and HOMO (highest-occupied-molecular-orbital) of NPTZ can suitably promote the hole hopping in hole transporting layers. Using an optimized ratio of OPTZ as dopant in NPTZ, the hole transporting mobility is effectively enhanced owing to intra- and inter-molecular charge transfer process, resulting in an enhancement in the fill factor of the PSCs. This work can provide a new strategy to obtain stabilized oxidized-HTMs, which deliver significantly enhanced hole mobilities of HTMs in PSCs.
关键词： phenothiazine,hole transport material,hole mobility,perovskite solar cell,radical cation
更新于2025-09-19 17:13:59
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Effect of Side-Chain Variation on Single-Crystalline Structures for Revealing the Structurea??Property Relationships of Organic Solar Cells
摘要： The molecular stacking assembly in the active layer plays a significant role in the photovoltaic performance of organic solar cells (OSCs). Here, we report two new small molecular donors with different side chains, FBT-O and FBT-H, and their corresponding fullerene-based OSCs. A slight change in the side chains led to a big difference in the power conversion efficiencies (PCEs). Although the molecular structures of the two donors are similar to each other, PCEs of the devices based on FBT-O were almost three times higher than those of the devices based on FBT-H, with manifold short-circuit current density, fill factor, as well as three orders of magnitude enhancement in the hole mobility. The difference in their single crystal structures was thoroughly investigated, whereby the FBT-O exhibited better planarity leading to appropriate phase separation and domain size. Furthermore, two-dimensional grazing-incidence wide-angle X-ray scattering results of the blend films revealed that the two donors retained a similar stacking structure as compared to the single-crystal structures, thus, establishing a clear relationship between the molecular stacking structure and the device performance.
关键词： side-chain modification,hole mobility,single crystal,molecular stacking structure
更新于2025-09-19 17:13:59
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Hole-transporting materials for low donor content organic solar cells: Charge transport and device performance
摘要： Low donor content solar cells are an intriguing class of photovoltaic device about which there is still considerable discussion with respect to their mode of operation. We have synthesized a series of triphenylamine-based materials for use in low donor content devices with the electron accepting [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The triphenylamine-based materials absorb light in the near UV enabling the PC71BM to be essentially the light absorbing organic semiconducting material in the solar cell. It was found that the devices did not operate as classical Schottky junctions but rather photocurrent was generated by hole transfer from the photoexcited PC71BM to the triphenylamine-based donors. We found that replacing the methoxy surface groups with methyl groups on the donor material led to a decrease in hole mobility for the neat films, which was due to the methyl substituted materials having the propensity to aggregate. The thermodynamic drive to aggregate was advantageous for the performance of the low donor content (6 wt%) films. It was found that the 6 wt% donor devices generally gave higher performance than devices containing 50 wt% of the donor.
关键词： hole mobility,low donor content,photoexcited hole transfer,Schottky junction,synthesis,photocurrent generation
更新于2025-09-16 10:30:52
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Study of p-type doping effect on P3HT: ICBA based organic photovoltaic solar cell performance
摘要： In this work, we present a simulation study for p-type doping effect on the performance of a photovoltaic organic solar cell based on P3HT: ICBA. Thus, numerical simulations are investigated on ITO/PEDOT: PSS /P3HT: PCBM/Ca/Al structure with AMPS-1D (Analysis of Microelectronic and Photonic Structures the simulation one dimension) software. Indeed, the p-type doping is considered as an original approach for the efficiency improvement of the organic solar cell. However, we noticed that this improvement is only valid for the active layer devices characterized by hole mobility μp less than 1E-3cm2V-1s-1. Furthermore, an efficiency peak of 5.856% is obtained for doping density of 1E17cm-3 corresponding to an improvement of 25.9%. Moreover, the obtained results remain in good agreement with those experimentally reported in literature.
关键词： hole mobility,efficiency,p-type doping,P3HT: ICBA,AMPS-1D,organic solar cell
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Kerala, India (12–14 June 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Measurement of hole mobility in P3HT based photovoltaic cell using space charge limited current method
摘要： Mobility of carriers is one of the pivotal parameters characterizing any semiconducting material and it is important for organic semiconductors too. The mobility of organic semiconductors remains far less when compared to inorganic counterparts and hence attempts in the direction improvise it carries tremendous significance. This paper investigates the positive charge carriers transport properties in a bulk heterojunction organic photovoltaic cell using two different Anode Buffer Layers (PEDOT:PSS and MoO3). The method of Space Charge Limited Current (SCLC) is used to compute the hole mobilities and also the values are compared. The values obtained with PEDOT:PSS and MoO3 as HTLs are 1.043x10-4 cm2 V-1S-1 and 1.357x10-4 cm2V-1S-1 respectively. It is seen that the device with higher carrier mobility exhibits better performance.
