Main objective of the present work is to develop wide-band gap InGaN solar cells in the 2.4 - 2.9 eV range that can be an integral component of photovoltaic devices to achieve efficiencies greater than 50%. In the present work, various challenges in the novel III-nitride technology are identified and overcome individually to build basic design blocks, and later, optimized comprehensively to develop high-performance InGaN solar cells. Due to the unavailability of a suitable modeling program for InGaN solar cells, PC1D is modified up to a source-code level to incorporate spontaneous and piezoelectric polarization in order to accurately model III-nitride solar cells. On the technological front, InGaN with indium compositions up to 30% (2.5 eV band gap) are developed for photovoltaic applications by controlling defects and phase separation using metal-organic chemical vapor deposition. InGaN with band gap of 2.5 eV is also successfully doped to achieve acceptor carrier concentration of 1e18 cm-3. A robust fabrication scheme for III-nitride solar cells is established to increase reliability and yield; various schemes including interdigitated grid contact and current spreading contacts are developed to yield low-resistance Ohmic contacts for InGaN solar cells. Preliminary solar cells are developed using a standard design to optimize the InGaN material, where the band gap of InGaN is progressively lowered. Subsequent generations of solar cell designs involve an evolutionary approach to enhance the open-circuit voltage and internal quantum efficiency of the solar cell. The suitability of p-type InGaN with band gaps as low as 2.5 eV is established by incorporating in a solar cell and measuring an open-circuit voltage of 2.1 V. Second generation InGaN solar cell design involving a 2.9 eV InGaN p-n junction sandwiched between p- and n-GaN layers yields internal quantum efficiencies as high as 50%; while sixth generation devices utilizing the novel n-GaN strained window-layer enhance the open circuit voltage of a 2.9 eV InGaN solar cell to 2 V. Finally, key aspects to further InGaN solar cell research, including integration of various designs, are recommended to improve the efficiency of InGaN solar cells. These results establish the potential of III-nitrides in ultra-high efficiency photovoltaics.

Η ηλιακή ενέργεια στο σύνολό της είναι πρακτικά ανεξάντλητη, και είναι η κυριότερη μορφή ανανεώσιμης πηγής. Η ηλιακή ακτινοβολία παρέχει ένα τεράστιο ποσό ενέργειας στη Γη. Τα ηλιακά φωτοβολταϊκά στοιχεία, γνωστά ως "φωτοβολταϊκά" ή "Φ/Β", αποτελούν μία προσέγγιση υψηλής τεχνολογίας για την άμεση μετατροπή του ηλιακού φωτός σε ηλεκτρική ενέργεια. Κατα τη διάρκεια αυτής της διπλωματικής εργασίας έγινε μια αναλυτική περιγραφή του τρόπου λειτουργίας τους και ιδιαίτερα υπό συνθήκες χαμηλής συγκέντρωσης. Πιο συγκεκριμένα, στο 1ο Κεφάλαιο γίνεται μια εισαγωγή στις ανανεώσιμες πηγές ενέργειας και ιδιαίτερα στην ηλιακή. Παρουσιάζεται η εξέλιξη των Α.Π.Ε. στον ελλαδικό χώρο και οι αιτίες που έστρεψαν τον άνθρωπο σε νέες μορφές ενέργειας πέραν τον ορυκτών καυσίμων. Στο Κεφάλαιο 2 γίνεται αναφορά στη θεωρία της Ηλιακής Γεωμετρίας που συνδέεται με τις δυο κύριες κινήσεις της Γης, την ημερήσια περιστροφή της και την ετήσια γύρω από τον Ήλιο. Παρουσιάζονται θεωρητικά μοντέλα πρόβλεψης της ηλιακής ακτινοβολίας και σχέσεις υπολογισμού της σε επιφάνειες στο επίπεδο της Γης. Στο Κεφάλαιο 3 παρουσιάζεται μια σύντομη περιγραφή της λειτουργίας των φωτοβολταϊκών κυττάρων και των φυσικών ιδιοτήτων αυτών των ημιαγώγιμων διατάξεων. Επίσης γίνεται λόγος για τις υπάρχουσες τεχνολογίες φωτοβολταϊκών με τα πλεονεκτήματα και τα μειονεκτήματά τους και για διάφορα φαινόμενα που επηρεάζουν τη λειτουργία τους. Το Κεφάλαιο 4 είναι αφιερωμένο