PCBM Concentration Research Articles

Induced Electron Traps via the PCBM in P(VDF-HFP) Composites to Enhance Dielectric and Energy Storage Performance.

Polymer-based composites with excellent dielectric properties are essential for advanced energy storage applications. In this work, the [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as a filler was incorporated into the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) composite to improve its dielectric performance. P(VDF-HFP) composite films with varying PCBM concentrations were prepared via solution casting and their dielectric, energy storage, and charge-discharge properties were characterized. It was found that the doped PCBM could introduce new charge traps with an energy level of 1.25 eV that modulate charge transport and energy storage characteristics of the polymer matrix. The dielectric constant of the composites was enhanced to the maximum of 10.87 as 0.2 vol% PCBM was added, while the breakdown strength reached 455 MV/m, achieving an energy density of 7.38 J/cm3, which is 33% higher than the pristine P(VDF-HFP) film. Furthermore, the charge-discharge efficiency of the composites was enhanced 66% under the electric field of 300 MV/m. These results demonstrate that PCBM significantly improves the dielectric and energy storage properties of P(VDF-HFP) composites, providing a promising approach for the development of high-performance dielectric materials in flexible energy storage devices.

Effect of PTAA and PCBM concentrations on the electrical response of bilayer heterojunction PTAA/PCBM Diode

Poly[bis(4-phenyl) (2,4,6-trimethylphenylamine] (PTAA) is a new promising hole transport material, and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) is a suitable electron acceptor material. This study deposited thin-film PTAA and PCBM at different spin coatings ranging from 1000 rpm to 5000 rpm. Ultraviolet–visible (UV–vis) spectrometer, X-ray diffraction (XRD) machine, and scanning electron microscope (SEM) techniques were used to determine the optical properties and structural properties, respectively. Thermal annealing with temperatures of 80 °C, 100 °C, 120 °C, and 150 °C was introduced to improve the properties of the PTAA and PCBM thin film. The results of SEM images for PTAA annealed at 150 °C appeared to darken and melt, whereas PCBM annealed at 120 °C and 150 °C had granule properties. The ideality factors for bilayer heterojunction diodes and bulk heterojunction PTAA/PCBM diodes with increased layers were 5.8–60.2 and 30.8–77.2, respectively. The optimum spin rate for the bilayer heterojunction PTAA/PCBM was 5000 rpm. The most appropriate diode behavior of the bilayer was at 5.0/1.0 wt%, 1.0/5.0 wt%, and 3.0/3.0 wt% of PTAA/PCBM, with the calculated ideality factors of 5.8, 6.2, and 15.45 with turn-on voltage of 1.57 V, 1.70 V, and 1.82 V, respectively.

Influence of P3HT:PCBM Ratio on Thermal and Transport Properties of Bulk Heterojunction Solar Cells.

The influence of P3HT:PCBM ratio on thermal and transport properties of solar cells were determined by photothermal beam deflection spectrometry, which is advantageous tool for non-destructively study of bulk heterojunction layers of organic solar cells. P3HT:PCBM layers of different P3HT:PCBM ratios were deposited on top of PEDOT:PSS/ITO layers which were included in organic bulk-heterojunction solar cells. The thermal diffusivity, energy gap and charge carrier lifetime were measured at different illumination conditions and with a different P3HT:PCBM ratios. As expected, it was found that the energy band gap depends on the P3HT:PCBM ratio. Thermal diffusivity is decreasing, while charge carrier lifetime is increasing with PCBM concentration. Energy band gap was found to be independent on illumination intensity, while thermal diffusivity was increasing and carrier lifetime was decreasing with illumination intensity. The carrier lifetime exhibits qualitatively similar dependence on the PCBM concentration when compared to the open-circuit voltage of operating solar cells under AM1.5 illumination. BDS and standard I-V measurement yielded comparable results arguing that the former is suitable for characterization of organic solar cells.

