C61-butyric Acid Methyl Ester Research Articles

Ternary atoms alloy quantum dot assisted hole transport in thin film polymer solar cells

Quantum confinement effects and multiple exciton generation (MEG) were explored in this investigation to assist the hole transport and improved trapping of light in thin film solar cells (TFOSCs). The popular organic transport material Poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT:PSS) is employed here for effective electron blocking and hole transport processes through doping with quantum dots (QD). Alloyed CdTeSe QD is used, at different concentrations, in PEDOT:PSS layer to fabricate TFOSCs in the convectional device structure consisting of molecules blended as poly (3-hexylthiophene): (6, 6)-phenyl- C61-butyric acid methyl ester (P3HT: PCBM) solar absorber. A remarkable increase in performance of the devices was achieved from TFOSC whose HTL doped with QDs that resulted in an optimal boost in power conversion efficiency (PCE) as high as 111.7% relative to the reference cell. The results suggest that the doping of HTL with the alloy of CdTeSe quantum dots assisted in electron blocking, and improved hole collection as well as improved light trapping at the interface between the solar absorber layer and HTL.

A step-by-step strategy to enhancing the photovoltaic performance of indandione-based polymers

A series of conjugated polymers, poly(2-(5-hexylthiophen-2-yl) methylene-1H-indene-1,3(2H)-dione benzodithiophene) (IND-HT-BDT) and poly(2-(5-hexylthiophen-2-yl) methylene-1H-indene-1,3(2H)-dione fluorinated benzodithiophene) (IND-HT-BDTF), based on 1,3-indandione derivatives are designed and synthesized for organic solar cells (OSCs). The polymers have a typical architecture of donor – acceptor (D-A) configurations with 2-(5-hexylthiophen-2-yl) methylene-1H-indene-1,3(2H)-dione (IND-HT) as the electron acceptor and the benzodithiophene (BDT) or fluorine substituted benzodithiophene (BDTF) as the electron donor. To investigate the photovoltaic properties of the polymers as the polymer donor, inverted OSCs are fabricated based on the polymer as the donor and fullerene acceptor (6,6)-Phenyl C71 butyric acid methyl ester (PC71BM) or 2,2'-((2Z,2'Z)-((12,13-bis(2-butyloctyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno [2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis (methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)) dimalononitrile (Y6BO). IND-HT-BDT and IND-HT-BDTF based devices as the polymer donors and Y6BO exhibit the power conversion efficiency (PCE) of 4.82% and 6.43%, respectively, which are better than the corresponding devices based on PC71BM as the acceptor. This is due to the complementary absorption ranges between donor polymers and those Y6BO acceptors.

An insight into interchain charge transfer through a photophysical study of purified conjugated nanoparticles system

Polymer nanoparticles are an attractive materials system for photovoltaic application, and their underlying photo conversion mechanism is vital for designing organic nanoparticles-based solar cells. In this work, we report the synthesis of two different nanoparticle systems, namely intra-dyad and inter-dyad containing electron-donating material Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT) and electron-accepting molecule [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) fabricated through mini-emulsion technique and optically characterized by Ultraviolet–Visible Spectroscopy (UV–Vis). The observed bathochromic redshift indicates molecular aggregation. Intra-dyad nanostructures have been made to optimize surface coverage and diffusion length for better charge transport and photo-physical optimization. Time-correlated single-photon counting (TCSPC) shows shortening of the lifetime of the excited state in the intra-dyad nanoparticle system, which leads to the fast charge transfer from donor to acceptor molecules. Atomic force microscopy (AFM) has been performed on spin-coated NPs to investigate the morphological characteristics of the active layers of the two approaches.

