Blend Of P3HT Research Articles

Characterization and modeling of TIPS-pentacene-poly(3-hexyl) thiophene blend organic thin film transistor

Thin film transistor based on the blend of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) and the poly(3-hexylthiophene) (P3HT) was made on SiO2 insulator layers by spin coating method. The blend of TIPS-pentacene and P3HT was prepared for molar ratio of TIPS:P3HT=1:0.4ml. Electrical characteristics of the blend of TIPS-pentacene and P3HT transistors under dark and white light illuminations were analyzed. We have exploited the experimental curves current–voltage of our TFT to extract electrical parameters such us mobility, threshold voltage, sub-threshold voltage and trapped density under dark and white light illumination. Finally we have studied the effect of white light illumination on threshold voltage of the organic thin film transistor based on the blend of TIPS-pentacene and P3HT.

Improve Efficiency of Organic Solar Cell by Adding Dispersed ZnO Nanoparticles

The poly (3-hexylthiophene) (P3HT) is a promising candidate material for using in polymer solar cells researches due to its good absorbance and stability. In this study, we present the electro-optical performance of organic polymer solar cells based on P3HT: [6,-phenyl-C61-butyric acid methyl ester (PCBM) with weight ratio of 1:1. We added ZnO nanoparticles into the blending of P3HT and PCBM to improve the performance of polymer solar cells. ZnO nanoparticles are very promising inorganic metal oxides for use in organic solar cells because of its low cost, nontoxicity, high reflectance and good electron transport properties. The morphology of polymer solar cell was improved due to the additional of ZnO nanoparticles. The effects of thermal annealing on the solar cell had been studied. The post-annealing shows significant improvement in the performance for solar cell. How to prevent ZnO nanoparticles to agglomerate is essential as they are added to the active layer of the solar cell. Well dispersed ZnO nanoparticles are obtained by using the methanol solvent. The best performances of the solar cell with short-circuit current density of 14.66 mW/cm2 and efficiency of 3.92% can be obtained after post-annealed with well being dispersed 1.3wt% ZnO nanoparticles in the active layer.

A study of donor/acceptor interfaces in a blend of P3HT/PCBM solar cell: Effects of annealing and PCBM loading on optical and electrical properties

Optical, structural and electrical properties based on blend of P3HT: PCBM thin films have been investigated for several PCBM loading whilst exposed to air. Experimental evidence indicates that the peak absorption for PCBM with highest loading concentration show greater reduction in intensity upon annealing temperature of 175°C. This provides useful information regarding PCBM segregation associated with annealing process. Comparison of GIXRD patterns indicates an increase in intraplanar d spacing and polymer grain size upon thermal annealing. Variation in open circuit voltage and short circuit current with annealing temperatures, suggests that the latter remains almost constant up to around 100°C and improves gradually with temperature thereafter, whilst the former improves with temperature and the onset of deterioration in current density is linked to percentage PCBM loading. These results are further explained or supported by optical absorption spectroscopy to account for PCBM clustering. A power conversion efficiency of 3.38% was achieved at 175°C for devices fabricated and tested in air.

Bulk heterojunction photodiode: To detect the whole visible spectrum

In this paper, we report an organic bulk heterojunction photo-sensor that has been fabricated by using a composite of a polymer material poly(3-hexylthiophene-2,5-diyl) (P3HT) and a dye material vanadyl-phthalocyanine (VOPcPhO). The UV–Vis spectrum shows that this composite exhibits a broad absorption over the whole visible range. The photoluminescence (PL) spectra of P3HT and VOPcPhO blend have been studied to optimize the ratio of P3HT and VOPcPhO. The photo-sensitivity has been investigated under different applied voltages in reverse direction. The photoconductivity sensitivity value has been calculated as 5.65×102Sm/W. The photo-responsivity of the sensor has been investigated under 100mW/cm2 illumination. It is found that the sensor exhibits a rapid change in the photocurrent by the switching of the light between ON and OFF states and shows stable plateau values. Since this new photo-sensor device can harvest photons over the whole visible range and is inexpensive to manufacture, therefore, it has a great potential for practical applications.