στα συγκεντρωτικά συστήματα και σε όλες τις υπάρχουσες γεωμετρίες που χρησιμοποιούνται αυτή τη στιγμή και ιδιαίτερα στη γεωμετρία του V-Trough που χρησιμοποιήθηκε στο πειραματικό σκέλος. Επίσης γίνεται αναφορά για τα συστήματα παρακολούθησης του Ήλιου. Στο Κεφάλαιο 5 παρουσιάζονται διάφορες τεχνολογίες ψύξης που έχουν δημοσιευθεί σε επιστημονικές εργασίες και συνοδεύουν τα συγκεντρωτικά συστήματα, λόγω των υψηλών θερμοκρασιών που επιφέρουν στα κύτταρα. Στο Κεφάλαιο 6 γίνεται αναφορά στο πειραματικό κομμάτι της εργασίας με παρουσίαση των μετρητικών οργάνων και των αποτελεσμάτων των μετρήσεων που έγιναν στο συγκεντρωτικό σύστημα V-Trough, στο σταθερό φωτοβολταϊκό μονοκρυσταλλικού πυριτίου και στο φωτοβολταϊκό πλαίσιο μικρομορφικού πυριτίου (thin film). Στο Κεφάλαιο 7 παρουσιάζονται υπολογιστικές μέθοδοι για την εκτίμηση της ακτινοβολίας και της παραγόμενης ενέργειας από το V-Trough και το σταθερό φωτοβολταϊκό πλαίσιο σε ετήσια βάση. Επίσης παρουσιάζεται μέθοδος υπολογισμού της βέλτιστης κλίσης για κεκλιμένες επιφάνειες και μέθοδος για την αποφυγή σκιάσεων αυτών των επιφανειών. Επίσης γίνεται εξομοίωση φωτοβολταϊκών εγκαταστάσεων με χρήση του προγράμματος PV*SOL. Το Κεφάλαιο 8 περιέχει τα συμπεράσματα ως προς τη χρήση του συγκεντρωτικού συστήματος, τις υπολογιστικές μεθόδους και τα υπόλοιπα θέματα που παρουσιάσθηκαν σε αυτή τη διπλωματική. / The solar energy is practically inexhaustible, and it is the main form of renewable source. The solar radiation provides the Earth with a huge amount of energy. The solar cells, known as photovoltaics, compose an approach of high technology for the direct conversion of light into electricity. During this thesis an analytic description of their operation was made and specifically under low concentration conditions. Particularly, in the 1st Chapter is made an introduction to the renewable sources and specifically in solar. Showing the evolution of R.E.S. in Greece and the reasons that turned humans into new forms of energy than the fossil fuels. Chapter 2 refers to the theory of solar geometry associated with the two main movements of Earth, the daily rotation and the yearly around the Sun. Presented theoretical models, predicting and calculating the solar radiation on surfaces at the Earth’s level. Chapter 3 presents a brief description of the operation of photovoltaic cells and the physical properties of these semiconductor devices. Also refers to the existing photovoltaic technologies with their advantages and disadvantages and to various effects that influence their operation. Chapter 4 is devoted to the concentrating systems and all existing geometries used at this time and especially the V-Trough geometry that used in the experiments. A reference also is made to solar tracking systems. Chapter 5 presents various cooling technologies that have been published in scientific papers and accompanying concentrating systems due to high temperatures that cause to cells. Chapter 6 refers to the experimental part of this thesis with presentation of the experimental devices and the results of measurements made in the concentrating system V-Trough, the stable monocrystilline silicon photovoltaic panel and the micromorph silicon thin film panel. Chapter 7 presents computational methods for the estimation of radiation and the energy produced by the V-Trough and stable photovoltaic panel on an annual basis. Also presents method of calculating the optimum tilt for inclined surfaces and a method of avoiding the shading on this surfaces. Also a simulation of photovoltaic plants is made by the PV*SOL software. Chapter 8 contains the general conclusions related with the experimental results, the theoretical calculations and all the other issues that presented in this thesis.