The nature of excitons in PPDT2FBT:PCBM solar cells: Role played by PCBM

In organic semiconductor-based bulk heterojunction solar cells, the presence of an acceptor increases the formation of charge-transfer (CT) excitons, thereby leading to higher exciton dissociation probabilities. In this work we used steady-state electroabsorption (EA) measurements to probe the change in the nature of excitons as the blend composition of the solar cell active layer material was varied. We investigated blends of poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c]-[1,2,5]thiadiazole)] (PPDT2FBT) and (6,6)-phenyl C71 butyric acid methyl ester (PCBM). Analysis of the EA spectra showed that in the presence of a fullerene-based acceptor, like PCBM, CT characteristics of the excitons were modified, though no new CT signature was observed in the blend. Enhancement in the CT characteristics in the blend was reflected in photoluminescence (PL) measurements of the blends, where PL quenching of ∼63% was observed for 1% PCBM. The quenching reaches saturation at about 20% PCBM. However, efficiency of the device increased with a PCBM percentage beyond 20%. Maximum efficiency was obtained for the blend with 50% PCBM, among the blend compositions studied in this work, indicating the optimum concentration of PCBM for best power conversion efficiency to be around that value. When we compared the experimental results with simulations, the variation of the device efficiency with PCBM percentage was shown to arise from multiple factors, such as an increase in the polarizability and dipole moment of excitons, and the efficiency of the carrier collection from the bulk of the active layer.

Silver doped ZnS core-shell nanocomposites to promote photon harvesting in polymer cells

Silver doped zinc sulfide (ZnS:Ag) metal nanoparticles (NPs) were successfully synthesized and used as a dopant in thin-film organic solar cells (TFOSCs). Core-shell structured ZnS:Ag nano-particle is expected to improve photon harvesting in solar absorber medium. Polymers blend composed of poly-(3-hexylthiophene) (P3HT): [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) were used as absorber medium with and without ZnS:Ag metal NPs. The concentrations of the metal NPs were varied to investigate the effect of doping level in the generation photocurrent. Significant device performances were recorded with short-circuit current (Jsc) of 14.30 mAcm−2, fill factor (FF) of 52.63%, and PCE performance of 4.50% was achieved at 3% concentration by weight. Such an improvement is likely attributed to the presence of localized surface plasmonic resonance (LSPR) effect at the metal/polymer interfaces, which plays an essential role in augmenting the charge transport processes and augmenting the optical absorption. The results further indicate that PCE value has enhanced dramatically by 98% compared to the pristine reference cell. The finding of our investigation will be deliberated based on the measured optoelectronic and morphological properties of newly synthesized ZnS:Ag metal NPs and device performances.

Enhancement of resistive switching behavior of organic resistive random access memory devices through UV-Ozone treatment

We fabricated organic resistive random-access memory (RRAM) devices using a low-cost solution-process method. All the processes were performed at temperatures below 135 °C under ambient atmospheric conditions. The RRAM resistive switching layer was formed from a polymer-fullerene bulk heterojunction using poly(3-hexylthiophene-2,5-diyl) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM). The fabricated organic RRAM device exhibited typical nonvolatile bipolar resistive switching behavior with an ON/OFF ratio of ∼40, but it provided a low endurance of 27 cycles. Therefore, for enhanced stability, simple UV–Ozone (UVO) treatment was applied to the P3HT:PCBM organic bulk heterojunction layer. The organic RRAM device with UVO treatment exhibited an enhanced performance with an ON/OFF ratio of ∼400 and an endurance of 47 cycles. In addition, complementary resistive switching behavior was observed. The conduction mechanisms of the organic RRAM device were investigated by fitting the measured I–V data to numerical equations, and Schottky emission and Ohmic conduction were the main conduction mechanisms for the high-resistance and low-resistance states for the RRAM device with or without UVO treatment.

Submolecular Resolution Imaging of P3HT:PCBM Nanostructured Films by Atomic Force Microscopy: Implications for Organic Solar Cells.

The efficiency of organic bulk-heterojunction (BHJ) solar cells depends greatly on both the bulk and surface structure of the nanostructured bicontinuous interpenetrating network of materials, known as the active layer. The morphology of the top layer of a coated film is often resolved at the scale of a few nanometers, but fine details of the domains and the order within them are more difficult to identify. Here, we report a high-resolution atomic force microscopy (AFM) investigation of various stoichiometries of the well-studied poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM) active layer mixture. Images of the surface were obtained using AC-mode AFM exciting higher-order resonance frequencies of a standard silicon probe, a promising technique for acquiring real-space images of organic-based thin films with nanoscale and even submolecular resolution. We provide firm evidence of the nanoscale organization of the P3HT polymer and of the P3HT:PCBM stoichiometric mixtures at the surface-air interface of the BHJ architecture. Our study shows the characteristic periodicity of the regioregular P3HT identified in the nanoscale domain areas with submolecular resolution. Such areas are then distorted in place when adding different quantities of PCBM forming stoichiometric mixtures. When the samples were exposed to ambient light, the morphologies were very different, and submolecular resolution was not achieved. This approach is shown to provide a precise view of the active layer's nanostructure and will be useful for studies of other materials as a function of various parameters, with particular attention to the role of the acceptor in tuning morphology for understanding optimum performance in organic photovoltaic devices.