Understanding the phase separation evolution in efficient P3HT : IC70BA-based bulk-heterojunction polymer solar cells

The effects of solvent and thermal annealing on the morphology of the active layers and the photovoltaic performance of bulk-heterojunction (BHJ) polymer solar cells (PSCs) are investigated systematically, for PSCs based on a blend of poly(3-hexylthiophene) (P3HT) as a donor and indene-C70 bisadduct (IC70BA) as an acceptor. IC70BA crystallites are found reasonably well dispersed in the P3HT matrix after spin-coating. However, the IC70BA crystallites coarsen in size after annealing, which are clearly evidenced by transmission electron microscopy. Simultaneously, space charge limited current measurements demonstrate that solvent and thermal annealing can improve the hole and electron mobility, which reduces charge-carrier recombination and improves charge-carrier transport in the P3HT and IC70BA blend layers. The corresponding current–voltage curves are measured in quantity and we propose a model to show the variation of the ordered structure of P3HT domains and IC70BA crystallite characteristics in the phase separation process, expressing a viewpoint on the high performance of BHJ PSCs.

Exciton and Hole-Transfer Dynamics in Polymer: Fullerene Blends

Ultrafast hole transfer dynamics from fullerene derivative to polymer in bulk heterojunction blends are studied with visible-pump - IR-probe spectroscopy. The hole transfer process is found to occur in 50/300 fs next to the interface, while a longer 15-ps time is attributed to exciton diffusion towards interface in PC71 BM domains. High polaron generation efficiency in P3HT blends indicates excellent intercalation between the polymer and the fullerene even at highest PC71 BM concentration thereby yielding a valuable information on the blend morphology.

Study of the microstructure of inkjet-printed P3HT:PCBM blend for photovoltaic applications

Recently, great interest has been devoted to cost-effective alternative energy sources such as organic solar cells because of the mechanical flexibility and the versatility of chemical structure, the low cost of fabrication, and ease of processing. As regards this last point, the possibility to deposit organic materials from solutions at low temperatures makes them employable for fabricating printed solar cells by direct printing methods. In this study, we used the inkjet-printing technology to deposit P3HT blends with various fullerene acceptors ([60]PCBM, [70]PCBM and bis[60]PCBM) dissolved in single solvents, 1,2-dichlorobenzene (DCB) and chlorobenzene (CB), and their mixtures. After optimizing the printing parameters (printhead speed, drop emission frequency, and substrate temperature), the effect of the solvents on the morphology of the photoactive layers was analyzed through Raman spectroscopy and atomic force microscopy. Polymer solar cells with the structure glass/ITO/PEDOT:PSS/blend/Ca/Al were fabricated and characterized by current–voltage (I–V) measurements under 100 mW/cm2 AM 1.5G illumination. A comparative study of the performances of the devices was performed based on three different fullerene derivatives, correlating them to the microstructure of the printed blend films. The optimal devices were obtained when the blend films were deposited from a mixture of DCB:CB 4:1 by volume: this was in agreement with the most favorable morphology of these films.

Comparative study of spectral and morphological properties of blends of P3HT with PCBM and ICBA

We report a comparative study on spectral and morphological properties of two blend systems for polymer solar cells: the donor material poly(3-hexylthiophene) (P3HT) in combination with the acceptor material of either [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) or indene-C60 bisadduct (ICBA) that was reported to enhance efficiencies of polymer solar cells. Optical microscopy and grazing incidence X-ray scattering reveal the stronger tendency of PCBM to from larger and more ordered domains/grains than ICBA either in pure or blend films. Compared to PCBM, the presence of ICBA also substantially perturbs the organization and longer-range ordering of P3HT in increasing the ICBA ratio in blends. With larger and more ordered phase-separated domains, the P3HT/PCBM blend films exhibit significant optical scattering at higher PCBM ratios. Yet, such optical scattering is not significant for P3HT/ICBA blends (even with high ICBA ratios). Overall, results here suggest the reported higher efficiencies of P3HT/ICBA solar cells (vs. P3HT/PCBM cells) cannot be attributed to larger and/or more ordered phase-separated donor–acceptor domains and other characteristics play more important roles in this case.

Beyond PCBM: Understanding the Photovoltaic Performance of Blends of Indene‐C60 Multiadducts with Poly(3‐hexylthiophene)

AbstractThe effect of functionalization of the C60 cage with multiple indene groups in relation to the dynamics of photogenerated species in blends with poly(3‐hexylthiophene) (P3HT) and the performance of P3HT:indene‐C60 photovoltaic devices is reported. Despite the systematic decrease of the electron affinity of the acceptor with the number of additions, exciton dissociation is efficient in blends of P3HT with all three indene‐C60 derivatives. By replacing the prototypical acceptor [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) with mono‐indene‐C60 (ICMA) or a sample of a mixture of bis‐indene‐C60 regioisomers (ICBA) the power conversion efficiency is enhanced, predominantly due to an increase in the open‐circuit voltage that originates from the lower electron affinity of the indene‐C60 acceptor. The use of an acceptor sample that represents a mixture of tris‐indene‐C60 (ICTA) regioisomers results in a reduction of the short‐circuit current density, fill factor, and open‐circuit voltage of the photovoltaic device. The electron mobility in ICTA domains is ca. a factor 10 lower than in ICMA and ICBA. Density functional theory calculations of the LUMO energies in ICTA isomers demonstrate that energetic disorder caused by the presence of regioisomers is unlikely to be responsible for the low electron mobility in ICTA. The observed deterioration in device performance is attributed to the formation of small ICTA clusters “coated” in insulating indene units that reduce electronic coupling between the molecules and cause the low electron mobility in ICTA domains. These findings indicate that while multiple additions to a fullerene cage provide a facile methodology for controlling the energy levels, they may have limited success in improving OPV device performance.