Passivation of silicon surfaces remains a critical factor in achieving high conversion efficiency in solar cells, particularly in future generations of rear contact cells -the best performing cell geometry to date. In this thesis, passivation is characterised as either intrinsic or extrinsic, depending on the origin of the chemical and field effect passivation components in dielectric layers. Extrinsic passivation, obtained after film deposition or growth, has been shown to improve significantly the passivation quality of dielectric films. Record passivation has been achieved leading to surface recombination velocities below 1.5 cm/s for 1 Ωcm n-type silicon covered with thermal oxide, and 0.15 cm/s in the same material covered with a thermal SiO2/PECVD SiNx double layer. Extrinsic field effect passivation, achieved by means of corona charge and/or ionic species, has been shown to decrease by 3 to 10 times the amount of carrier recombination at a silicon surface. A new parametrisation of interface charge, and electron and hole recombination velocities in a Shockley-Read-Hall extended formalism has been used to model accurately silicon surface recombination without the need to incorporate a term relating to space-charge or surface damage recombination. Such a term is unrealistic in the case of an oxide/silicon interface. A new method to produce extrinsic field effect passivation has been developed in which charge is introduced into dielectric films at high temperature and then permanently quenched in place by cooling to room temperature. This approach was investigated using charge due to one or more of the following species: ions produced by corona discharge, Na⁺, K⁺, Cs⁺, Mg²⁺ and Ca²⁺. It was implemented on both single SiO₂ and double SiO₂/SiN_x dielectric layers which were then measured for periods of up to two years. The decay of the passivation was very slow and time constants of the order of 10,000 days were inferred for two systems: 1) corona-charge-embedded into oxide grown on textured FZ-Si, and 2) potassium ions driven into an oxide on planar FZ-Si. The extrinsic field effect passivation methods developed in this work allow more flexibility in the combined optimisation of the optical properties and the chemical passivation properties of dielectric films on semiconductors. Increases in cell Voc, Jsc and η parameters have been observed in simulations and obtained experimentally when extrinsic field effect passivation is applied to the front surface of silicon solar cells. The extrinsic passivation reported here thus represents a major advancement in controlled and stable passivation of silicon surfaces, and shows great potential as a scalable and cost effective passivation technology for solar cells.

Cu2ZnSnS4 (CZTS) is a thin film solar cell material that only contains abundant elements and for which promising conversion efficiencies of 9.2 % have been shown. In this thesis composition measurements and reactive sputtering of precursors for CZTS films have been studied. These precursors can be annealed to create high quality CZTS films. Accurate control and measurement of composition are important for the synthesis process. The composition of a reference sample was determined using Rutherford backscattering spectroscopy. This sample was thereafter used to find the composition of unknown samples with x-ray fluorescence measurements. Pros and cons with this approach were discussed. The reactive sputtering process, and the resulting thin films, from a CuSn- and a Zn-target sputtered in H2S-atmosphere were investigated and described. A process curve of the system was presented and the influence of sputtering pressure and substrate temperature were examined. The pressures tested had little influence on the film properties but the substrate temperature affected both composition and morphology, giving less Zn, Sn and S and a more oriented film with increasingly facetted surface for higher temperatures. The precursors produced with this method are suggested to have a disordered phase with randomized cations, giving a CZTS-like response from Raman spectroscopy but a ZnS-pattern from x-ray diffraction measurements. The films have an excellent homogeneity and it is possible to achieve stoichiometric sulfur content. The complete steps from precursors, to annealed films, to finished solar cells were investigated for three controlled compositions and three substrate temperatures. The films sputtered at room temperature cracked when annealed and thus gave shunted solar cells. For the samples sputtered at higher temperatures the trend was an increased grain size for higher copper content and increased temperature. However, no connection between this and the electrical properties of the solar cells could be found.