Reducing the interfacial voltage loss in tin halides perovskite solar cells

Tremendous attention has been given to tin halide perovskite solar cells (TPSCs) due to the lower toxicity and similar electronic configuration compared with the lead perovskites. Nevertheless, on account of the intrinsic low bandgap, high defect density and surface/interface non-radiative recombination, the open-circuit voltage loss (Vloss) of TPSCs is comparatively large in all semiconductor solar cells. Herein, a hydrophobic bulky molecule of 3-(trifluoromethyl) phenethylamine hydroiodide (CF3PEAI) was utilized to passivate the lead-free perovskite surface by post-deposition treatment. The Vloss of the corresponding PSC devices was significantly reduced to afford a high open-circuit voltage (Voc) up to 0.73 V with a power conversion efficiency (PCE) of 10.35% in conjunction with the broadly utilized (6,6)-Phenyl C61 butyric acid methyl ester (PC61BM). Additionally, the CF3PEAI interlayer expressively suppressed the interfacial non-radiative recombination accompanying with extending photoexcited carrier lifetime. The formation of oriented 2D Sn-based perovskite could also facilitate the vertical charge-carrier transportation and improve the efficiency of Sn-based PSCs. The density of defect states and the amount of mid-gap states required to be filled were both dramatically reduced. Meanwhile, the surface reconstruction can effectively relax the tensile surface strain with the phenethyl ammonium iodide ligands. Therefore, this surface passivation strategy contributes to the development of high-quality lead-free perovskite film with low internal defects and residual stress.

Synthesis and Reactivities of Conducting Hexathienylbenzene-Co-Poly(3-Hexylthiophene) Star-Branched Copolymer as Donor Material for Organic Photovoltaic Cell

The hexathienylbenzene-co-poly(3-hexylthiophene-2,5diyl) (HTB-co-P3HT) conducting polymer was synthesized by oxidative co-polymerization of hexathienylbenzene (HTB) and 3-hexylthiophene using iron chloride (FeCl3) as an oxidant. The effect of chlorobenzene, toluene and chloroform on the optoelectronic characteristics of the polymer was investigated. The study revealed that spectroscopic and electrochemical responses of HTB-co-P3HT are affected by the nature of the solvent. The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels of HTB-co-P3HT were determined from cyclic voltammetry (CV) and were compared to those of (6,6)-Phenyl C71 butyric acid methyl ester (PC71BM) and it was found that the LUMO energy levels of HTB-co-P3HT in toluene were lower than those for chlorobenzene and chloroform. The electrochemical impedance spectroscopy (EIS) analysis also revealed the thin film of HTB-co-P3HT prepared using toluene as the most conductive. However, the photovoltaic parameters of the HTB-co-P3HT organic photovoltaic cells (OPVs) departed from the favored toluene and noted chlorobenzene as being the advantageous solvent. We obtained a power conversion efficiency (PCE) of 0.48%, fill factor (FF) of 27.84%, current density (JSC) of 4.93 mA.cm−2 and open circuit voltage (VOC) of 0.35 V in chlorobenzene, a PCE of 0.30%, FF of 26.08%, JSC of 5.00 mA.cm−2 and VOC of 0.23 V in chloroform and finally, a PCE of 0.33%, FF of 25.45%, JSC of 5.70 mA.cm−2 and VOC of 0.23 V in toluene.

Photorefractive Response Enhancement in Poly(triarylamine)-Based Polymer Composites by a Second Electron Trap Chromophore.