Mechanism of Mobile Charge Carrier Generation in Blends of Conjugated Polymers and Fullerenes: Significance of Charge Delocalization and Excess Free Energy

Despite significant improvement in power conversion efficiencies of bulk-heterojunction solar cells, the mechanism of mobile charge carrier generation is still under debate. The time-resolved microwave conductivity technique is used to investigate the mobile charge carrier generation in blends of P3HT with monoPCBM and bisPCBM by varying the excitation wavelength from the visible to NIR and the temperature from 88 to 300 K. NIR excitation corresponds to the transition of an electron from the HOMO of the P3HT directly to the LUMO of the fullerene forming the charge transfer band (CT). From the results it is inferred that the binding energy between the electron and hole in the CT state is smaller than thermal energy at 88 K (7.8 meV) that is in large contrast to previously reported values of 0.3 eV. This is ascribed to efficient charge delocalization, which increases the mean distance between the electron and hole at the interface. For P3HT:bisPCBM, the yield of charge carries decreases by a factor of 3 on ...

Rationalizing Phase Transitions with Thermal Annealing Temperatures for P3HT:PCBM Organic Photovoltaic Devices

We have studied a range of organic photovoltaic devices (OPVs) based on a thin-film blend of P3HT and PCBM and show that, by comparing device studies with a characterization of the thermal transitions of the blend, we can provide a mechanistic description of the optimum annealing temperatures necessary to improve the operational efficiency of a device. For as-cast P3HT:PCBM blend thin-films we evidence two glass transition temperatures corresponding to the existence of two compositionally different amorphous states; an observation that is unreported to date. We demonstrate that an improvement in device efficiency only occurs once the film has been heated above the upper apparent glass transition temperature of the blend. If annealing is performed above the optimum temperature, excessive phase-separation and a partial reduction in film optical density leads to a general decrease in device efficiency. Both of these characteristic temperatures are dependent upon the composition of the blend. The temperature-dependent competition between such processes therefore opens a “window” within which device efficiency can be optimized and provides an opportunity to design effective annealing protocols for future polymer:fullerene blend OPVs.

Grafting P3HT brushes on GO sheets: distinctive properties of the GO/P3HT composites due to different grafting approaches

In this study, we have grafted poly(3-hexylthiophene) (P3HT) brushes on GO sheets via a silylation reaction of the surfaces of GO sheets and a succeeding “click” reaction (GO(C)/P3HT composite). Compared with pure P3HT and the blend of P3HT and GO, the GO(C)/P3HT composite shows a red-shifted optical absorption maximum because of increased conjugation length of the grafted P3HT, which might be due to the crowding of the P3HT chains grafted on GO sheets. For comparison, P3HT chains were also grafted on GO sheets via the amidation reaction of the carboxylic acid groups (GO(A)/P3HT composite). However, the GO(A)/P3HT composite doesn't show a red shift in the UV-visible spectrum. The overall fluorescence quenching in the GO(C)/P3HT composite includes both dynamic quenching and forming a non-fluorescent ground-state complex. Additionally, thermogravimetric analysis and X-ray photoelectron spectroscopy results demonstrate that the efficiency of grafting P3HT on GO sheets via the “click” reaction approach is higher than via the amidation reaction approach. Atomic force microscopy and transmission electron microscopy observations show that the GO(C)/P3HT composite sheets are much thicker than the GO(A)/P3HT composite sheets, due to the higher grafting efficiency of the “click” reaction approach. Therefore, this work opens a novel avenue to tuning the optical properties of conjugated polymers via surface grafting chemistry.

