Poly(3-hexylthiophene-2,5-diyl Research Articles

Evaluation of Industrial Poly(tert-butyl acrylate) insulated A p-channel Organic Field-Effect Transistor (PtBA-p-OFET)

Poly(tert-butyl acrylate) (PTB-p-A) has been investigated as a promising insulator layer for p-channel organic field effect transistors (p-OFETs) using the p-type semiconductor Poly(3-hexylthiophene-2,5-diyl (P3HT) due to its favorable insulating properties, good film-forming ability and electrical charge separation properties. Top-gate, bottom-contact PTBA-p-OFET devices are fabricated with Indium Thin Oxide (ITO) source/drain electrodes and a P3HT organic semiconductor layer. The frequency-dependent capacitance of the PTBA-p-OFETs was studied through a plot to determine the key parameters, including the threshold voltage (VTh), field-effect mobility (μFET), and the current on/off ratio (Ion/off) of the device. The PTB-p- OFETs exhibit field-effect mobility value of 6.13x10-4 (cm2/V.s), an on/off current ratio of 1.11x102, and a threshold voltage of -15.8 V. The capacitance-frequency characteristics of the capacitor structure were analyzed and found to have as 7.6 nF/cm2 per unit area. This work presents PTBA as a promising for high-performance p-OFET applications.

Introduction of graphene oxide nanosheets in self-oriented air-stable poly(3-hexylthiophene-2,5-diyl) to enhance the ammonia gas sensing of a p-channel thin film transistor

A self-assembled highly oriented P3HT (Poly(3-hexylthiophene-2,5-diyl))/GO (Graphene oxide) nanocomposite-based p-channel organic field-effect transistor (OFET) for real-time ammonia sensing has been fabricated and characterized on a p++ (highly boron-doped) silicon substrate at room temperature (∼25 °C). A low-cost facile floating film transfer method has been adopted to fabricate the sensing channel of OFET with optimized and uniform thickness (∼25 nm). The electrical characterizations and NH3 sensing performance of the P3HT/GO nanocomposite OFET with palladium electrode have been characterized and compared with pristine P3HT-based OFET. It is demonstrated that the polymer nanocomposite-based OFET with Pd electrode has a relatively high response of ∼63% at 80 ppm NH3 gas. A reduction of 60.41% in field-effect mobility (0.0551 cm2/ V. sec. to 0.02181 cm2/V. sec.) and a 29.4% change in threshold voltage (−4.758 V to −6.157 V) has been observed by varying the NH3 gas concentration over 0–80 ppm. It has an improved response time of ∼44 s and recovery time of ∼82 s due to improved crystallinity and grain size of the sensing layer. All the electrical characterizations and sensing measurements have been done at RT and 55% relative humidity.

Evolutionary optimization of the short-circuit current enhancement in organic solar cells by nanostructured electrodes

Using a particle swarm optimization algorithm (a population-based stochastic optimization technique) combined with 3D finite-difference time-domain simulations, we inverse design periodic arrays of metallic nanoparticles on indium-tin-oxide electrodes and nanoholes in metallic thin films working as electrodes in P3HT (Poly(3-hexylthiophene-2,5-diyl)):PCBM ([6,6]-Phenyl C61 butyric acid methyl ester) organic solar cells to achieve the maximum short-circuit currents (Jsc). Nanohole-array electrodes have large optical losses, leading to a net reduction of Jsc compared to a reference solar cell. On the other hand, nanoparticle arrays can lead to a significant enhancement of Jsc of up to 20%. Detailed simulations show that this enhancement is caused by the grating coupling of the incident light to surface plasmon polaritons at the interface of the metal electrode and the hole transport layer, leading to the enhancement of the electromagnetic field in the organic blend.