Photorefractive (PR) performances are affected by the components of the photoconductor, sensitizer, nonlinear optical dye, and plasticizer. A photoconductor with high hole mobility promises a faster response time, whereas it induces higher photoconductivity, which leads to easy dielectric breakdown. Adding a second electron trap is effective in controlling photoconductivity. In this study, the role of a second electron trap 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB) was investigated in a PR composite consisting of a photoconductor of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] with a high hole mobility, a nonlinear optical chromophore of piperidinodicyanostyrene, a plasticizer of (2,4,6-trimethylphenyl)diphenylamine, and a sensitizer of [6,6]-phenyl C61 butyric acid-methyl ester. The minimum time response with the maximum optical diffraction efficiency and sensitivity was measured at a 1 wt % content of TmPyPB. These results were consistent with the number of charge carriers trapped per unit volume and per unit time Nc (cm–3 s–1), which is defined as the ratio between the initial trap density Ti (cm–3) and response time τ (s), at a 1 wt % content of TmPyPB. A faster response time of 149 μs, optical diffraction of 24.1% (external diffraction of 4.8%), and a sensitivity of 2746 cm2 J–1 were measured at 50 V μm–1 for the sample with 1 wt % TmPyPB. High loading of 5 wt % TmPyPB led to a large decrease in photoconductivity and effectively suppressed the dielectric breakdown under a stronger electric field, whereas a slower response time with lower diffraction efficiency was observed for optical diffraction.

Photoluminescence of melanin-based nanocomposites with fullerene derivative

This paper presents the study of the photoluminescent properties of molecular compositions consisting of melanin and an electron-acceptor material – fullerene derivative, [6,6]-phenyl C61 butyric acid methyl ester (PCBM). These molecular compositions have not been studied well and are promising for molecular electronics of natural materials, in particular, for organic solar cells. The novelty of this work relates to the study of photoluminescence spectra obtained for these molecular compositions and nanocomposites in various solvents (chloroform, acetonitrile, and toluene) as well as in a polystyrene matrix; these studies were carried out at various, in particular, liquid helium (4.2 K), temperatures. The obtained results allowed us to ascertain mechanisms of the state of aggregation and donor-acceptor interaction between melanin and PCBM.

Plasmon assisted optical absorption and reduced charge recombination for improved device performance in polymer solar cell

Silver and Calcium (Ag:Ca) bi-metallic nano-partices have been successfully synthesized using a chemical reduction processes. The nano-partices were intended to be used in the solar absorber layer of thin film organic solar cell (TFOSC) to assist in improving optical absorption and charge transport processes in polymers blend medium. The nanocomposite (Ag:Ca) is expected to exhibit local surface plasmon resonance (LSPR) and far-field scattering from the interaction with the incident photons. The absorber layer of TFOSC, in this investigation, is prepared from the mixture of poly-(3-hexylthiophene) (P3HT): [6,6]-phenyl C61 butyric acid methyl ester (PC61BM). Devices were fabricated at various concentration of metal nano-particles in the solar absorber layer, as 1%, 3%, and 5% by weight, to be able to determine the optimum concentration of the dopant. Hence, the experimental evidences clearly showed that performance of the solar cell is dependent on the concertation of the metal nano-particles. Consequently, the power conversion efficiency (PCE) value has increased by 75% with a remarkable improvement in device fill factor of 53.4% at an optimum doping level of 3%. The optical and morphological properties of the synthesized nano-particles are well presented and discussed in terms of the data collected using transmission and scanning electron microscopy (TEM & SEM) and other complimentary methods.

Organic bulk heterojunction solar cells spin-coated in ambient environment on flexible and glass substrates

Organic solar cells based on Poly (3-hexylthiophene) [6,6]-phenyl C61-butyric acid methyl ester (P3HT-PCBM) were fabricated in standard architecture by spin-coating on glass and on flexible polyethylene terephthalate (PET) substrates in ambient laboratory environment. In addition to the conventional DC characterization, impedance spectroscopy was used in order to study the capacitive behavior of the devices and obtain their electrical parameters. In combination with the electrical characterization methods, laser-beam-induced current (LBIC) measurements were used as a non-destructive method of mapping the photocurrent distribution and analyzing local device failures and macroscopic defects (shunts, dark spots, defects). The results of the study can be used to develop guidelines for the development and design of P3HT:PCBM solar cells in ambient environment.