Silicon Nanowire/P3HT Hybrid Solar Cells: Effect of the Electron Localization at Wire Nanodiameters

Photoactive hybrid films based on n type silicon nanowires [SiNWs] dispersed in poly(3-hexylthiophene) [P3HT], a p type conjugated polymer known for its good ordering properties, have a main interest for the production of photovoltaic films at a limited cost. Silicon nanowires synthesized at high yield by the oxide assisted growth technique have been dispersed in tetrahydrofuran: THF, and mixed with a P3HT solution in THF to form a blend of the inorganic-organic components in the appropriate proportions. The blend of SiNWs and P3HT have been deposited by spin coating on PEDOT-PSS/ITO substrates leading to the production of 100 nm thick SiNWs/P3HT thin layers of controlled compositions. The quenching of the P3HT fluorescence has shown the effective dissociation of the photogenerated pairs for an optimum composition of 6 SiNWs vol. % in the blend, which is in accordance with the low percolation threshold expected from the high aspect ratio of the nanowires. Current/voltage experiments under illumination have however led to collected photocurrents remaining limited to some 10 μA/cm2 whereas an interesting open circuit voltage of 0.65 V was obtained. It has been possible from surface potential decay experiments to assign the main limiting process to the low electron transport along nanowires of diameter smaller than 10 nm, whereas easy hole transport in the P3HT thickness was obtained. The high densities of silicon surface states acting as electron traps can simultaneously account for efficient charge pair dissociation and low photocurrents in nanosized structures.

Ternary behavior and systematic nanoscale manipulation of domain structures in P3HT/PCBM/P3HT-b-PEO films

Nanophase separation plays a critical role in the performance of donor–acceptor based organic photovoltaic (OPV) devices. Although post-fabrication annealing is often used to enhance OPV efficiency, the ability to exert precise control over phase separated domains and connectivity remains elusive. In this work, we use a diblock copolymer to systematically manipulate the domain sizes of an organic solar cell active layer at the nanoscale. More specifically, a poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-b-PEO) diblock copolymer with a low polydispersity index (PDI = 1.3) is added to a binary blend of P3HT and 6,6-phenyl C61-butyric acid methyl ester (PCBM) at different concentrations (0–20 wt%). Energy-filtered TEM (EFTEM) results suggest systematic changes of P3HT distribution as a function of block copolymer compatibilizer concentration and thermal annealing. X-ray scattering and microscopy techniques are used to show that prior to annealing, active layer domain sizes do not change substantially as compatibilizer is added; however after thermal annealing, the domain sizes are significantly reduced as the amount of P3HT-b-PEO compatibilizer increases. The impact of compatibilizer is further rationalized through quantum density functional theory calculations. Overall, this work demonstrates the possibility of block copolymers to systematically manipulate the nanoscale domain-structure of blends used for organic photovoltaic devices. If coupled with efficient charge transport and collection (through judicious choice of block copolymer type and composition), this approach may contribute to further optimization of OPV devices.

PCBM Disperse-Red Ester with Strong Visible-Light Absorption: Implication of Molecular Design and Morphological Control for Organic Solar Cells

A new dyad of fullerene/disperse-red, denoted as PCBDR, strongly absorbs visible light in the range of 400–600 nm. PCBDR showed advantages over PCBM in several aspects such as enhanced visible-light absorption, improved solubility, and the possibility to facilitate cascaded electron transfer. P3HT:PCBDR bulk heterojunction (BHJ) solar cells, nevertheless, so far have not outperformed P3HT:PCBM BHJ solar cells under similar conditions. Among factors that affect the efficiency of P3HT:PCBDR BHJ solar cells, the suppression of the interchain interaction of P3HT in the P3HT:PCBDR blend played a major role, presumably due to better interfacial miscibility between P3HT and PCBDR than that in blends of P3HT:PCBM. In contrast, benzoporphyrin (BP), due to its unique crystallinity, morphology, and nonsolubility, afforded a better control of the morphology and the interface of the p/n junctions. As a consequence, the performance of solar cells with BP/PCBDR as the active layer was comparable to that of BP/PCBM solar...

Bulk heterojunction and inverted type solar cells using a CN-PPV derivative

We investigated the effect of solvent on the photovoltaic performance of bulk heterojunction organic solar cells comprising of an n type polymer poly (2,5-didodecyloxy-1,4-phenylene-2-cyanovinylene-2,5-dioctyloxy-1,4-phenylene-1-cyanovinylene) (DE119) and poly(3-hexylthiophene) (P3HT). We have fabricated devices from blends of P3HT and DE119 with varying acceptor ratio cast from chlorobenzene, toluene and chloroform. For the devices with 1:2wt ratio of P3HT and DE119, respectively, cast from chlorobenzene, we achieved a short circuit current density of (JSC) of 0.85mA/cm2 and an open circuit voltage (VOC) of 1100mV with a FF of 0.33 leading to an efficiency of 0.3%. We also showed that inversion of the device can be accomplished using an amorphous titanium oxide (TiOx) as the hole blocking layer.