Effects of PCBM loading on high sensitive P3HT based vertical bulk resistive X-ray detector

Recently, semiconductive polymeric materials have attracted attention as an active layer for detecting ionizing radiation because of their excellent properties such as flexibility, easy production, solution processability and low-cost production. This paper presents X-ray detection properties of Poly(3-hexylthiophene) (P3HT):Phenyl C61 butyric acid methyl ester (PCBM) blend structure with different PCBM loading ratios. P3HT:PCBM mixing ratio was changed from 1:0 to 1:2. Top contact of the pure and blend structured device were produced by using a solution based graphite ink. Devices were constructed with vertical bulk resistive architecture within an ohmic electrode structure as ITO/PEDOT:PSS/P3HT:PCBM/Graphite configuration. Graphite electrode was coated on the active layer with the spray coating method. All devices exhibited ohmic current-voltage (I–V) characteristics. The blend structured devices exhibited stable saw-tooth type behaviour in photocurrent responses against the on and off states of X-rays. Saw-tooth type responses could be evaluated as major evidence for a potential usage of organic electronic device technology direct radiation detectors. Although the best sensitivity value to X-ray was obtained with the blend structure with equal ratio, it was observed that the rise and decay times were shortened with the increase in the amount of PCBM in the blend structure from. • P3HT:PCBM active layer based X Ray detectors were fabricated and effect of PCBM ratio was investigated. • Spray coated graphite electrode was used as the top ohmic contact for all devices. • P3HT:PCBM ratio was changed as (1:0), (1:0.5), (1:1), (1:2) and investigate PCBM concentrations how effect X Ray detection parameters with different X Ray dose rates under 10 V bias. • Best sensitivity value to X-ray was obtained with the blend structure with equal ratio of PCBM and P3HT (1:1).

Improving morphology of P3HT:PCBM bulk heterojunction solar cells with anisotropic shaped silica nanoparticles

Using coarse-grained molecular dynamics simulations we study blends of Poly(3-hexylthiophene-2,5-diyl) (P3HT), [6,6]-Phenyl-C61-butyric acid methyl ester (PCBM) and Silica nanoparticle (SiNP) to understand the effect of adding SiNP on morphology of P3HT:PCBM in Bulk heterojunction (BHJ) solar cells. We use an approximately 3 nm anisotropic shaped SiNP and predicted the morphology of BHJ upon its incorporation. The SiNP arrange themselves into anisotropic structures depending on the concentration of P3HT, PCBM and SiNP respectively creating a network like morphology. PCBM molecules utilize the surface energy of SiNP and gather at its surface forming a morphology which is beneficial for device efficiency. Our results suggest that an optimum weight fraction of all the three components leads to higher surface area of contact, optimum domain size and high percolation of domains throughout the system. The effective control of all the morphological parameters help in improving the charge generation, extraction and transport to electrodes, thereby improving the performance of BHJ solar cells.

Investigation of structural, optical and electrical properties of PCBM/ZnOEP thin films

In the present work, the spin coating technique was used to prepare the (6, 6)-Phenyl C61 butyric acid methyl ester (PCBM)/Zinc (II) octaethylporphyrin (ZnOEP) thin films by adjusting their relative ratio in blend solutions. X-ray powder diffraction (XRD) patterns assumed growth in the amorphous nature of the films with increasing PCBM concentration. Scanning electron microscopy (SEM) images clearly were showed homogeneous agglomeration. The simultaneous presence of ZnOEP and PCBM Raman modes in the Raman spectrum proved composite production. Values of the indirect-energy band gap were calculated using optical absorption measurements. The disorder in the films affected optical constants, dispersion parameters, and dielectric parameters such as dispersion energy, Ed oscillator energy Eo, plasma frequency ωp, lattice dielectric constant εL, and the carrier concentration to effective mass ratio (N/m*). The change in the charge transfer (CT) of the composite might be due to the presence of PCBM improving the nonlinear optical parameters of PCBM/ZnOEP thin films. Lastly, the dark J-V showed how changing the amount of PCBM could make the current density better. Overall, the findings for PCBM/ZnOEP thin films showed that they offer a new range of potential optoelectronic device applications.

Preparation of Pinocembrin-Loaded F127/MPEG-PDLLA Polymer Micelles and Anti-Osteoporotic Activity.