A “green” all-organic heterostructure functionalized by self-assembled fullerene small molecule with enhanced photocatalytic activity

Photocatalysis has been reported as a potential water purification technology for combating the pathogenic bacteria and degrading the hazardous chemicals. The photoactive organic semiconductors as the emerging class of an alternative to the traditional developed inorganic semiconductors are being widely pursued due to their tunable structures and low toxicity. Herein, the all-organic [6,6]-phenyl C71 butyric acid methyl ester (PC71BM)/g-C3N4 heterostructure have been created by introducing self-assembled n-type fullerene small molecule to the g-C3N4 surface in situ. The absorption edge of the heterostructures with PC71BM as the photosensitizer extend from 450 to 650 nm. Moreover, the charge separation and transfer efficiencies of the photocatalysts are greatly promoted even with 1.0% amount of PC71BM because of its low reorganization energy and high reduction potential. All of these superiorities endow the heterostructures with over 99.7% antibacterial rates toward E. coli and S. aureus and excellent performance against their biofilms after irradiation for 135 and 180 min, respectively. Additionally, the heterostructures achieve excellent photocatalytic degradation ability for Rhodamine B and tetracycline. Importantly, the in vitro experiments reveal that the as-prepared heterostructures possess satisfactory biocompatibility and their toxicity is negligible. This study provides a new perspective for designing ecofriendly all-organic heterostructures with high photocatalytic activity.

Conception and Theoretical Study of a New Copolymer Based on MEH-PPV and P3HT: Enhancement of the Optoelectronic Properties for Organic Photovoltaic Cells.

A new copolymer has been studied, which is formed by Poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) and poly(3-hexylthiophene) (P3HT). The choice of these π-conjugated polymers was based on their semiconductor characters and their great applicability in electronic organic devices. The structure and vibrational and optoelectronic properties were simulated by calculations based on DFT, TD-DFT, and ZINDO. This material shows original and unique properties compared to the basic homopolymers. Thus, the obtained results reveal that this copolymer can be mixed with the (6,6)-phenyl C61 butyric acid methyl ester (PCBM) to give existence to a new composite that can be used as an active layer for an organic solar cell.

Liq interlayer as electron extraction layer for highly efficient and stable perovskite solar cells

Halide perovskite solar cells (PSCs) have gained enormous attention due to their favorable features such as bandgap tunability, considerable free carrier diffusion length, low-cost fabrication, and comparable efficiency to that of conventional silicon solar cells. Among several PSCs' structures, the inverted structure is the most suitable candidate for diverse portable applications since they can take advantage of the previously developed organic solar cells' structure. However, the single transporting layer system of the inverted-structured PSCs makes it challenging to achieve high efficiency and operational stability. Here, we introduce a unique transporting layer system that adopts 8-hydroxyquinolinolato-lithium (Liq) as a buffer layer at the interface between [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) and Ag electrode. By introducing the Liq, we effectively decreased the potential energy barrier and iodide accumulation at the interface between PC70BM and Ag electrode, which resulted in an efficient and stable PSC. In the optimized structure, the power conversion efficiency and stability (T80) increased from 9.5% and 100 h to 10.13% and 200 h, respectively.

Correlation of Changes in Electronic and Device Properties in Organic Photovoltaic with Exposure to Air

AbstractIn polymer‐based organic photovoltaic cells, the capability of charge extraction/injection of molybdenum trioxide (MoO3) is demonstrated as interface layer for polymer bulk heterojunction (BHJ). The present work determines the dipole formed at the MoO3 and conjugated poly [2,3‐bis (3‐octyloxyphenyl) quinoxaline‐5,8‐diyl‐alt‐thiophene‐2,5‐diyl] (TQ1):(6,6)‐Phenyl C71 butyric acid methyl ester (PC71BM) bulk heterojunction interface. This dipole has a major influence on the charge transport across the TQ1:PC71BM interface. The formation of the dipole is determined with electron spectroscopy and the depth profiling technique neutral impact collision ion scattering spectroscopy. Metastable induced electron and UV‐photoelectron spectroscopy is applied to determine the enclosed surface coverage of minimum 1.5 nm MoO3 and a maximized dipole strength of 2.4 eV with >2 nm MoO3 deposition on BHJ. It is also demonstrated that the air exposure reduces the dipole at the interface and leads to a decrease in cell performance providing evidence that the dipole formed at the interface is beneficial for the functioning of photovoltaic cells. The results indicate that the reduction in dipole might not be the only mechanism leading to cell performance degradation. The findings of the present work have relevance for other BHJ systems because MoO3 as high work function material is likely to interact with other organic materials in a similar way.