Comparative Photovoltaics of P3HT:N2200 and P3HT: Small-Gap Fullerene Ethyl-Nipecotate Bulk Heterojunction Structures

This work deals with the study on the optical absorption and photoluminescence spectra of a p-type organic semiconducting polymer, regioregular poly 3-hexylthiophene-2,5-diyl (P3HT) and the absorption spectra of an n-type fullerene-based small-gap fullerene-ethyl nipecotate (Fullerene-EN) and a non-fullerene-based polynaphthalene bithiophene (N2200) semiconducting materials. The band gap of P3HT, N2200, and small-gap fullerene-ethyl nipecotate are 2.42, 1.65, and 1.51 eV, respectively, calculated from experimental results through the Tauc equation. Active layers with blends of P3HT and small-gap fullerene-ethyl nipecotate and P3HT and N2200 have been used to fabricate bulk heterojunction (BHJ) structures. The P3HT:N2200 BHJ structure follows the current density versus voltage characteristics of a photovoltaic device with 0.28% power conversion efficiency, 1.58 mA/cm2 short-circuit current density, and 41% fill factor. However, the P3HT:small-gap fullerene-ethyl nipecotate structure does not show any photovoltaic J–V characteristics.

Efficiency improvement for perovskite-inspired Cs3Sb2I9 solar cells using P3HT as the hole transport material

In this work, we introduce P3HT (poly(3-hexylthiophene-2,5-diyl)) as an efficient hole transport material (HTM) for lead-free Cs3Sb2I9 perovskite-inspired solar cells.

Investigation of a Perovskite Solar Cell and Various Parameters Impact on Its Layers and the Effect of Interface Modification by Using P3HT as an Ultrathin Polymeric Layer Through SCAPS-1D Simulation

Recently, renewable energy sources such as solar energy have gained much attention for electricity generation because of their easy access and infinite resources. Solar cells are a good choice for this goal. Among the various solar cells that have already been studied, perovskite solar cells (PSCs) have recently is interested in researchers due to their tremendous improvement in system performance and efficiency. This type of solar cell is divided into several layers, each of which has its role in the structure of the cell. Front Contact/Electron transporting material/Absorbent (perovskite)/Hole transporting layer/Back Contact. The overall structure of these cells has shown a maximum efficiency of about 22% which is good efficiency for solar cells. However, this type of solar cell suffers from stability problems, especially at the junction point between the HTM and the perovskite (absorber) layer, despite its cost-effectiveness advantages. To solve this problem, recent studies have been transferred to a study called interface engineering. In this study, the mentioned interfaces are modified by some materials that have regular and stable structures such as polymers. Many polymeric modifiers have been studied in recent years. Among them, P3HT (Poly(3-hexylthiophene-2,5-diyl)) has provided the best results. In this paper, first, the effect of different layer properties such as their thickness and charge carrier density were investigated and optimal parameters were obtained for each one using SCAPS-1D (Solar Cell Capacitance Simulator) software. Then we simulated the structure of a perovskite solar cell using a polymeric modifier in its structure. The results showed that by adding an ultrathin polymeric film as an interface between HTM and perovskite, the performance of the device was improved and its efficiency was enhanced. The final efficiency of the device with the optimal parameters was obtained about 26.5%.

The role of solvent additive in metal nano-composite doped thin film organic solar cell

In this study, organic solar cells (OSCs) were designed using the solution processing method based on spin coating. The influence of solvent additive (1-chloronapthalene (CN)) and cadmium doped barium nitrate nanoparticle incorporated into the photoactive medium based on poly(3-hexylthiophene-2,5-diyl (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was investigated. The power conversion efficiency of the pristine device was compared to the power conversion efficiency of the devices fabricated with 30v% of 1- chloronapthalene and different weight concentrations of nanoparticles. An optimum efficiency of 3.55 % was attained at 0.3 wt.% with solvent additive compared to 3.25 % obtained for the pristine device. This increase is attributed to a rise in charge transport of 5.32 × 10−2 cm2V−1s−1. Further investigation on the morphological properties of the nanoparticles reveals the crystalline nature of the nanoparticle.