Pinocembrin (PCB) is 5,7-dihydroxyl flavanone and has multiple pharmacological activities, namely, anti-inflammation, anti-osteoporotic, and so on. However, low water solubility and bioavailability have hindered its application. Herein, we aimed to increase its bioavailability through preparation of F127/MPEG-PDLLA polymer micelles (PCB-M). We characterized the micelles through appropriate attributes such as analysis of particle size (PS), polydispersity (PDI), transmission electron microscopic (TEM) image, stability test, and evaluation of in vitro release of drug. After physical characterization, the respective PS, PDI, and entrapment efficiency (EE) of PCB-M were estimated to be 27.63 ± 0.17nm, 0.055 ± 0.02, and 90.53 ± 0.01%. Fluorescence probe method was employed to measure critical micelle concentration (CMC) of PCB-M, we observed CMC was low, thereby suggesting that PCB-M had good stability. In vitro release analysis indicated that the rate of cumulative PCB release from PCB-M was greater than 90% in each medium compared with free PCB, which was less than 40%, thus pointing to a significantly improved solubility of PCB. In vivo pharmacokinetic results showed that oral biological availability of PCB-M increased 5.3 folds comparable to free PCB. The effects of PCB on osteoblasts and ALP activities were investigated; subsequently, zebrafish osteoporotic model was established with prednisolone to study the anti-osteoporotic effects of PCB and PCB-M. The results showed that PCB improved osteoporosis with PCB-M being more effective than free PCB. Finally, PCB-M can be used as a promising method to improve the solubility of PCB, while the bioavailability and anti-osteoporotic effect of PCB could be improved, thus laying a foundation for clinical use in the future.

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.

Photoluminescence of P3HT:PCBM bulk heterojunction thin films and effect of external electric field

AbstractSteady‐state and time‐resolved photoluminescence (PL) and electrophotoluminescence (E‐PL) have been recorded for bulk heterojunction samples of thin films of regio‐regular poly(3‐hexylthiophene) (P3HT) and methyl [6,6]‐phenyl‐C61‐butanoate (PCBM). The PL spectra of the bulk heterojunction samples showed a monotonic decrease of PL quantum yield with increased PCBM content in the film. The PL decay was measured with both a femtosecond up‐conversion technique and a time‐correlated single‐photon‐counting technique. The mechanism of PL quenching deviated from a simple Stern‐Volmer equation, explained in terms of an apparent static quenching with a sphere‐of‐action model and dynamic quenching. With increased content of PCBM, the static quenching played a dominant role. Upon application of an electric field, the E‐PL spectra of both P3HT and bulk heterojunction samples showed an enhanced quantum yield and incremented lifetime of PL of P3HT. The long‐range electron transfer from P3HT to PCBM was retarded upon application of an electric field; the field‐induced change increased with increasing PCBM content.

Blend ratio and applied voltage effects on the charge recombination in bulk heterojunction polymer solar cells based on anthracene-containing poly(arylene-ethynylene)-alt-poly(arylene-vinylene) studied using magnetoconductance

We have investigated the magnetic field effect on the current in bulk heterojunction polymer solar cells made of blends of an anthracene-containing poly(arylene-ethynylene)-alt-poly (arylene-vinylene) (AnE-PVstat) and fullerene molecules prepared in various ratios (1:1, 1:2, 1:3 and 1:4) and different applied voltages ranging from 0.7 to 0.95 V in steps of 0.05 V. The efficiencies and fill factors of the resulting devices improved upon increasing the PCBM content. The highest efficiency obtained was 2.7% for the device prepared using 75% PCBM. The measured magnetoconductance (MC) is positive and monotonic over the full range of the blend ratios and applied voltages studied. We analyzed the MC effect using a magnetoconductance model controlled by interconversion of the singlet and triplet (MIST) electron-hole (e-h) pairs states based on density matrix formalism using the stochastic Liouville equation considering that the singlet and triplet e-h pairs have different recombination and dissociation rates to theoretically reproduce the line shape of MC. For all the applied voltages studied, the recombination and dissociation rates of the e-h pairs on the singlet and triplet states decreased upon increasing the fullerene content until it reached a maximum with a PCBM content of 75 wt%. After this PCBM content, the rates started to increase. However, for each blend ratio, the recombination and dissociation rates of the singlet and triplet e-h pairs increase when the voltage is increased.

