Realization and charactenziation of organic photovoltaic cells

Cette thèse s’insère dans un projet d’élaboration et de caractérisation des cellules photovoltaïques organiques classiques et inverses, plus précisément il s’agit d’améliorer les performances des cellules via des couches tampons anodiques et cathodiques originales. Nous avons commencé d’améliorer les couches tampons cathodiques avec différents donneurs d’électrons: phtalocyanine de cuivre CuPc, subphtalocyanine SubPc et dérivés de thiophène organiques. Dans le premier cas de donneur d’électrons (CuPc), nous avons mis en évidence l’effet d’une fine couche d’un composé de césium, utilisée comme couche tampon cathodique dans des cellules inverses, sur la collecte des électrons après un traitement thermique. Nous avons montré aussi que la couche tampon cathodique hybride, Alq3 (9nm) / Ca (3nm) améliore les performances des cellules quelque soit le donneur d’électrons et sans nécessité de recuit. Dans le cas de drivés de thiophène, nous avons montré comment la morphologie de surface des couches organiques peut influencer les performances des cellules photovoltaïques organiques. Et dans le cas de SubPc utilisé dans des cellules inverses, nous avons étudié l’effet de la vitesse de dépôt de la couche SubPc sur sa morphologie. Concernant l’amélioration de la couche tampon anodique, nous avons étudié des cellules classiques à base SubPc et du pentathiophene (5T). Après l’optimisation de l’épaisseur des donneurs d’électrons, nous avons montré que la bicouche MoO3 (3 nm) / Cul (1,5 nm) utilisée comme couche tampon anodique, permet d'améliorer les performances des cellules, quelque soit le donneur d’électrons. Dans le cas du SubPc, nous avons obtenu un rendement qui approche de 5%.This thesis concerns elaboration and characterization of classical and inverse organic photovoltaic cells, specifically improving the anodic and cathodic buffer layers. We started by improving the cathode buffer layers with different electron donors: copper phthalocyanine CuPc, subphtalocyanine SubPc and thiophene derivatives (BSTV and BOTV). In the first case of electron donor (CuPc), we highlighted the effect of the thin layer of cesium compound, used as a cathodic buffer layer in inverse cells, on the collection of electrons after heat treatment.We have also shown that the hybrid cathodic buffer layer, Alq3 (9 nm) / Ca (3nm) improves the cell performance whatever the electron donor without annealing. In the case of thiophene derivatives, we have shown how the morphology of the organic layers surface can influence the performance of organic photovoltaic cells. In the case of SubPc used in inverse cells, we studied the effect of the deposition rate of the layer on the morphology of SubPc surface.Regarding the improvement of the anodic buffer layers, we investigated those based on the SubPc and pentathiophene (5T) in classical cells. After optimization of the electron donors thickness, we have shown that the bilayer MoO3 (3 nm) / CuI (1.5 nm) used as an anodic buffer layer, improves cell performances, whatever the electron donor. In the case of SubPc, we obtained a efficiency approaching 5%