Synthesis and Photovoltaics of Novel 2,3,4,5-Tetrathienylthiophene-co-poly(3-hexylthiophene-2,5-diyl) Donor Polymer for Organic Solar Cell.

This report focuses on the synthesis of novel 2,3,4,5-tetrathienylthiophene-co-poly(3-hexylthiophene-2,5-diyl) (TTT-co-P3HT) as a donor material for organic solar cells (OSCs). The properties of the synthesized TTT-co-P3HT were compared with those of poly(3-hexylthiophene-2,5-diyl (P3HT). The structure of TTT-co-P3HT was studied using nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FTIR). It was seen that TTT-co-P3HT possessed a broader electrochemical and optical band-gap as compared to P3HT. Cyclic voltammetry (CV) was used to determine lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy gaps of TTT-co-P3HT and P3HT were found to be 2.19 and 1.97 eV, respectively. Photoluminescence revealed that TTT-co-P3HT:PC71BM have insufficient electron/hole separation and charge transfer when compared to P3HT:PC71BM. All devices were fabricated outside a glovebox. Power conversion efficiency (PCE) of 1.15% was obtained for P3HT:PC71BM device and 0.14% was obtained for TTT-co-P3HT:PC71BM device. Further studies were done on fabricated OSCs during this work using electrochemical methods. The studies revealed that the presence of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on the surface of indium tin oxide (ITO) causes a reduction in cyclic voltammogram oxidation/reduction peak current and increases the charge transfer resistance in comparison with a bare ITO. We also examined the ITO/PEDOT:PSS electrode coated with TTT-co-P3HT:PC71BM, TTT-co-P3HT:PC71BM/ZnO, P3HT:PC71BM and P3HT:PC71BM/ZnO. The study revealed that PEDOT:PSS does not completely block electrons from active layer to reach the ITO electrode.

Emerging Photovoltaic (PV) Materials for a Low Carbon Economy

Emerging photovoltaic (PV) technologies have a potential to address the shortcomings of today’s energy market which heavily depends on the use of fossil fuels for electricity generation. We created inventories that offer insights into the environmental impacts and cost of all the materials used in emerging PV technologies, including perovskites, polymers, Cu2ZnSnS4 (CZTS), carbon nanotubes (CNT), and quantum dots. The results show that the CO2 emissions associated with the absorber layers are much less than the CO2 emissions associated with the contact and charge selective layers. The CdS (charge selective layer) and ITO (contact layer) have the highest environmental impacts compared to Al2O3, CuI, CuSCN, MoO3, NiO, poly (3-hexylthiophene-2,5-diyl (P3HT)), phenyl-C61-butyric acid methyl ester (PCBM), poly polystyrene sulfonate (PEDOT:PSS), SnO2, spiro-OMeTAD, and TiO2 (charge selective layers) and Al, Ag, Cu, FTO, Mo, ZnO:In, and ZnO/ZnO:Al (contact layers). The cost assessments show that the organic materials, such as polymer absorbers, CNT, P3HT and spiro-OMeTAD, are the most expensive materials. Inorganic materials would be more preferable to lower the cost of solar cells. All the remaining materials have a potential to be used in the commercial PV market. Finally, we analyzed the cost of PV materials based on their material intensity and CO2 emissions, and concluded that the perovskite absorber will be the most eco-efficient material that has the lowest cost and CO2 emissions.

Synthesis and photophysical characterization of isoindigo building blocks as molecular acceptors for organic photovoltaics

Five isoindigo-based donor-acceptor-donor (D-A-D) type small molecules have been synthesized in order to investigate their intramolecular charge transfer characteristics. UV–vis absorption of these dyes exhibits a wide absorption band ranging from 300 to 650 nm with two distinct bands, giving the narrow bandgaps between 1.72 and 1.85 eV. Taking into account their HOMO-LUMO energy levels and bandgaps, isoindigo dyes have been used in the active layer of organic solar cell (OSC) devices. When these small molecule semiconductors were used as acceptors with the donor poly(3-hexylthiophene-2,5-diyl (P3HT) polymer in the inverted OSC devices, the highest power conversion efficiency (PCE) was obtained as 0.10% for pyrene-substituted isoindigo derivative.