L’objectif de ces travaux de thèse est double : développer des méthodes de caractérisation alternatives des teneurs en dopants dans le silicium compensé, et améliorer la compréhension de l’influence à l’échelle nanométrique de la compensation du dopage sur les mécanismes de transport. Pour cela, les différents mécanismes de conduction électrique à l’œuvre dans le silicium compensé, et plus précisément l’influence des teneurs en dopants sur ceux-ci, ont été étudiés en détail dans la gamme de température [15K-350K] à partir d’un dispositif à effet Hall. Un premier travail a consisté à enrichir les modèles théoriques utilisés pour décrire la variation avec la température de la densité de porteurs libres, et a permis d’optimiser une méthode de caractérisation préexistante basée sur l’ajustement de ces modèles aux données expérimentales mesurées par effet Hall. Un second volet a consisté à étudier la possibilité d’utiliser le phénomène de conduction électrique par « hopping » pour la quantification des teneurs en dopants, via la préparation d’échantillons d’étude à degrés de compensation contrôlés. Fort des résultats obtenus, trois techniques inédites basées sur la mesure de résistivité en température ont ainsi été proposées. Celles-ci ont ensuite été utilisées pour la caractérisation de matériaux issus de procédés industriels (lingot issu du recyclage de cellules photovoltaïques d’une part, et lingot issu de la purification bas coût de Si métallurgique d’autre part). Les résultats ont ensuite été confrontés aux techniques de caractérisation usuelles. Enfin, des simulations (de type Monte-Carlo) de la répartition spatial du potentiel électrique dans le matériau ont permis de préciser l’influence de la compensation sur le désordre électrostatique dans le matériau, et notamment sur la mobilité des porteurs de charge. / This study aims both at developing alternative characterization techniques for the determination of dopant concentrations in compensated silicon, and at improving the understanding of the effect of compensation on transport mechanisms at the nanometer scale. To do so, the different electrical conduction mechanisms occurring in compensated silicon, and more precisely the influence of dopant concentration on the latter, are studied in details in the temperature range [15K-350K] thanks to an Hall effect device. A first step consisted in enriching the theoretical models used to describe the variation of charge carrier density with temperature. It lead to an optimization of an existing characterization technique based on the fitting of those models to the experimental data measured by Hall Effect. A second step consisted in studying the possibility to use hopping conduction mechanisms to quantify dopant densities, via the preparation of model samples with a controlled compensation ratio. The results allowed to construct three innovating techniques based on resistivity measurements with temperature. The latter have then been used to characterize industrial materials (one ingot originating from recycled photovoltaic cells, and one ingot coming from the purification of metallurgical grade silicon). The results have then been compared to usual characterization techniques. Finally, Monte-Carlo type simulations of the spatial distribution of the electrical potential in silicon, allowed to clarify the influence of compensation on the electrostatic disorder in the material, and particularly on the charge carrier mobility.