Performance of OPVs cells with the eutectic alloy Wood's metal used as cathode and P3HT:PC 61BM blend as active layer

OPVs cells based on the well known photoconductor polymer blends of P3HT:PC 61BM were fabricated by using Wood's metal as cathode under a vacuum free process. Wood's metal is a eutectic alloy of Pb/Bi/Cd/Sn (25%, 50%, 12.5% and 12.5%, respectively) that melts at 75 °C, and permits an easy and quick device implementation. As anode, the commercial and transparent indium tin oxide (ITO) deposited on glass slides was used. The photovoltaic performance of these OPVs cells is compared to other results reported recently in the literature, where most of the OPVs devices were fabricated by using standard methods. Our OPVs cells electrical conversion parameters: V oc = 528 mV, J sc = 7.35 mA/cm 2, FF = 0.45 and η = 1.8% are very acceptable. The metal alloy used here could make suitable the easy and fast test of mass production for solar panels.

Diketopyrrolopyrrole-Based π-Bridged Donor–Acceptor Polymer for Photovoltaic Applications

We report the synthesis, properties, and photovoltaic applications of a new conjugated copolymer (C12DPP-π-BT) containing a donor group (bithiophene) and an acceptor group (2,5-didodecylpyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione), bridged by a phenyl group. Using cyclic voltammetry, we found the energy levels of C12DPP-π-BT are intermediate to common electron donor and acceptor photovoltaic materials, poly (3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), respectively. Whereas P3HT and PCBM are exclusively electron donating or accepting, we predict C12DPP-π-BT may uniquely serve as either an electron donor or an acceptor when paired with PCBM or P3HT forming junctions with large built-in potentials. We confirmed the ambipolar nature of C12DPP-π-BT in space charge limited current measurements and in C12DPP-π-BT:PCBM and C12DPP-π-BT:P3HT bulk heterojunction solar cells, achieving power conversion efficiencies of 1.67% and 0.84%, respectively, under illumination of AM 1.5G (100 mW/cm(2)). Adding diiodooctane to C12DPP-π-BT:PCBM improved donor-acceptor inter-mixing and film uniformity, and therefore enhanced charge separation and overall device efficiency. Using higher-molecular-weight polymer C12DPP-π-BT in both C12DPP-π-BT:PCBM and C12DPP-π-BT:P3HT devices improved charge transport and hence the performance of the solar cells. In addition, we compared the structural and electronic properties of C12DPP-π-BT:PCBM and C12DPP-π-BT:P3HT blends, representing the materials classes of polymer:fullerene and polymer:polymer blends. In C12DPP-π-BT:PCBM blends, higher short circuit currents were obtained, consistent with faster charge transfer and balanced electron and hole transport, but lower open circuit voltages may be reduced by trap-assisted recombination and interfacial recombination losses. In contrast, C12DPP-π-BT:P3HT blends exhibit higher open circuit voltage, but short circuit currents were limited by charge transfer between the polymers. In conclusion, C12DPP-π-BT is a promising material with intrinsic ambipolar characteristics for organic photovoltaics and may operate as either a donor or acceptor in the design of bulk heterojunction solar cells.

P3HT:PCBM, Best Seller in Polymer Photovoltaic Research

In the fi eld of polymer-based photovoltaic cells, poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C₆₁ (PCBM) are, to date, the most-studied active materials around the world for the bulk-heterojunction structure. Various power-conversion effi ciencies are reported up to approximately 5%. This Research News article is focused on a survey of the tremendous literature published between 2002 and 2010 that exhibits solar cells based on blends of P3HT and PCBM.

Photovoltaic and impedance spectroscopy analysis of p–n like junction for dye sensitized solar cell

A dye-sensitized solar cell based on nanostructure TiO 2 and PCBM:P3HT blend was fabricated and the photovoltaic and impedance spectroscopy properties of the solar cell were investigated. The solar cell gives a short circuit current density of 0.75 mA/cm 2 and an open circuit voltage of 0.60 V under AM1.5. The photovoltage of the solar cell was greatly enhanced by PCBM:P3HT blend. The capacitance–voltage, the conductance–voltage, the series resistances–voltage characteristics of the solar cell were measured in a wide range of frequency for the first time for DSSC applications. The capacitance–voltage shows a behavior from the positive to negative capacitance due to injection of electrons from the FTO electrode into TiO 2. It is evaluated that the photovoltaic performance of the dye-sensitized solar cell can be improved using various organic semiconductors.