Photosensitizer PCBM tuning of azo dyes-based composites: Third-order nonlinear optical properties

Abstract New organic composites with significant third-order nonlinear optical properties have potential applications in photoelectronic and photonics, such as optical limiting and optical switching. Six new azo dye-based composites have been designed and prepared. The linear optical absorption properties were studied by the UV–Vis spectrum and the band-gaps of the samples were determined using the optical method. The third-order nonlinear optical (NLO) properties were investigated by standard Z-scan. The influence of the fullerene derivative (Iliopoulos et al., 2013; Iliopoulos et al., 2013) [6, 6] -phenyl C61 butyric acid methyl ester (PCBM) on the third-order NLO properties was discussed. The third-order NLO susceptibility χ(3) increases firstly with PCBM content, then decrease afterward, and the peak appears at about 0.30 wt%. The results revealed that the third-order nonlinear susceptibility χ(3) and the molecular second hyperpolarizability γ of these composites are of the order of 10−16 (m/V)2 and 10−40 m5V−2, respectively. And the Figures Merit T and W of 1, 2, 3, 4, 5, and 6 meet the all-optical switching requirements of T 1. Hence, 1, 2, 3, 4, 5, and 6 are promising candidates for applications in all-optical switching. This work can provide a reference for design new third-order NLO materials.

Perovskite Self-Passivation with PCBM for Small Open-Circuit Voltage Loss

It is well known that [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is a common n-type passivation material in PSCs, usually used as an interface modification layer. However, PCBM is extremely expensive and is not suitable for future industrialization. Herein, the various concentrations of PCBM as an additive are adopted for PSCs. It not only avoids the routine process of spin coating the multi-layer films, but also reduces the PCBM material and cost. Meanwhile, PCBM can passivate the grain surface and modulate morphology of perovskite films. Furthermore, the most important optical parameters of solar cells, the current density (Jsc), fill factor (FF), open-circuit voltage (Voc) and power conversion efficiencies (PCE) were improved. Especially, when the PCBM doping ratio in CH3NH3PbI3 (MAPbI3) precursor solution was 1 wt%, the device obtained the smallest Voc decay (less than 1%) in the p-i-n type PSCs with poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) as hole transport layer (HTL) and fullerene (C60) as electron transport layer (ETL). The PSCs Voc stability improvement is attributed to enhanced crystallinity of photoactive layer and decreased non-radiative recombination by PCBM doping in the perovskites.

Fullerene for the Improvement of PbS QDs-Based Hybrid Solar Cells

In the present study, the hybrid photovoltaic devices based on PbS quantum dots (QDs) and poly(3-hexylthiophene-2,5diyl) have been fabricated. The effect of the insertion of [6,6]-phenyl C71 butyric acid methyl ester (PCBM) into the hybrid blend has been investigated and analyzed by using light and dark current density-voltage measurement, and impedance spectroscopy: capacitance-frequency and capacitance-voltage measurement. It is demonstrated that the introduction of PCBM into solar cells improves their efficiency with the optimal PCBM concentration of 3 wt %. It is shown that the main contribution in limitation of solar cells efficiency is brought by shallow traps induced by air exposure.