Cette thèse porte sur la réalisation de composants photoniques à base de fils de nitrures III-V. Les fils de GaN non-catalysés ont été élaborés de manière auto-assemblée par épitaxie en phase vapeur aux organométalliques (MOVPE) sur saphir. Un des axes de ce travail a porté sur la croissance organisée de ces fils à travers un réseau d’ouvertures défini par lithographie et gravure d’une couche de SiNx. Nous avons étudié en particulier l’influence des paramètres de croissance (température, pression, ratio V/III) et du motif sur l’homogénéité de la croissance sélective. Ces fils ont servi de substrat pour la croissance d’hétérostructures radiales cœur-coquille InGaN/GaN.D’autre part, la croissance, la fabrication et les propriétés physiques de trois types de composant ont pu être étudiées :-Des cellules solaires à fils uniques. Nous avons comparé l’efficacité de conversion de deux types d’hétérostructures : des coquilles épaisses d’In0.1Ga0.9N et des coquilles à 15 et 30 puits quantiques In0.18Ga0.82N/GaN. Après optimisation du contact électrique sur la coquille p-GaN, un rendement maximal de 0,33 % a été obtenu avec des fils à 30 puits quantiques sous éclairement équivalent à 1 soleil (AM1.5G). Le seuil d’absorption mesuré par spectroscopie de photocourant varie entre 400 et 440 nm.- Une plateforme émetteur-détecteur. Le système, qui fonctionne à 400 nm, comprend deux fils de GaN à hétérostructure radiale InGaN/GaN positionnés sur le même substrat et couplés par un guide d’onde en SiNx. La caractérisation électrique du dispositif a mis en évidence une durée de commutation inférieure à 0,25 s sans photocourant persistant.- Des diodes électroluminescentes (LED) flexibles. Ces diodes qui émettant dans le visible (400-470 nm) ont été réalisées en se basant sur une approche hybride organique/inorganique. Les fils émetteurs à puits quantiques InGaN/GaN sont encapsulés dans une matrice organique de PDMS puis détachés de leur substrat de croissance. Les contacts sont réalisés à partir de nanofils d’argent qui présentent l’avantage d’être à la fois flexibles, transparents et conducteurs. A partir de ce procédé, une LED bicolore flexible a été réalisée en combinant des émetteurs bleus et « verts ». / This thesis reports on the realization of photonic devices based on nitride wires. Self-assembled GaN wires were grown without catalyst by metal-organic vapor phase epitaxy (MOCVD) on sapphire substrates. Part of this work focused on the selective area growth of GaN wires through a dielectric SiNx mask with regular arrays of holes defined by lithography and dry etching. We studied the influence of the growth conditions (temperature, pressure, V/III ratio) and pattern geometry on the homogeneity of the selective area growth. These wires were used as templates for the growth of core-shell InGaN/GaN heterostructures. In addition, the growth, microfabrication process and properties of three types of devices were studied:- Single wire solar cells. We compared the efficiency of two type of heterostructures: shells composed of thick In0.1Ga0.9N layers and In0.18Ga0.82N/GaN quantum wells. After optimization of the electrical contact on the p-GaN shell, a maximal conversion efficiency of 0,33 % was obtained on single GaN wires with a shell of 30 quantum wells under 1 sun illumination (AM1.5G). Photocurrent spectroscopy revealed that the wire absorption edge varied between 400 and 440 nm.- An integrated photonic platform. The system, that operates around 400 nm, is composed of two GaN wires with radial InGaN/GaN heterostructures positioned on the same substrate and coupled with a SiNx waveguide. The electrical characterization of the platform revealed a switching speed inferior to 0.25 s without persistent photocurrent.- Flexible light emitting diodes (LED). The LED fabrication is based on a dual approach which associates inorganic InGaN/GaN emitters (400-470 nm) and a polymer. The wires are encapsulated in a PDMS matrix before being detached from their native substrate. Electrical contacts are made with silver nanowires which are flexible, highly conductive and transparent in the visible range. Based on this procedure a two-color LED was realized by stacking a blue and a “green” LED.