Significantly improved efficiency of organic solar cells incorporating Co3O4 NPs in the active layer

Effect of various concentrations of fabricated cobalt oxide (Co3O4) nanoparticles (NPs) in the active layer of different donors and acceptors based hybrid organic bulk heterojunction-BHJ devices were investigated using inverted architecture. The organic active layer comprising different donors P3HT (poly(3-hexylthiophene-2,5-diyl) and PTB7 (Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b] thiophenediyl]][6,6]) and acceptor (phenyl-C-butyric acid methyl ester (PC60BM and PC70BM) materials. The incorporation of NPs in the binary blends of P3HT:PC60BM and PTB7:PC70BM enhanced the power conversion efficiency (PCE) of resulting ternary devices. This increase in PCE is mostly due to decrease in series resistance (Rs) with an optimum amount of Co3O4 in the organic photoactive layer. It was found that the ternary blend has higher absorbance relative to a binary blend of P3HT:PCBM. Addition of NPs in the active materials blend increased film roughness and form interpenetrating network to facilitate charges transportation in the active layer. The higher amount of NPs enhanced agglomerations which caused to break down the BHJ led to decrease the performance of the ternary devices.

Atomic-scale understanding of dichlorobenzene-assisted poly 3-hexylthiophene-2,5-diyl nanowire formation mechanism

Low-dimensional Poly 3-hexylthiophene-2,5-diyl (P3HT) structures that serve efficient exciton dissociation in organic solar cells, play a major role in increasing the charge collection, and hence, the efficiency of organic devices. In this study, we theoretically and experimentally investigate the Dichlorobenzene (DCB)-assisted formation of P3HT nanowires. Our experiments show that the solution of DCB molecules drive randomly oriented P3HT polymers to form well-stacked nanowires by stabilizing tail-tail and π−π interactions. Here the question is how DCB molecules migrate into the P3HT layers while forming the nanowire structure. Our density functional theory-based calculations reveal that the vertical migration of the DCB molecules between P3HT layers is forbidden due to a high energy barrier that stems from strong alkyl chain-DCB interaction. In contrast to vertical diffusion, lateral diffusion of DCB molecules in between P3HT layers is much more likely. Our results show that migration of a DCB molecule occurs through the alkyl groups with a low energy barrier. Therefore, laterally diffused DCB molecules assist nucleation of top-to-top stacking of P3HT polymers and formation of well-ordered nanowires.

Spin dynamics of light-induced charge separation in composites of semiconducting polymers and PC60BM revealed using Q-band pulse EPR.

Light-induced processes in composites of semiconducting polymers and fullerene derivatives have been widely studied due to their usage as active layers of organic solar cells. However the process of charge separation under light illumination - the key process of an organic solar cell is not well understood yet. Here we report a Q-band pulse electron paramagnetic resonance study of composites of the fullerene derivative PC60BM ([6,6]-phenyl-C61-butyric acid methyl ester) with different p-type semiconducting polymers regioregular and regiorandom P3HT (poly(3-hexylthiophene-2,5-diyl), MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]), PCDTBT (poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]), PTB7 (poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}))), resulting in a detailed description of the in-phase laser flash-induced electron spin echo (ESE) signal. We found that in organic donor-acceptor composites the laser flash simultaneously induces species of two types: a polymer˙+/fullerene˙- spin-correlated polaron pair (SCPP) with an initial singlet spin state and (nearly) free polymer˙+ and fullerene˙- species with non-equilibrium spin polarization. Species of the first type (SCPP) are well-known for polymer/fullerene blends and are usually associated with a charge-separated state. Also, spin polarization of long-living free species (polarons in deep traps) is affected by the laser flash, which is the third contribution to the flash-induced ESE signal. A protocol for extracting the in-phase ESE signal of the SCPP based on the dependence of the microwave nutation frequency on the strength of the spin coupling within the polaron pair was developed. Nutation experiments revealed an unusual pattern of the SCPP in RR-P3HT/PC60BM composites, from which the strength of the exchange interaction between the polymer˙+ and fullerene˙- was extracted. In composites with low-efficient polymers the contribution of the SCPP to the in-phase ESE signal is high, while in composites with high-efficient polymers it is low. This finding can be used as a selection criterion of charge separation efficiency in the polymer/fullerene composites.