Réalisation et caractérisation des cellules photovoltaïques organiques

This thesis concerns elaboration and characterization of classical and inverse organic photovoltaic cells, specifically improving the anodic and cathodic buffer layers. We started by improving the cathode buffer layers with different electron donors: copper phthalocyanine CuPc, subphtalocyanine SubPc and thiophene derivatives (BSTV and BOTV). In the first case of electron donor (CuPc), we highlighted the effect of the thin layer of cesium compound, used as a cathodic buffer layer in inverse cells, on the collection of electrons after heat treatment.We have also shown that the hybrid cathodic buffer layer, Alq3 (9 nm) / Ca (3nm) improves the cell performance whatever the electron donor without annealing. In the case of thiophene derivatives, we have shown how the morphology of the organic layers surface can influence the performance of organic photovoltaic cells. In the case of SubPc used in inverse cells, we studied the effect of the deposition rate of the layer on the morphology of SubPc surface.Regarding the improvement of the anodic buffer layers, we investigated those based on the SubPc and pentathiophene (5T) in classical cells. After optimization of the electron donors thickness, we have shown that the bilayer MoO3 (3 nm) / CuI (1.5 nm) used as an anodic buffer layer, improves cell performances, whatever the electron donor. In the case of SubPc, we obtained a efficiency approaching 5%.Cette thèse s’insère dans un projet d’élaboration et de caractérisation des cellules photovoltaïques organiques classiques et inverses, plus précisément il s’agit d’améliorer les performances des cellules via des couches tampons anodiques et cathodiques originales. Nous avons commencé d’améliorer les couches tampons cathodiques avec différents donneurs d’électrons: phtalocyanine de cuivre CuPc, subphtalocyanine SubPc et dérivés de thiophène organiques. Dans le premier cas de donneur d’électrons (CuPc), nous avons mis en évidence l’effet d’une fine couche d’un composé de césium, utilisée comme couche tampon cathodique dans des cellules inverses, sur la collecte des électrons après un traitement thermique. Nous avons montré aussi que la couche tampon cathodique hybride, Alq3 (9nm) / Ca (3nm) améliore les performances des cellules quelque soit le donneur d’électrons et sans nécessité de recuit. Dans le cas de drivés de thiophène, nous avons montré comment la morphologie de surface des couches organiques peut influencer les performances des cellules photovoltaïques organiques. Et dans le cas de SubPc utilisé dans des cellules inverses, nous avons étudié l’effet de la vitesse de dépôt de la couche SubPc sur sa morphologie. Concernant l’amélioration de la couche tampon anodique, nous avons étudié des cellules classiques à base SubPc et du pentathiophene (5T). Après l’optimisation de l’épaisseur des donneurs d’électrons, nous avons montré que la bicouche MoO3 (3 nm) / Cul (1,5 nm) utilisée comme couche tampon anodique, permet d'améliorer les performances des cellules, quelque soit le donneur d’électrons. Dans le cas du SubPc, nous avons obtenu un rendement qui approche de 5%

Study of microstructural, morphological and optical properties of sprayed vanadium doped ZnO nanoparticles

In this paper, transparent conducting thin films based on both undoped and vanadium (V) doped zinc oxide Zn1−xVx O (x = 3, 5, 7 at.%), were studied. The thin films were prepared using a simple low cost deposition technique called spray pyrolysis (SP). The layers were deposited onto preheated glass substrates at 450 °C. The effect of vanadium on the microstructural, the morphological and the optical properties of ZnO material was carried out using X-ray diffractometer (XRD), micro Raman spectroscope, scanning electron microscope (SEM), energy dispersive analysis by X-ray (EDX) and UV-Vis-NIR spectrophotometer. We have demonstrated that doping with 3 at.% of V enhances the crystallinity of the films by estimating the grain size value, the dislocation density and the residual stress. Also, the SEM images have demonstrated that the vanadium concentrations do effect in the thin films morphology, from hexagonal-shaped grains to rounded crystals for higher doping concentrations. The optical analysis revealed that doping with 3 at.% of vanadium shows a remarkable enhancement in the average transmittance in the visible range 89% and in the band gap energy (3.3 eV). Moreover, the disorder inside the samples was estimated using Urbach equation. Therefore, the microstructural, the morphological and the optical results approve that doping with 3 at.% of V in ZnO lattices gives interesting results for the optical window material for solar cells application

Optical properties of undoped and tin-doped nanostructured In

Tin-doped indium oxide (In2O3:Sn) thin films in different concentrations (Sn = 0, 3, 5, 8 at.%) were deposited by reactive chemical pulverisation spray pyrolysis on heated glass substrates at 500 °C. The effect of the tin dopant on the nonlinear optical properties was investigated using X-ray diffraction, transmission, electrical resistivity and third harmonic generation (THG). All films were polycrystalline, and crystallised in a cubic structure with a preferential orientation along the (400) direction. The Sn (5 at.%) doped In2O3 thin films exhibited a lower resistivity of 3 × 10-4 Ω cm, and higher transmission in the visible region of about 94%. Optical parameters, such as the extinction coefficient (k), refractive index (n) and energy band gap (Eg), were also studied to show the composition-dependence of tin-doped indium oxide films. The nonlinear properties of the In2O3:Sn thin films have been found to be influenced by doping concentration, and the best value of χ(3) = 3 × 10-11 (esu) was found for the 5 at.% doped sample

Improved electron collection in fullerene via caesium iodide or carbonate by means of annealing in inverted organic solar cells