Magister Scientiae - MSc (Chemistry) / The increasing cost of fossil fuel energy production and its implication in environmental pollution and climate change created high demand for alternative and renewable sources of energy. This has led to great interest in research in the field of photovoltaic or solar cells Due to the abundance of sunlight, the technology is sustainable, non-polluting and can be implemented at places where power demand is needed, for example in rural areas. Solar cell devices that have been commercialized are currently based on silicon technology, involving the use of monocrystalline, polycrystalline and amorphous silicon. Although they produce highly efficient solar cells, the cost of Si solar cells is too high. Second generation solar cell materials such as cadmium telluride and third generation materials such as perovskites and organic polymers have been receiving much attention recently. However, they lack the efficiency of Si solar cells. This research proposes the development of high energy conservation photovoltaic cells from novel low-cost organosilicon polymers. The aim was to develop novel highly branched organosilane polymers such as poly(3-hexythiophene), polydi(thien-2-yl)dimethylsilane, poly(3-hexyl- [2,2'] bithiophenyl-5-yl)-dimethyl-thiophen-2yl-silane) as electron donors along with zinc oxide nanorod as the electron acceptor which were able to bring the efficiency of the resultant photovoltaic cell close to that of current Si solar cell. / 2021-08-31

Magister Scientiae - MSc / Solar energy generation arises as a result of direct conversion of sunlight into electricity a by solar cell; which is mainly made up of a semiconducting material incorporated into a system. It is emerging as one of the most reliable and cost efficient renewable energy sources. Within the solar field, organic bulk heterojunction photovoltaic cells have proved of being able to have a great impact in the future years; mainly due to the easy processability of the active layer and substrate, their cost effectiveness and above all, a good power conversion efficiency associated to the close 3-dimensional interpenetrating network that is generated from blending donor and acceptor semiconducting materials together in a bulk heterojunction active layer. In this research work, we therefore report on the study of a newly developed organic bulk heterojunction active layer based on a blend of a star-copolymer generation 1 poly(propylenethiophenoimine)-co-poly(ethylenedioxythiophene) (G1PPT-co-PEDOT) as donor material with N,N-diisopropylnaphthalene diimide (NDI) as acceptor material. Both materials were chemically synthesized. The synthesis of G1PPT-co-PEDOT started first by the functionalization of generation 1 poly(propyleneimine) tetramine, G1PPI into G1PPT by condensation reaction in the presence of 2-thiophene carboxaldehyde under Nitrogen gas followed by the copolymerization of G1PPT with ethylene dioxythiophene (EDOT) monomer in the presence of ammonium persulfate, (NH4)2S2O8 as oxidant. On the other hand, NDI was also synthesized via condensation reaction of 1,4,5,8-naphthalene tetracarboxylic dianhydride in the presence of two (2) equivalences of N,N-diisopropylamine at 110 oC overnight in DMF. Both materials were characterized using FT-IR, UV-Vis spectroscopy, Fluorescence spectroscopy, Voltammetry, HRSEM microscopy and XRD. Based on the cyclic voltammetry and UV-Vis results, we were able to calculate the HOMO, LUMO and band gap energy (Eg) values of both the donor and acceptor to be -4.03 eV, -6.287 eV and 2.25 eV for iii the donor G1PPT-co-PEDOT respectively and -4.302 eV, -7.572 eV and 3.27 eV for the acceptor respectively. From these results, the energy diagram for both donor and acceptor was drawn and it comes out that the separation between the HOMO of the donor and the LUMO of the acceptor ΔEg = 1.985 eV, the ideal value for a good donor-acceptor combination. Also the offset energy that is, the energy difference between the LUMO of the donor and the LUMO of the acceptor is 0.302 eV.