Morphology of organic semi-crystalline polymer after thermal nanoimprint

The morphology of highly regular, semi-crystalline P3HT (poly 3-hexylthiophene-2.5-diyl) after thermal nanoimprint is studied and compared to that of its amorphous counterpart. Differential scanning calorimetry measurements of both materials provide the glass transition temperature (below room temperature) as well as the melting temperature (Tm ≈ 235 °C) and the crystallization temperature (Tc ≈ 200 °C) of the semi-crystalline polymer. Imprint experiments are performed at temperatures below and above the melting temperature of the crystallites. The samples imprinted with line structures in the range of 135–500 nm are investigated by scanning electron microscopy and transmission measurements. In agreement with Tm, the investigations indicate that the crystallites do not melt when semi-crystalline P3HT is imprinted below Tm. After imprint above Tm, no more indication of the crystallites is found. Furthermore, physical self-assembly only occurred after imprint beyond Tm with semi-crystalline P3HT, indicating a fully amorphous state. The morphology observed—the roughness of the surface within partly filled cavities when crystallites are present—correlates well with the results from optical measurements.

Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi‐Orthogonal Solvent Blends

Design rules are presented for significantly expanding sequential processing (SqP) into previously inaccessible polymer:fullerene systems by tailoring binary solvent blends for fullerene deposition. Starting with a base solvent that has high fullerene solubility, 2‐chlorophenol (2‐CP), ellipsometry‐based swelling experiments are used to investigate different co‐solvents for the fullerene‐casting solution. By tuning the Flory‐Huggins χ parameter of the 2‐CP/co‐solvent blend, it is possible to optimally swell the polymer of interest for fullerene interdiffusion without dissolution of the polymer underlayer. In this way solar cell power conversion efficiencies are obtained for the PTB7 (poly[(4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)(3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl)]) and PC61BM (phenyl‐C61‐butyric acid methyl ester) materials combination that match those of blend‐cast films. Both semicrystalline (e.g., P3HT (poly(3‐hexylthiophene‐2,5‐diyl)) and entirely amorphous (e.g., PSDTTT (poly[(4,8‐di(2‐butyloxy)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)‐alt‐(2,5‐bis(4,4′‐bis(2‐octyl)dithieno[3,2‐b:2′3′‐d]silole‐2,6‐diyl)thiazolo[5,4‐d]thiazole)]) conjugated polymers can be processed into highly efficient photovoltaic devices using the solvent‐blend SqP design rules. Grazing‐incidence wide‐angle x‐ray diffraction experiments confirm that proper choice of the fullerene casting co‐solvent yields well‐ordered interdispersed bulk heterojunction (BHJ) morphologies without the need for subsequent thermal annealing or the use of trace solvent additives (e.g., diiodooctane). The results open SqP to polymer/fullerene systems that are currently incompatible with traditional methods of device fabrication, and make BHJ morphology control a more tractable problem.

Enhanced efficiency of bilayer polymer solar cells by the solvent treatment method

We successfully facilitated an enhancement in the efficiency of polymer bilayer solar cells using the solvent treatment method. Specifically, after creating a poly(3-hexylthiophene-2,5-diyl(P3HT)/[6,6]-phenyl-C61-butyric-acid-methyl-ester (PCBM) bilayer structure by the use of an orthogonal solvent, we applied the solvent treatment method to the bilayer solar cell to improve the device performance. When the interfaces between the P3HT layer and the PCBM layer and between the PCBM layer and the Al electrode were treated with methanol, the bilayer SCs showed significantly enhanced device performance with improved Jsc FF, and PCE.