Molecular Weight Tuning of Organic Semiconductors for Curved Organic-Inorganic Hybrid X-Ray Detectors.

Curved X‐ray detectors have the potential to revolutionize diverse sectors due to benefits such as reduced image distortion and vignetting compared to their planar counterparts. While the use of inorganic semiconductors for curved detectors are restricted by their brittle nature, organic–inorganic hybrid semiconductors which incorporated bismuth oxide nanoparticles in an organic bulk heterojunction consisting of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and [6,6]‐phenyl C71 butyric acid methyl ester (PC70BM) are considered to be more promising in this regard. However, the influence of the P3HT molecular weight on the mechanical stability of curved, thick X‐ray detectors remains less well understood. Herein, high P3HT molecular weights (>40 kDa) are identified to allow increased intermolecular bonding and chain entanglements, resulting in X‐ray detectors that can be curved to a radius as low as 1.3 mm with low deviation in X‐ray response under 100 repeated bending cycles while maintaining an industry‐standard dark current of <1 pA mm−2 and a sensitivity of ≈ 0.17 μC Gy−1 cm−2. This study identifies a crucial missing link in the development of curved detectors, namely the importance of the molecular weight of the polymer semiconductors used.

Impact of the reverse bias voltage on the lifetime of polymer solar cells

We report an investigation into the impact of applying a large reverse bias voltage during current–voltage (J-V) sweeps on the degradation rate of solar cells based on poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6-6]-phenyl C71-butyric acid methyl ester (PC70BM), under air mass 1.5 simulated solar irradiation. The degradation rate was found to be significantly slower when devices were characterized using frequent J-V sweeps with a large reverse bias component (-7 V to 1 V), with a decrease in power conversion efficiency of 24% after ∼ 100 hrs of light exposure. In contrast, devices scanned from −1 V to 1 V degrade by 72% in the same time period. The decay in the photovoltaic performance was found to be related to an increase in the series resistance and a decrease in the shunt resistance of the devices over time. Further characterization of the bulk heterojunction layer under irradiation conditions indicates that this behavior might be caused by the decreasing mobility of the charge carriers due to the formation of the defects or traps in the layer, induced by the photo-oxidation process. The frequent application of a large reverse bias sweep most likely helps de-trap the charge carriers and slows down the device degradation. Impedance analysis indicated that during the decay of PCDTBT:PC70BM devices the bulk layer became more resistive with time, and applying large and frequent reverse bias sweeps during testing could significantly slow down this process. The charge carrier extraction time was found to increase from 7 μs to more than 400 μs after photo-degradation. These findings demonstrate that repeated application of a reverse bias voltage can affect device degradation, and therefore that the specific details of J-V characterization should be reported alongside device lifetime claims.

Bimetallic core-shell nanoparticles to improve the absorption of P3HT: PCBM organic solar cell.

In this paper, we have theoretically studied a poly (3-hexylthiophene): 6,6-phenyl C61-butyric acid methyl ester (P3HT: PCBM) organic solar cell with randomly dispersed bimetallic nanoparticles. We have considered bimetallic core-shell Ag-Au nanoparticles as scattering centers randomly distributed among the active layer of a P3HT: PCBM solar cell. To study the role of Ag-Au nanoparticles, we have used the effective medium theory. The extinction and scattering cross sections of core-shells have been calculated based on the extended Mie theory. The scattering cross section of the active layer has been calculated by combining the extended Mie theory with the effective medium theory. The calculated current-voltage curve of solar cells has been compared with the experimental data of similar works to check the model's validity. In the optimized situation, it shows good agreement with experimental data, and we have obtained about 59% enhancement in the short circuit current of the solar cell.