Impact of concentration variation and thermal annealing on performance of multilayer OSC consisting of sandwiched P3HT layer between PEDOT:PSS and P3HT:PCBM

In this paper, comprehensive study on variation in composition ratio and thermal annealing of multilayer organic solar cells (OSC) has been demonstrated. Our previous work reported that in comparison to the conventional OSC structure, multilayer OSC consisting of the pure donor phase between the hole transport layer and active layer has shown a significant improvement in the power conversion efficiency (PCE). Since photovoltaic performance of the OSC strongly influenced by composition ratio, the impact of poly 3-hexylthiophene (P3HT) and 6,6-phenyl-C61-butyric acid methyl ester (PCBM) weight ratio has been analyzed. It has been found that, the short-circuit current density (JSC) of the device is highest for the P3HT:PCBM composition ratio of 1.0:0.8 and decreases slightly for 1.0:1.0 weight ratio. This study has also been accompanied with the thermal annealing on spin coated P3HT:PCBM which further enhances the PCE of the device. The maximum JSC and the PCE of 9.47 mA/cm2 and 3.26% has been achieved for the multilayer OSC having P3HT:PCBM composition ratio of 1.0:0.8 and thermally annealed at 140 °C. This is attributed largely by the tuned phase morphology of the donor-acceptor. It has been found that, the P3HT:PCBM weight ratio of 1.0:0.8 results into efficient photon absorption and charge separation in the bulk heterojunction OSC. The reduced concentration of PCBM in 1.0:0.8 weight ratio leads to the strong interchain interaction of P3HT molecules which enhances the charge separation and collection ability of the bulk heterojunction OSC.

Fullerene (PCBM) Modulated MEH-PPV Photoactive Material for Plastic Solar Cells

Abstract.Plastic solar cells are promising devices in looking for low cost and flexible energy storing devices. Low efficiency is the main drawback of these cells in comparison with inorganic solar cells and hence the search for an efficient plastic solar cell has become a globally demanded research problem. In the present work we have used the modified fullerene [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) as N type modulating probe on P type semiconducting polymer Poly[2-methoxy-5-(2’-ethylhexyloxy)-phenylenevinylene] (MEH-PPV). The donor MEH-PPV polymer matrix is modulated by adding PCBM in the weight ratio 1:3, 1:1 and 3:1 in Chloro-Benzene(CB) as the common solvent and glass-coated samples are prepared by solution cast method. Samples are analyzed by UV-VISIBLE spectroscopy by JASCO UV Vis NIR V 670 spectrometer. The effect of PCBM content on MEH-PPV is to broaden the spectral response of MEH-PPV. In other words the acceptor PCBM has tuned the band gap (energy difference between HOMO & LUMO) of the donor MEH-PPV. Spectral analysis revealed that 1:3 blend of MEH-PPV with PCBM has a wide spectral sensitivity for absorption. The band gap for each blend is determined using Tauc’s plot. Increased Fullerene content has decreased the band gap of the host polymer. We conclude that modified fullerene can effectively modulate the donor polymer matrix and 1:3 MEH-PPV: PCBM can act as a good photoactive material for solar cells. Absorption can be further enhanced by either dye sensitization or by metal oxide nanoparticle doping without increasing the thickness of the film. We have doped the optimized 1:3 blend with 20%, 40% & 60% of TiO2 nanoparticles wherein the absorption is enhanced with doping level. The increased absorption is attributed to the photocatalytic activity of the nanaoparticles embedded in the polymer matrix

Energy level alignment and interfacial dipole layer formation at the P3HT:PCBM-Electrolyte interface in organic photoelectrochemical cells

The influence of PCBM on the electronic energy levels of P3HT:PCBM photocathodes was investigated in a non-aqueous electrolyte using a benzoquinone redox couple. The presence of PCBM introduces a density of interface states at the semiconductor-electrolyte interface, consequently leading to the formation of an interfacial dipole layer and decrease in the built-in potential developed at the semiconductor-electrolyte interface. Photoelectrochemical measurements reveal a decrease in photovoltage from 0.26 V to 0.16 V and cathodic shift in onset potential from -0.27 V to -0.34 V (vs. Ag/Ag+) as PCBM content of the P3HT:PCBM photocathode is increased from 0 through 50 wt%. Additionally, depletion layer widths decreased from 90 nm to 50 nm. When the thickness of the active layer was controlled to coincide with the depletion layer thickness (e.g., 90 nm), photocurrent densities at pristine P3HT photocathodes were found to be higher than for P3HT:PCBM photocathodes. This suggests that the built-in electric field within the active layer is seemingly capable of effective exciton dissociation in the absence of a fullerene acceptor.