关键词： PEDOT:PSS,hole mobility,space charge limited current,MoO3,photovoltaic cell,P3HT
更新于2025-09-12 10:27:22
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Promising hole‐transporting materials for perovskite solar cells: Modulation of the electron‐deficient units in triphenylamine derivative‐based molecules
摘要： Modulation of the electron-deficient π-bridge units in 4-methoxy-N-(4-methoxyphenyl)-N-phenylbenzenamine (MeTPA)-based hole-transporting materials (HTMs) is a significant approach to improve hole mobility of HTMs for perovskite solar cells (PSCs). In this study, a class of simple MeTPA-based HTMs (H1-H4) with different π-bridged electron-deficient units were designed for the purpose of providing a theoretical model to obtain potential MeTPA-based HTMs. The results indicated that H2 to H4 exhibit better performance, such as larger Stokes shifts, smaller exciton-binding energy, better stability, good solubility, and higher hole mobility, in comparison with the parental material H1. H2 and to H4 materials with high hole mobility (5.45 × 10?4, 2.70 × 10?1, 3.99 × 10?3 cm2 V?1 second?1, respectively) may embody promising HTMs to yield good performance in PSCs. Therefore, the useful information obtained regarding control of the electron-deficient π-bridge units of MeTPA-based HTMs is an effective way to obtain excellent HTMs for PSC applications.
关键词： perovskite solar cells,condensed rings,charge transfer,hole mobility,hole-transporting materials
更新于2025-09-11 14:15:04
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Post-functionalization of polyvinylcarbazoles: An open route towards hole transporting materials for perovskite solar cells
摘要： We report on the potential of tuning poly(9-vinylcarbazole) (PVK) properties through functionalization for an application as hole transport material (HTM) for perovskite solar cells (PSCs). The synthesized PVK-based polymers were substituted with moieties of interest to improve the solubility, the charge transport properties, or to tune energy levels. Bis(4-methoxyphenyl)amine moieties were found to improve the hole mobility and to increase the HOMO level of the PVK. Therefore, PSCs employing PVK-[N(PhOCH3)2]2 as HTM exhibited a best PCE of 16.7%. Compared to spiro-OMeTAD, first studies have shown that PVK-[N(PhOCH3)2]2 could extend PSC lifetime.
关键词： Hole mobility,Hole-transporting materials,Device stability,Perovskite solar cells,Polyvinylcarbazoles
更新于2025-09-11 14:15:04
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Theoretical study of charge-transport and optical properties of indeno[1,2- <i>b</i> ]fluorene-6,12-dione-based semiconducting materials
摘要： The conducting and optical properties of a series of indeno[1,2-b]fluorene-6,12-dione (IFD)-based molecules have been systematically studied and the influences of butyl, butylthio and dibutylamino substituents on the reorganization energies, intermolecular electronic couplings and charge-injection barriers of IFD have been discussed. The quantum-chemical calculations combined with electron-transfer theory reveal that the incorporation of sulfur-linked side chains decreases reorganization energy associated with hole transfer and optimizes intermolecular π–π stacking, which results in excellent ambipolar charge-transport properties (μh = 1.15 cm2 V?1 s?1 and μe = 0.08 cm2 V?1 s?1); in comparison, addition of dibutylamino side chains increases intermolecular steric interactions and hinders perfect intermolecular π–π stacking, which results in the weak electronic couplings and finally causes the low intrinsic hole mobility (μh = 0.01 cm2 V?1 s?1). Furthermore, electronic spectra of butyl-IFD, butylthio-IFD and dibutylamino-IFD were simulated and compared with the reported experimental data. Calculations demonstrate that IFD-based molecules possess potential for developing novel infrared and near-infrared probe materials via suitable chemical modifications.
关键词： intrinsic electron mobility,structure–function relationship,indeno[1,2-b]fluorene-6,12-dione-based molecules,density functional theory (DFT),intrinsic hole mobility,electronic spectra
更新于2025-09-09 09:28:46