Inverted organic photovoltaic cells (IOPVCs), based on the planar heterojunction C60/CuPc, were grown using MoO3 as anode buffer layer and CsI or Cs2CO3 as cathode buffer layer (CBL), the cathode being an ITO coated glass. Work functions, Φf, of treated cathode were estimated using the cyclic voltammetry method. It is shown that Φf of ITO covered with a Cs compounds is decreased. This decrease is amplified by the annealing. It is shown that the thermal deposition under vacuum of the CBL induces a partial decomposition of the caesium compounds. In parallel, the formation of a compound with the In of ITO is put in evidence. This reaction is amplified by annealing, which allows obtaining IOPVCs with improved efficiency. The optimum annealing conditions is 150 °C for 5 min

New electron donor in planar heterojunction: optimization of the cells efficiency through the choice of the hole-extracting layer ★

International audienceDue to their light weight, flexibility and semi-transparency the organic photovoltaic cells play an important role for solar conversion photovoltaic (OPV). To achieve good performances, both donor and acceptor materials in OPVs need to have good extinction coefficients, high stabilities and good film morphologies. Since the donor plays a critical role as the absorber to solar photon flux, donor materials require wide optical absorption to match the solar spectrum. In this work the couple ED/EA in planar heterojunction was Tetracyano 4,4'-bis(9Hcarbazol-9-yl) biphenyl (TCC)/fullerene (C 60). Optimum results are obtained when MoO 3 alone is used as Hole Transporting Layer (HTL). The J/V characteristics do not exhibit S-shaped curves up to a TCC layer thickness of 15 nm, while they did when the HTL includes CuI. Theoretical study, complementary to the experimental study, shows that in the case of S-shaped curve the cell behaves as if it was made up of 2 diodes, one of which would be opposed to the flow of the photogenerated current. In the case of MoO 3 HTL, i.e; without shaped curve, the optimum thickness is 13 nm, giving an efficiency h = 2.30% with V oc = 0.9 V, J sc = 5.17 mA/cm 2 and FF = 49%

Effect of MoO3 in the cathode buffer layer on the behaviour of layered organic solar cells

The behaviour of small-molecule organic solar cells based on copper-phthalocyanine/fullerene with different cathode buffer layer is investigated as a function of air exposure duration. The effect of MoO3 on the properties of photovoltaic solar cells (OPVCs) when it is introduced in the cathode buffer layer (CBL), has been studied. Photovoltaic performances were measured as a function of time of air exposure. During the first days of air exposure, the efficiency of the OPVCs with MoO3 in their CBL increases significantly, while it decreases immediately after air exposure in the case of reference OPVCs, i.e. without MoO3 in the CBL. Nevertheless, the lifetime of the OPVCs with MoO3 in their CBL is around 60 days, while it is only 10 days in the case of reference OPVCs. The initial increase of the OPVC with MoO3 in their CBL is attributed to the slow decrease of the work function of MoO3 due to progressive contamination. Then, the progressive degradation of the OPVCs efficiency is due to water vapour and oxygen contamination of the organic layers. The use of double CBL, Alq3/MoO3, allows to interrupt the growth of pinholes, defects and increases the path of permeating gas. Also it can prevent the contamination of the organic layer by Al. All this results in significant increase of the lifetime of the OPVCs

Experimental and numerical simulation of the performance of SnS based solar cells

In the present study, the SnS thin films have been grown using the sol gel spin coating technical deposed on a glass substrate. The structural analysis of SnS thin films was examined using X-ray diffraction (DRX). The optical properties of SnS thin films have been investigated using the spectrophotometer UV-V, and we calculated the sum of the optical parameters such as the absorption coefficient, refractive index, the extinction coefficient, the real and imaginary part of the dielectric constant, and the optical conductivity. The electrical resistivity has been calculated using the four-point probe method. The performance of the SnS based proposed solar cells studied from the numerical simulation using SCAPS-1D software. The SnS-thickness, CdS-thickness, and ZnO-thickness are optimized. The SnS-band gap optimization showed that the optimal value is 1.55 eV this is similar to the value found experimentally (∼1.58 eV). The influence of the operating temperature, series and shut resistor, and SnS/CdS charge interface defect on the parameters on the performance solar cells are investigated

Improvement of pentathiophene/fullerene planar heterojunction photovoltaic cells by improving the organic films morphology through the anode buffer bilayer

International audienc

Stabilisation Attempts of the Electrical and Optical Properties of Oxide/Cu/Oxide Structures Through the Use of Different Cu:M Alloys

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