Investigation of non-linear dependence of exciton recombination efficiency on PCBM concentration in P3HT:PCBM blends

A systematic study of the photoluminescence quenching efficiencies in P3HT: PCBM blends showed a non-linear dependence on the PCBM concentration. We find a faster decrease in PL emission initially which later flattens out around 1:1 composition which tallies well with sample compositions known to give the best power conversion efficiencies. This implies that the exciton dissociation rates dominate the photocurrent generation in these films. We obtained a maximum of 91% photoluminescence quenching for films with a 1:1 blend ratio. A mean field based phenomenological model is presented, which very well describes our experimental results. The generation of free carriers due to various proposed mechanisms like dissociation and delocalization are collectively considered in the model. The model helps us understand the underlying physics and dependence of the quenching efficiency on parameters like excitation intensities. The proposed model will be useful in predicting the behaviour of exciton dissociation in new organic blends.

Elaboration of PCBM Coated P3HT Nanoparticles: Understanding the Shell Formation

Solvent displacement, or nanoprecipitation, is a well-known process to develop colloidal dispersions in water. Using two successive and selective nanoprecipitation steps, we developed a method to generate [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) shell on poly(3-hexylthiophene) (P3HT) core nanoparticles (P3HT@PCBM). We report herein on the understanding of the shell formation during this process. Using several techniques (dynamic light scattering, zeta-potential, photoluminescence), we evidenced that after the first solvent displacement with dimethyl sulfoxide (DMSO), the PCBM molecules still dissolved in the medium are already in close interaction with the P3HT nanoparticles (NP). Such proximity of the P3HT core with PCBM molecules in the DMSO dispersion explains why PCBM aggregates around the nanoparticles during the second solvent displacement with water. A fast electron transfer from P3HT to PCBM was identified by transient absorption spectroscopy, confirming the core-shell morphology even for low PCBM concentration. This study opens the route for the development of well-defined nano-objects dispersed in water for fabrication of organic photovoltaic devices with eco-friendly processes.

Influence of blending ratio on resistive switching effect in donor-acceptor type composite of PCBM and PVK-based memory devices

Abstract The influence of blending ratio on resistive switching effect in donor-acceptor type composite of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly(N-vinylcarbazole) (PVK)-based memory devices are investigated. Current-voltage (I-V) curves for the ITO/PCBM + PVK/Al devices with 9 wt.% of PCBM showed a current bistability with a maximum OFF/ON resistance ratio of 9 × 104, which was 100 times larger than that of the device with 23 wt.% of PCBM and was 2000 times larger than that of the device with 41 wt.% of PCBM. Furthermore, the threshold voltage obviously decreased as the PCBM concentration increases. The retention time was above 105 s indicative of the memory stability of the as-fabricated devices. The I-V characteristics at OFF state dominantly comply with the rules of space-charge-limited-current behaviors, and I-V curve at ON state obey Ohmic laws. The proposed device suggests a promising approach for adjustale OFF/ON resistance ratio and threshold voltage in electronic memory devices.

Neutron reflectometry and hard X-ray photoelectron spectroscopy study of the vertical segregation of PCBM in organic solar cells

The composition of the active layer of a benchmark functional glass/ITO/[P3HT:PCBM][1.1:1]/Al organic solar cell has been studied by neutron reflectometry (NR) and hard X-ray photoelectron spectroscopy (HAXPES). Thermal annealing was performed in several steps and NR and HAXPES were recorded for every temperature. By fitting the NR results to a model composed of several layers, the scattering length density (SLD) distribution through the sample was obtained, and from this SLD profile, the evolution of the composition of the active layer as a function of temperature was established. For the outer layers, HAXPES results confirm the composition evolution. The results show that PCBM tends to segregate reducing the initial concentration of PCBM in the central part of the active layer and increasing its concentration towards both interfaces. The effect of the Al electrode as studied by HAXPES on the nearest zone of the active layer (up to 50 nm) is to stabilize the P3HT depletion in this area, an effect which is not affected by thermal annealing.