First step into space: performance and morphological evolution of P3HT:PCBM bulk heterojunction solar cells [corrected] under AM0 illumination.

P3HT (poly(3-hexylthiophene-2,5-diyl)):PC61BM ([6,6]-phenyl-C61 butyric acid methyl ester) bulk heterojunction solar cells are fabricated and characterized as a function of solar intensity, temperature, and aging at vacuum conditions under illumination with AM0 illumination for testing potential use in space applications. The evolution of the inner film morphology is probed with grazing incidence X-ray scattering techniques and correlated with the evolution of the efficiency during aging. Grazing incidence wide-angle X-ray scattering shows almost no change of the crystalline structure of the P3HT:PCBM films due to aging. In contrast, the morphological evolution on the mesoscale extracted from grazing incidence small-angle X-ray scattering can explain the observed decay of the overall efficiency. The behavior at high solar intensities as well as elevated temperatures suggests that organic solar cells have high potential for space applications in the future.

Enhanced performance of polymer:fullerene bulk heterojunction solar cells upon graphene addition

Graphene has potential for applications in solar cells. We show that the short circuit current density of P3HT (Poly(3-hexylthiophene-2,5-diyl):PCBM((6,6)-Phenyl C61 butyric acid methyl ester) solar cells is enhanced by 10% upon the addition of graphene, with a 15% increase in the photon to electric conversion efficiency. We discuss the performance enhancement by studying the crystallization of P3HT, as well as the electrical transport properties. We show that graphene improves the balance between electron and hole mobilities with respect to a standard P3HT:PCBM solar cell.

Mapping polarons in polymer FETs by charge modulation microscopy in the mid-infrared

We implemented spatial mapping of charge carrier density in the channel of a conventional polymer Field-Effect Transistor (FET) by mid-infrared Charge Modulation Spectroscopy (CMS). CMS spectra are recorded with a high sensitivity confocal Fourier Transform Infra-Red (FTIR) microscope by probing electroinduced Infra-Red Active Vibrational (IRAV) modes and low-energy polaron bands in the spectral region 680–4000 cm−1. Thanks to the high specificity and strong oscillator strength of these modes, charge-induced reflectance measurements allow quantitative estimation of charge carrier densities within the FET channel, without the need for amplitude or phase modulation. This is illustrated by identifying the contribution of intrinsic and electrostatically induced polarons to conduction, and by mapping the polaron spatial distribution in a P3HT (Poly(3-hexylthiophene-2,5-diyl)) FET channel under different drain-source bias conditions. This work demonstrates the potential of mid-infrared charge modulation microscopy to characterize carrier injection and transport in semiconducting polymer materials.

Crystallization-Induced 10-nm Structure Formation in P3HT/PCBM Blends

The miscibility and aggregation of PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) in a polymer matrix is of great importance for the development of fullerene-based organic photovoltaic cells (OPVs). In this study we have systematically investigated the loading of PCBM in regioregular and regiorandom P3HT (poly(3-hexylthiophene-2,5-diyl). Using optical microscopy, we demonstrate the partial miscibility of PCBM in thermally annealed P3HT films and relate it to the relative crystallinity of P3HT. The low polydispersity and the nearly 100% regioregularity of a self-synthesized P3HT allowed a detailed X-ray characterization as a function of PCBM content, revealing a superstructure of periodic amorphous and crystalline lamellar domains of fully chain extended polymer chains. PCBM dissolves in the amorphous interlamellar P3HT regions (partially index-matching the X-ray scattering contrast) up to a threshold, above which PCBM aggregates start to form. These results show that crystallization of P3HT into 10-nm-...