The municipality of Borlange is planning to build a new modern, social and an ecologically sustainable district due to an increase in the city’s population. Over 1200 homes shall be built for people from all sections of the society. Due to such high levels of migration into the city, it is of utmost importance for the society to ensure that all the new constructions would be energy efficient and focused towards the goal of creating a sustainable society. The main objective of this study is to understand the importance of planning for Photovoltaics (PV) in new areas and performing a series of simulations for different scenarios with varying degrees of PV penetration for the planned residential area of Jakobsgardarna in Borlänge, Sweden.   This was achieved by determining the load profiles for all buildings by thorough investigation over the previous works in the analysis of household demand loads and calculating the available roof area in several orientations with the help of model maps drawn to scale. Due to varied types of roofs and their structures, it was assumed that all buildings have a similar roof structure i.e. tilted roofs having a tilt of 30°. Batch simulation was performed in PVSyst for a base case scenario which provides the reference point for determining the total PV power and the total PV output in all orientations.   The PV penetration is measured in terms of energy by dividing the total PV output with the annual demand load. Various scenarios of PV penetration are created based on the available roof areas at particular roof orientations. It can be observed that the level of PV penetration is highly dependent on the orientation of roofs. A 17% of PV penetration is observed when PV is installed only on South-facing roofs while the PV penetration reduces drastically to 9% when PV is installed only on East-West facing roofs even though there isn’t a linear reduction in the available roof area.

Les matériaux les plus répandus dans le domaine du photovoltaïque (PV) organique à base de polymères sont le poly(3-hexylthiophène) régiorégulier (rr-P3HT) et le [6,6]-phenyl-C61-butyric acide methyl ester (PCBM). La couche active est une hétérojonction en volume (BHJ) de nanodomaines interpénétrés accepteur d’électron (le PCBM) et donneur d’électron (le P3HT). Le contrôle de la morphologie de la couche active et de sa stabilité est un défi majeur pour le développement des cellules organiques et est au centre de ce travail de thèse.Dans un premier temps, nous avons cherché à contrôler la morphologie du mélange P3HT:PCBM via l’utilisation de compatibilisants. Deux familles de copolymères à blocs rigide et souple ont été étudiées. Elles ont en commun leur bloc rigide à base de P3HT et diffèrent par leur bloc souple. Pourla première famille, le bloc souple poly-butylacrylate est greffé de C60, ce qui lui confère une affinité chimique avec les domaines de PCBM, et la seconde famille a un bloc souple poly(4-vinylpiridine) (P4VP) non greffé en C60. De par son affinité chimique avec le C60, le PCBM se localisera préférentiellement au voisinage des domaines P4VP.Dans un deuxième temps, nous avons exploité les propriétés d’auto-assemblages des copolymères à blocs afin de les étudier en tant que matériaux photo-actifs. Nous avons cherché à appréhender l’influence de la nature du bloc flexible let de a taille des blocs souple et rigide sur l’organisation des copolymères ainsi que sur les propriétés de transport de charge et sur les performances PV. / Polymer/fullerene bulk heterojunction (BHJ) solar cells use an interpenetrating network of TT-conjugated electron-donor polymers and electron-acceptor C60 as photo-active layer. Currently, the most investigated blends are constituted of regioregular poly(3-hexylthiophene) (rr-P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The nanostructured active layer determines to great extend the overall performance of the devices.First of all, we introduced rod-coil block copolymers as compatibilizer into P3HT:PCBM blends and investigate their influence on the blend morphology and the related photovoltaic performance. Two P3HT-based block copolymer families have been studied. The first one has a C60-grafted polybutylacrylate coil block and the second one is based on poly(4-vinylpyridine) (P4VP) coil block. The film morphology and device efficiencies are investigated as a function of copolymer content, P3HT/PCBM mass ratio and coil nature.A second possible route to obtain a stable donor/acceptor nanostructure consists of using semiconductor block copolymers as photoactive layer, since these materials are able to self-assemble into donor/acceptor BHJ by microphase separation. We explored P3HT-P4VP rod-coil block copolymers blended with PCBM in view of their utilization in photovoltaic devices. The copolymer selfassembles into nano-domains rich in either P3HT or P4VP, while the strong chemical affinity of P4VP with PCBM leads to an accumulation of the latter in the P4VP domains, providing them an acceptorcharacter. It is found that organized and thermally stable thin films, that exhibit ambipolar field effect mobilities, can be achieved for a specific rod/coil ratio.